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Transforming Agriculture to Mitigate Climate Change and Support Public Health

Many of us spent most of 2020 sheltering at home, doing our part to curb the pandemic we are weathering as a global community. While there is solidarity in the fact that people around the world are modifying their lives to flatten the curve—wearing masks, socially distancing, and working remotely when possible—many of us are eagerly awaiting the vaccine that allows us to emerge from our shelters and breathe a sigh of relief.

But, is a vaccine the ultimate solution to our public health crisis? While there is no denying we need to address the immediate threat of covid-19, this pandemic is itself a symptom of a challenge that will not be solved by modern medicine. That challenge is climate change, fueled by the loss of natural habitats and biodiversity. If we ignore this broader issue, we face a world where we will likely be challenged by one pandemic after another.

Humans are disrupting natural systems and this is a primary factor in the spread of infectious diseases. As our planet warms and more natural habitats are lost, many species are expanding out of their natural ranges and moving towards the poles¹. As a result, they come into contact with species they would not normally be interacting with, which creates opportunities for pathogens to infect novel hosts, including humans. We have seen these dynamics play out with Ebola, Zika, Hantavirus, and other diseases around the globe²,³. To reduce the risk of infectious disease spread, we need to address the major sources of greenhouse gas emissions and the human activities that threaten natural habitats and biodiversity.

Modern-day agriculture is a major contributor to climate change. The International Panel on Climate Change estimates that direct agricultural greenhouse gas emissions account for over 10% of total anthropogenic (human caused) greenhouse gas emissions⁴.

Agricultural systems that rely on synthetic inputs to compensate for low biodiversity contribute substantially to the emission of three key greenhouse gases: carbon dioxide, nitrous oxide and methane. Field operations and the production of synthetic fertilizers and other inputs are largely responsible for agricultural carbon dioxide emissions, and the use of synthetic fertilizers and livestock production are the main sources of agricultural nitrous oxide and methane emissions, respectively⁴,⁵,⁶.

In the U.S., most livestock are raised in large confinement facilities, rather than on pasture where they have the potential to help build healthy soils that store, or sequester, carbon. Moreover, confined animal operations negatively impact air and water quality, and create prime conditions for infectious disease spread that could spill over to humans⁷.

Agriculture is also the main driver of deforestation, the largest cause of habitat loss worldwide⁸. In particular, large-scale beef production causes massive deforestation, particularly in the tropics⁹. Forests, especially tropical forests, store large amounts of carbon in the soil and in their biomass. When a forest is destroyed, the potential for carbon storage is lost, and if the forest is removed through burning, carbon stored in the vegetation is released to the atmosphere, accelerating global warming. Land-use changes associated with the expansion of large-scale, industrial agricultural systems erode valuable biodiversity and result in simplified landscapes that are more susceptible to outbreaks of agricultural pests and diseases. To compensate, these simplified systems become increasingly reliant on synthetic inputs.

When a forest is destroyed, the potential for carbon storage is lost, and if the forest is removed through burning, carbon stored in the vegetation is released to the atmosphere, accelerating global warming.

Being Part of the Solution

While agriculture is fueling climate change and habitat loss, it can be transformed to become part of the solution. By adopting a systems-based, ecological approach to producing food, agriculture can help reduce negative climate impacts, conserve biodiversity and support human health. Organic agriculture provides this ecological framework for food production and is grounded in measurable standards for biodiversity and soil health, which are the foundations of a healthy farming system, and ultimately a healthy society.

By focusing on soil health building practices, organic agriculture has the potential to play a large role in mitigating climate change by reducing greenhouse gas emissions and sequestering carbon. Organic producers are prohibited from using synthetic fertilizers, the largest source of agricultural nitrous oxide emissions. By building healthy soils that host a diversity of beneficial organisms and support vigorous crop growth, organic producers enhance their system’s resilience to a changing climate. Healthy soils not only increase crop resilience to stressful conditions, they also play a critical role in regulating the global climate by converting organic residues into stable organic matter and storing atmospheric carbon dioxide in the soil¹⁰.

To protect these vital services, the USDA National Organic Program (NOP) Standards mandate the use of best conservation management practices such as diversified crop rotations, intercropping and cover cropping to build soil organic carbon and protect soil health. Diversified crop rotations and intercrops add diversity to farming systems across space and time, which help break pest and disease cycles and increases the abundance and diversity of beneficial soil organisms¹¹. Planting cover crop mixtures with deep root systems can reduce soil erosion and break up compacted soil, store carbon deep into the soil profile and increase the water holding capacity of soils, making the system more resilient to extreme weather events such as heavy rains or floods¹².

While each of these diversification practices individually helps pull carbon out of the atmosphere and builds resilience, the true potential for climate change mitigation and adaptation comes from combining these practices through diversification strategies such as conservation agriculture, agroforestry and integrated crop-livestock systems. For example, reintegrating crops and livestock using advanced grazing management has the potential to sequester enough soil organic carbon to offset the associated enteric methane and manure greenhouse gas emissions¹³. There is also evidence that by improving forage quality, these systems can reduce methane emissions from livestock by almost a third. Managed rotational grazing systems also enhance nutrient cycling and reduce the need to import nutrients in the form of fertilizers or livestock feed.

By building biodiversity into the farming system, best organic management practices also have the potential to support more abundant and diverse communities of animals compared to simplified, input-intensive farming systems. Implementing diversification practices such as wildflower strips, hedgerows and diversified crop rotations can enhance the abundance of wild insect species that support pollination, pest control, nutrient cycling and other important ecosystem services¹⁴. Organic systems that incorporate high agrobiodiversity can also support wildlife-friendly approaches to farming where the goal is to integrate wildlife conservation with production. By planting and preserving habitat for wildlife, such as hedgerows or riparian forest buffers, organic farms can serve as wildlife corridors that connect parcels of natural habitat and provide refuge from synthetic chemical inputs that may be present in the broader landscape.

 

The Path Forward

To protect public health, we need to adopt and promote sustainable food production practices that safeguard our natural systems and conserve biodiversity. Organic agriculture has great potential to sequester carbon, mitigate greenhouse gas emissions, and build resilience to a changing climate and protect biodiversity. To realize this potential, the public sector must significantly and rapidly increase its investment in organic research, extension and education, and prioritize research topics that help producers address the climate crisis by reducing net greenhouse gas emissions and adapting their operations to shifting weather patterns.

Some current policy proposals, for example, seek to pay farmers for sequestering carbon in their soils; however, to expand these programs, we need additional research on how much carbon is retained in organically managed soils and for how long. We also need to develop more accurate tools to fully understand organic agriculture’s climate mitigation potential. For example, different tools to measure soil carbon sequestration can yield different results on the same field. Furthermore, soil carbon is extremely variable across different soil types, depths, climate conditions and time periods. Even in apparently uniform fields, soil carbon content can vary by as much as five-fold¹⁵. This is one aspect of climate mitigation within agriculture that needs more research so we can better evaluate the climate benefits of various agricultural practices.

Additionally, both USDA and Congress can do more to promote the transition to organic production systems and improve access for organic producers to federal conservation programs. Many of these programs pay farmers and ranchers for implementing advanced grazing management systems, resource-conserving crop rotations and cover crops as well as for protecting wildlife habitat. These programs and the practices they support represent tried and true solutions that not only have climate benefits, but also protect our natural resources, improve air and water quality, and support biodiversity.

Organic and conservation agriculture with their manifold environmental benefits can help farmers and ranchers build resilience into their operations, actively contribute to climate change mitigation and transform our food production system to one that benefits our health and the health of our planet. We cannot afford to stall action on climate change any longer. If we are to limit the likelihood of future pandemics and other catastrophic events driven by a changing climate, we must prioritize and support systems-based, ecological solutions that protect our food systems, the environment and public health.

Cover cropping builds soil organic carbon and protects soil health, and can also provide a food source for pollinators.

 

Sources

  1. Pecl, G. T., et al. 2017. Biodiversity redistribution under climate change: Impacts on ecosystems and human well-being. Science. 355.
  2. Frumkin, H., J. Hess, G. Luber, J. Malilay, M. McGeehin. 2008. Climate change: the public health response. Am J Public Health. 98:435–445.
  3. Yang, Y. T., M. Sarfaty. 2016. Zika virus: A call to action for physicians in the era of climate change. Preventive Medicine Reports. 4: 444-446.
  4. Intergovernmental Panel on Climate Change (IPCC). 2014. Climate Change 2014: Mitigation of Climate Change, Working Group III Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.
  5. Burger, M., L. E. Jackson, E. J., Lundquist, D. T., Louie, R. L., Miller, D. E., Rolston, K. Scow. 2005. Microbial responses and nitrous oxide emissions during wetting and drying of organically and conventionally managed soil under tomatoes. Biol Fertil Soils. 42:109-18.
  6. Charles, A., P. Rochette, J. K. Whalen, D. A. Angers, M. H. Chantigny, N. Bertrand. 2017. Global nitrous oxide emission factors from agricultural soils after addition of organic amendments: A meta-analysis. Agric Ecosyst Environ. 236: 88-98.
  7. Hribar, C., and Schultz, M. 2010. Understanding concentrated animal feeding operations and their impact on communities. National Association of Local Boards of Health: Bowling Green, Ohio.
  8. Hosonuma, N., et al. 2012. An assessment of deforestation and forest degradation drivers in developing countries. Environ. Res. Lett. 7.
  9. Union of Concerned Scientists. 2016. Cattle, Cleared Forests, and Climate Change: Scoring America’s Top Brands on Their Deforestation-Free Beef Commitments and Practices. www.jstor.org/stable/resrep17253.
  10. Moebius-Clune, B.N., D. J. Moebius-Clune, B. K. Gugino, O. J. Idowu, R. R. Schindelbeck, A. J. Ristow, H. M. van Es, J. E. Thies, H. A. Shayler, M. B. McBride, D.W. Wolfe, G.S. Abawi. 2016. Comprehensive Assessment of Soil Health: The Cornell Framework. Edition 3.1. Cornell University, Geneva, NY. 123 pp.
  11. Lin, B. B. 2011. Resilience in agriculture through crop diversification: Adaptive management for environmental change. Bioscience. 61:183-193.
  12. Marshall, M.W., P. Williams, A. Mirzakhani Nafchi, J. M. Maja, J. Payero, J. Mueller, and A. Khalilian. 2016. Influence of Tillage and Deep Rooted Cool Season Cover Crops on Soil Properties, Pests, and Yield Responses in Cotton. Open Journal of Soil Science. 6: 149-158.
  13. Manale, A., S. Hyberg, N. Key, S. Mooney, T. L. Napier, M. Ribaudo. 2016. Climate change and U.S. agriculture: opportunities for conservation to reduce and mitigate emissions and to support adaptation to rapid change. J. Soil & Water Conserv. 71: 69-81.
  14. Kremen, C., and A. M. Merenlender. 2018. Landscapes that work for biodiversity and people. Science. 362.
  15. Keith Paustian et al. “Quantifying carbon for agricultural soil management: from the current status toward a global soil information system,” Carbon Management 10 (2019). 10.1080/17583004.2019.1633231 (accessed January 22, 2020).

The Organic Farming Research Foundation (OFRF) is a non-profit foundation that works to foster the improvement and widespread adoption of organic farming systems. OFRF cultivates organic research, education and federal policies that bring more farmers and acreage into organic production.

Fundamentals of Hemp Nutrition

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Fertilizer needs for hemp plants are similar to the needs of larger vegetable plants, such as tomatoes. As with other annuals, hemp plants require different nutritional needs during their various growth stages.

 

Nitrogen, Phosphorous and Potassium

In the beginning stage of the life cycle, hemp plants need a dominant nitrogen source. The plants also need a good starter fertilizer rich in phosphorous and potassium, according to James Knox, owner of KLR Farms. KLR is a multi-state business that grows, breeds and produces feminized hemp seeds and plants.

There are designer brands that Knox likes and uses. Mills Nutrients is one.

“Mills offers a mineral based and an organic for certified organic growers,” Knox said. There is a bio-mineral line for various stages of a plant’s life. Their products are designed and bottled in Holland, but they have retailers sprinkled throughout the northwest, including many in California.

BioAg is another brand that Knox uses. Located in Independence, Ore., BioAg specializes in fulvic acid. Knox especially likes Ful-Power®, a product which can be used as a foliar spray. It can also be used on clones and cuttings as a bare-root dip and to activate seeds. Ful-Power® is listed by the Organic Materials Review Institute (OMRI).

West Coast Horticulture is another fertilizer company that Knox uses and trusts. They supply liquid and dry organic fertilizers. The liquids are compatible with injector systems and drip irrigation and are processed from fermented plant materials and minerals. The liquid fertilizers contain bio-available forms of nitrogen, phosphorous and potassium. They also supply humic acid, microbial and bio-active compounds. West Coast’s products are compliant with the National Organic Program (NOP) and are registered as an Organic Input Material (OIM) with California Department of Food and Agriculture (CDFA) and listed with WSDA, ODA and OMRI.

 

Kelp Extract and Enzymes

Knox uses what he calls “high-value” kelp extracts. Nirtozime™ is a brand he mentions by name. It’s an organic biostimulant with growth hormones and micronutrients.

As far as enzymes go, Knox favors one called Enzymes Komplete™. It’s not a fertilizer, but rather an enzymatic cleanser to clean and recondition the growing medium. It can also be used as a cleansing agent for tools and processing machines to prevent disease and encourage healing. The product comes from a company out of Canada.

 

Fish Fertilizer

Non-hydrolyzed processed fish has the oils removed for use in cosmetics and the proteins removed for animal feed, Knox said. “It’s fish emulsion. It’s garbage. Literally, you’re left with the garbage.”

Use a high-quality fish fertilizer, Knox urged.

“Make sure it’s cold-processed, hydrolyzed whole fish broken down by enzyme digestion.” This process keeps all of the bio-active ingredients intact. It also supplies complex carbohydrates for the microorganisms, he said.

“All the amino acids are still intact. They are growth promoters – the overall general health additive. They are the building blocks of life.”

 

Silica

Silicon (silica)is an abundant mineral in many soils, but only the monosililic acid form is available to plants. High-quality silica can be used as a foliar feed or as an on-ground fertilizer, Knox said. For field growing, one of Knox’s favorite brands is Vitalize™ from Mills Nutrients. It’s a high-silicate nutrient that can be used throughout the life of the plant.

Silica helps toughen plants, which assists with disease and pest resistance.

“Silica helps regulate plant growth. It doesn’t allow plants to overgrow themselves, so they don’t get leggy and weak. The plant tissue itself is often literally harder for the pests to eat and chew,” Knox said. “Pests are a vector for disease.”

Anywhere a pest pierces or chews a plant is a weakened spot for disease to enter. Also, the feces that insects leave behind can encourage mold and mildew problems.

“Smart growers just simply cull those plants,” Knox said about any runts or seriously pest-infested plants.

Ari Gamboa uses Clonex Rooting Gel™ to root cuttings (photo courtesy A. Gamboa.)

Compost Tea

Knox has his own compost tea brewer. He uses an application of tea every one to two weeks for both indoor and outdoor growths.

“You want to use bacterial-dominant, not fungal-dominant,” Knox said about the compost tea recipe he uses. “Bacterial-dominant is aggressive and works quickly for annual crops such as hemp. It breaks down the organic and non-organic matter by eating it and pooping it out.”

Fungal-dominant teas take longer to work, which isn’t as beneficial to an annual crop.

 

Endomycorrhizae

Endomycorrhizae can be used in seedling mixes or to water in newly transplanted seedlings or cuttings.

Knox likes VAM®, another BioAg product. It has seven species of granular arbuscular mycorrhizal fungi, which aids in plant and root growth. It can be used in a variety of ways, including as a dry broadcast in outdoor grows, or added to water or other liquid for hydroponic, irrigation and hand-watering applications. Use it for seed treatments, cuttings and reinforcement after using compost tea.

“It’s the industry’s best mycorrhizal,” Knox said.

Knox, who grows under cover in Illinois, and outdoors and under cover in Oregon, uses all of the above fertilizers and amendments on his indoor crops.

 

Chicken Manure

“Designer brands aren’t always applicable to large scale growers,” Knox acknowledged.

For plants grown outdoors on a larger scale, Knox suggests PotentGrow™. The company is headquartered out of Tangent, Ore. The product that Knox uses is a 5-2-2 chicken manure pellet.

“It’s my favorite for outdoor production,” he said. “It’s a pellet that is broadcast in the field. Besides the boost in nitrogen, it has organic matter and offers beneficial biology to soils. The microbial fungal blooms overnight.”

 

Boosts

Knox uses more phosphorous during heavy growth periods and during transition – when days grow shorter and trigger plants to flower. “When plants are responding to light change,” Knox said. “Indoors, we trigger that with our lights, of course.”

He gives his plants a boost of extra potassium at the end of their life cycle, right before harvest, when the plants are bulking and ripening.

Use a dominant nitrogen fertilizer at the beginning of a hemp plant’s life cycle (photo courtesy A. Gamboa.)

 

Other Insights

Ari Gamboa, of ERB Company (erbholdings.com) and partnering with KLR Farms (klrfarms.com), is in his third year of growing hemp.

“I’ve been helping James (Knox) grow hemp seed the last three years,” Gamboa said.

Prior to that, Gamboa spent six years growing marijuana for the regulated medical cannabis market. He’s grown cannabis and/or hemp crops in Colorado, Oregon and Wisconsin. Gamboa harvested 30,000 hemp plants in Wisconsin this past fall. “We crushed it!” he said about the harvest.

When starting plants from cuttings, Gamboa prefers Clonex Rooting Gel™. Along with rooting hormones, Clonex Rooting Gel™ also has minerals and trace elements to feed new roots.

When transplanting hemp plants, Gamboa first dusts the planting hole with Azos™, a nitrogen-fixing bacterium, to promote vegetative growth and a healthy root system.

As far as fertilizer during the growing season, “You just have to get a trusted nutrient,” Gamboa said. “As plants start flowering, drop the nitrogen and start raising the P and K.”

At the end of the flowering cycle, and two weeks before harvest, Gamboa flushes the hemp roots with plain water. “It will shock them a little and add some color to the plants,” he said.

Organic Almonds: Why and How From A Grower’s Perspective

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Organically grown almonds and organic nut products have become increasingly popular in the last decade and are a growing market segment, according to Josette Lewis, Almond Board of California’s Chief Scientific Officer. Still, just under 1% of almond acreage in California is organic.

Many growers are exploring the idea of growing organic, but management details and financial incentives aren’t always available. In a presentation during The Almond Conference 2020 presented by Almond Board of California, participating growers and experts spoke about the “fine print” when it comes to organic almonds.

The participants included Geordy Wise, senior vice president of farming operations for Pacific Ag Management; Wes Sperry, CEO of Sperry Farms; and Amelie Gaudin with the Department of Plant Sciences, UC Davis.

 

Organic Management

Most growers would agree that managing organic almonds is a different world compared to conventional almonds. There are many things to consider in order to maximize yields and ultimately capture the premium associated with organic products.

Insect Pests
Many organic growers end up dealing with a lot of the same insects that they already deal with in conventional almonds.

“In Kern County, we have similar pest categories to conventional almonds,” Wise said. “Concerning mite control, the key is to be on the early side and be upfront about it. We’re very mindful of our roads and dust, so we use road oil and sulfates to keep dust down which has been big for mite control. For NOW, I think sanitization still works best for us.”

“Pest management has been one of the larger concerns on our organic farm,” Sperry said. “[In year one,] we used organic fungal and bloom sprays that seemed to work well. On the NOW side, we used mating disruption products that showed results that were on par with or below our conventional nut damage. I was really impressed with some of the products that are out there.”

Weeds
Weed issues in organic almond management, and all organic management, are one of the most difficult management challenges. Organic herbicides are not abundant and costs for them are still high; thus, growers have found other alternatives for their orchards while organic herbicide research continues.

“Regarding weed management, it’s been one of the most challenging aspects of the organic journey so far,” Sperry said. “We made an investment into a propane burner to burn down the weeds in strips. Burning [drip] hoses is a concern with this and it has happened before. We’ve also gone with a wider mower to help clean up more weeds in those rows.”

Wise also uses unique methods for organic weed management. “We’ve used netting underneath the tree row that suppresses and keeps weeds down,” he said. “Weeds still grow out around the edges as well. The downside is the repairs; it’s very maintenance-driven. We also use propane burners. It probably takes a good year to tear up everything and burn it, but you can’t get behind on it. Every 10 to 14 days seems to be working well for us for burning weeds.”

Different growers have different ways of dealing with weed pressures depending on orchard characteristics and weather patterns, but Gaudin believes that cover crops can provide weed suppression during the winter by competing with native vegetation.

“We recognize that there are benefits and tradeoffs as to what might work for different operations,” she said.

Sperry explained the benefits and tradeoffs that his operation has experienced with cover crops. “The success with cover cropping for us really came down to timing,” he said. “We rely on those winter rains to help the cover crops. Since this year has shown little rain, it’s hampered our cover crops. Keeping whatever native vegetation is already there as well is beneficial for the soil. Don’t burn or mow it.”

Wise felt differently about cover crop usage. “I just struggle with the cost of planting cover crops knowing that we’re not getting the rain right now,” he said. “We believe in native cover. The root systems of the weeds can even help with water penetration sometimes.”

Soil Fertility
Feeding the crop with a soil fertility program is another challenge. Sperry and Wise both expressed difficulties implementing a fertility program in their organic operations.

“These nitrogen-based organic fertilizers are really expensive,” Sperry said. “The nitrogen has been the biggest hurdle for us in a budget aspect. You get used to cheap fertilizers coming from conventional, but compared to organic there’s a big difference. You’ve got to be realistic and have a different mindset if you’re coming from conventional to organic. It’s been a learning curve.”

Wise agreed nitrogen fertility is a particular challenge.

“We started with composting using chicken manures for soil fertility, but it created some issues, so I’ll probably stay away from that in the future,” Wise said. “Many of the products we have found to work have shown some other smaller issues such as plugging lines. Nitrogen will be the limiting factor; it’s just part of the game with organics, and you’ve got to be willing to make the commitment.”

Weed control using a propane burner at Sperry Farms.

 

Making the Jump

Starting a new organic almond orchard, especially if transitioning from conventional, can be daunting. There are many available tools and methods that growers can utilize to get started, but, according to Gaudin, it’s going to take some experimenting for the grower as well.

“The research with whole orchard recycling and cover cropping are great ways for a grower to prepare an orchard for planting organic, but there is more to it than individual practices,” she said. “Experimenting with your own operation is going to be critical.”

Sperry and Wise shared their own experiences with starting their organic orchards.

“We found that taking a conventional block and isolating and transitioning it to organic was a good way to start,” Sperry said. “You also have to find a certifier to work with and document all the products and practices that you want to use. There’s a fair amount of paperwork and communication with your certifier to be had.

“It’s a long-term commitment, you likely won’t see profits for two to three harvests,” he continued. “I’m optimistic that when we get past this point, we’ll start to see those premiums.”

“You have to be realistic about everything,” Wise emphasized. “Your costs will increase and yields will probably be reduced, but the market for them [organic almonds] is definitely there.”

Micronutrients: Effective Measurement and Use of Manganese

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There is a great deal of confusion when it comes to correctly understanding the micronutrient manganese and what soil tests can reveal about it. So, perhaps the first question to be asked in this regard should be, “Does a soil test for manganese really reflect the amount of manganese that is actually there in an available form in each particular soil?” And how can you tell if the readout on a soil test is an actual indication of true manganese availability?

To arrive at such an answer, first consider that a multitude of experts maintain that an accurate soil test for manganese does not matter. One line of reasoning used is because there is so much already contained in every soil. The reasoning is that an average acre of soil six and a half inches deep weighs about two million pounds. And of that 2 million pounds of weight per acre, manganese makes up from 100 to 10,000 pounds of that total weight per acre.

Even more, depending upon which source is quoted, 150 bushels of corn requires .08 pounds of manganese, or about 1.25 ounces of manganese per acre. Since about any soil has 100 pounds of total manganese and most far more than that, why worry about ever needing to add manganese to any soil?

Even though this is not the full story, too often it has been used as a good excuse. This is especially true for those who lack any reliable way to measure and convey the available manganese each soil contains. In other words, is the manganese that is there in a form that is useable by the crop?

In order to grow the most nutritious foods, farmers and growers need to know if the actual amount of manganese contained in the soil is adequate to do so. And that measurement should be in the nutrient-available form that plants can take up and utilize.

But as with many natural activities that take place in the soil, the increase happens at a slower pace than plant growth does, and, thus, it is not able to be measured in a relatively short period of time. In fact, it requires about a year from the time of application before the actual increase can be accurately seen on a soil analysis that correctly measures manganese availability.

There is a way to determine whether a soil test is actually measuring nutrient-available manganese in each particular soil. For soils that have good aeration capabilities for optimizing biological activity, a soil test for plant-available manganese should reflect an approximate pound for pound increase in the measured level when any proper form is applied to the soil.

 

Evaluating Soil Tests

Here is a good way to evaluate how accurate a soil test is in reporting actual useable soil manganese. If it has been at least 12 months since the manganese was applied, on soils that have an adequate amount of aeration, the manganese on the test should show an approximate pound for pound increase.

In other words, if 50 pounds of a good plant-available pure manganese sulfate has been applied, the soil should show an available manganese increase of 14 pounds per acre or 7 ppm (since on soils weighing approximately 2 million pounds per acre, the number of pounds applied divided by two equals parts per million.)

The aerobic zone is the top few inches of soil that tends to have enough air to maximize biological activity. This allows all types of soil organisms that need that aeration to digest and convert nutrients that are present there into the most available forms the plants can take up and utilize.

How much aeration is required for adequate biological activity to provide needed soil-available manganese? There are some simple ways to provide a good answer on each property. Realize that the answer will be different from one type of soil to another, and also note that biological activity is closely tied to the soil properties that provide a sufficient amount of air in different soils.

There are at least two possible considerations for immediately measuring potential biological activity on your own property that could be used here to “study nature” instead of a book or article or comments on the internet.

The first method may not be as convenient to accomplish as the second, but it is a sure way to determine the depth of aeration in any given soil. To determine the amount of air and the depth it can penetrate downward in the soil (called the aerobic zone,) find and pull an old wooden fence post.

The depth to which that post has rotted from the top down into the soil is the depth to which air can adequately penetrate there. This will determine the maximum depth to which any particular soil can provide sufficient air for maximizing microbial activity.

Keep in mind that all plants will feed by choice from the aerobic zone, as deep as a fencepost will rot in that soil, when the opportunity to do so is sufficiently provided.

Another way to check for adequate soil aeration right on the farm requires the use of a soil probe that has one side cut away for observation purposes.

To correctly accomplish this test, it is first necessary to find a place where the soil has not been compacted in some way. In other words, find a soil that would only have normal or natural settlement, something without wheel traffic or pugging of the soil by heavy livestock traffic under wet conditions, etc.

Push the probe down deep enough so that at least six or seven inches of soil is visible in the probe. Lay the probe flat on the ground. Now, take your thumb and, beginning at the top, press gently and directly down on the column of soil. Notice how soft or how hard to the touch it feels.

In most soils that are not worked wet or somehow compacted, the first half inch of soil can easily be pressed down. It is soft to the touch. But after that, many soils provide sharp resistance to the pressure from your thumb. Such soils are lacking the proper aeration needed to optimize biological activity in that soil. And it is not until you can press your thumb against the soil without feeling resistance to a depth of four to five inches that the soil tends to have sufficient aeration throughout the aerobic zone (which will generally measure at least 6 to less than 8 inches deep.)

Once you have this type of soil, which contains the ideal characteristics for proper physical structure, then you have a soil that is well suited for correctly testing for available soil manganese. This is not to say that only soils with proper aeration should be treated for a manganese deficiency. But it does mean that soils may not appear to be building up levels from manganese applications under those circumstances.

Stainless steel soil probes, like the one seen here, can be used to extract soil from the ground to check for aeration and moisture content. (photo courtesy Kinsey Agricultural Services.)

 

Apply the Correct Form

Another possible reason for a lack of response from manganese applications is the form that is applied. Many fertilizer dealers believe they are doing the farmer a service by offering manganese oxysulfate because it costs less than straight manganese sulfate. Even though you can purchase 28% manganese oxysulfate and it may be cheaper, it lacks the effectiveness of 28% manganese sulfate. You cannot use the oxysulfate form to increase measurable available manganese levels in a manganese deficient soil.

Pure manganese sulfate is the best form to use in order to build levels in the soil. Most soils will only show a correct response to its use twelve months or more after an application. Even then, there are certain soils that require several treatments to reach the minimum level. Many of the heavy yellow clay soils are in this category. Any soils subject to water logging should also be suspect.

 

Ensure Reliable Measurement

There are even some soils that are so unusually tight in their natural form that until the physical structure is corrected, a maintenance application will be required every three or so years just to maintain a minimum required level there. The point here is that to assure successful management of manganese levels, some reliable form of measurement is needed.

A big test to evaluate the reliability of a manganese analysis is what kind of measured response the test reflects from the actual amount of manganese that is applied based on the analysis of the material that is used. For manganese, the proper measurement should reflect an approximate pound for pound response after twelve months or more from the time it is applied.

There are specific parameters to be considered when using the guidelines for manganese from the Albrecht system of soil testing. Other tests may imply they can copy the Albrecht System of Soil Fertility, but there is one test anyone can do to prove whether that is the actual case. This is important because reported test numbers for manganese are usually much lower than the actual numbers recorded when using the Albrecht system. This often means farmers and growers whose consultants are used to using other tests will be told they have adequate manganese when the Albrecht system is actually showing the soil is still deficient.

Since reported numbers for soil manganese content can vary widely according to how the test is conducted, desired levels should be based on coordinating field experience and optimum crop response. Using verification based on 80 years of field testing the Albrecht analysis for manganese can identify deficient, adequate, excellent and excessive levels in the soil. Anything less than adequate is going to begin to cause problems.

This is not trying to cast doubt on any consistently reliable test for manganese availability in the soil. It is only meant to point out that the numbers given as deficient, sufficient and excellent may be completely different and usually are on tests from another soil testing laboratory. For that reason, be sure that you or your consultant would know what levels are actually reflected on those tests. And most of all, do not try to arbitrarily apply the guidelines outlined here as reflecting actual soil needs based on numbers provided on other tests. See next month’s issue of Organic Farmer for further guidelines about applying manganese to correct deficiencies.

Neal Kinsey is owner and President of Kinsey Agricultural Services, a consulting firm that specializes in restoring and maintaining balanced soil fertility. For more information please call (573) 683-3880 or go to www.kinseyag.com.

Pros and Cons of Growing Chestnuts

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Chestnut trees once filled the forests in the Eastern U.S. In the fall, people looked forward to collecting the nuts that littered the forest floor. They roasted the chestnuts or used them to stuff their holiday turkeys. At the turn of the 20th century, the chestnut blight hit. No one is positive who imported the original blighted tree or seed from Japan, but the lethal fungal disease was first discovered in 1904 in New York City. By that time, nurserymen had shipped Asian chestnut trees all over the states. Within 50 years, the blight had forever altered the Eastern U.S. forests. What had once been an important forest tree was reduced to a multi-branched shrub that rarely produced nuts.

The blight die-out especially affected the great chestnut forests of the Appalachian Mountains and the people that lived there. It caused a big problem in the mountain people’s food chain. It wasn’t only the loss of nuts as a food source for the human residents; it was a loss of food for the forest animals that depended on the high-carbohydrate fall nuts. The Appalachian people also depended on those animals as food for their tables.

 

Western Growers

Living and farming in western states is a definite pro as far as growing chestnuts. California, Oregon and Washington are largely a chestnut blight-free environment. Growers here can even plant blight–susceptible European chestnut (C. sativa) and their hybrids (C. sativa x C. crenata), according to Michigan State University Extension.

Carol Porter is one such western grower. She got interested in growing chestnuts after reading an article about them in National Geographic. That was in the 1980s when Oregon State University (OSU) was giving seminars trying to bring back the chestnut. When chestnuts didn’t catch on with enough growers, OSU’s chestnut research dwindled.

But Porter stuck with it. She and her late husband, Bill, planted 12 acres of chestnut trees in a back area of their Sweet Home, Ore. property. They put in dripline with headers to each tree. For the first seven years, the Porters irrigated their trees. Once the taproot found water, Porter said, the trees no longer needed irrigation.

Carol Porter holds Nevada chestnuts.

 

Pests and Diseases

Plant chestnuts in well-drained soils to prevent fungal root disease. Stay away from wet soils that are low in oxygen. If Phytophthora root rot takes hold, it affects the roots and crown of a tree (the area where roots and trunk meet.) The disease can be transported on nursery stock or may already exist in soil from other trees. Chestnuts may die in wet soil, even without root rot. They simply do not do well in poorly drained soil. If your soil contains a lot of clay, amend it with copious amounts of compost and plant trees on mounds or slopes.

To prevent sunscald, paint trucks with white paint.

European shothole borer (Xyleborus dispar Fabricius), also known as the pear blight borer, is the main chestnut borer pest in the Pacific Northwest. The small, dark-brown beetles attack the bark of weakened branches. The larvae are white, legless and about 0.16 inches long. They overwinter as adults. When the many adult female beetles emerge during the first warm days of late winter or early spring, they leave behind holes in the bark that resemble buckshot damage. The male is flightless and stays behind in the tree. Although these beetles mostly attack injured, weakened and stressed plants, they may also attack healthy trees that grow near blocks of infected trees.

To help prevent shothole borer infestation, avoid planting chestnuts near abandoned orchards, recent clearcuts or unhealthy forests. Protect against sunburn. Cut out damaged branches and burn them.

As far as chestnut nutrition needs go, do a soil analysis in the spring followed by a tissue test in July or August. If potash is needed, apply in fall so winter rains carry it down to the roots.

Porter has had few issues with her chestnuts, except for animal pests.

“I was kind of naïve,” Porter said. “I don’t remember anyone telling me that every creature likes the nuts.”

Deer, elk, squirrels, turkeys and other birds devoured her chestnuts. She searched for a solution and was told by experts there were two things she could do: Build a tall fence to keep out at least the bigger animals and plant an orchard closer to the house where human activity would help keep animals at bay. Porter did both. Between 1994 and 1995, she planted a new orchard within view of her house and fenced it. She planted 173 trees on a 50 X 50-foot grid in the three-acre block. The trees began producing after seven to eight years, which was also when she quit irrigating them.

Chestnuts on the ground at harvest time.

 

Marketing

Although Porter started out planting the colossal variety for their kernels and the Nevada variety as pollinators, she has discovered that she prefers Nevada. Colossal is a Japanese-European hybrid. Its nuts are large, but they tend to have several smallish kernels in each shell. Nevada is a medium-sized nut, with only one larger kernel inside. Porter said Nevada nuts are sweeter. The nuts she sells to the public equal 15 to 16 per pound in size.

Porter and her late husband previously raised cattle in Colorado. In Sweet Home, Porter raises cattle and hogs. She feeds any small or split chestnuts to the livestock. At the local farmer’s market, she sells USDA beef and pork along with chestnuts. Porter has a liquor license, and sometimes she sells chestnut beer made by a Portland microbrewery that buys nuts from her. She connected with the brewer because he was looking for a gluten-free beer to offer customers along with the gluten-free menu items at his restaurant.

Porter and Randy Coleman of RC Farms in McMinnville, Ore. started West Coast Chestnut Growers Association. Around 30 growers from western states joined, but the members realized they needed to band together nationally with other growers. They reorganized into the non-profit organization Chestnut Growers of America which attracted around 100 growers. Their goal is to promote chestnuts, share information among growers and support research and breeding work.

The most frustrating thing about growing chestnuts for Porter is the lack of public awareness about the nut – especially on the west coast.

“People here don’t know what a chestnut is,” said Porter, who grew up outside of Boston, Mass. “It’s a wonderful food source. People just don’t know what to do with it. There’s a whole generation that doesn’t know.”

In the Eastern U.S., chestnuts are still popular. In New York City, street vendors sell hot roasted chestnuts. Besides eating the nuts, people also keep them in their pockets to warm their hands, Porter said.

She’s not sorry for sticking with chestnuts, although she does wish there was a bigger market for the nuts in the U.S., especially west of the Cascade Mountains. Porter sells a lot of nuts to people from Europe – some directly from her farm, but most through the farmer’s market.

Porter is in the process of teaching her niece and nephew the ins and outs of farming since they want to take over the farming operation when she retires. They will manage the livestock as well as the chestnuts.

Except for the lack of a booming west coast market, Porter is otherwise upbeat and positive about chestnuts. They have natural tannins in the wood, which helps keep the wood from rotting, she explains.

“It’s a wonderful wood,” she said. “Makes wonderful split rail fencing.”

Other positives? Their longevity. “Chestnuts can live 800 years or more,” Porter said. “They’re a fabulous tree.”

Carol Porter in her Sweet Home, Ore. chestnut orchard.

Centipedes and Millipedes in the Soil Food Web

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Myriapods or myriapoda, such as centipedes and millipedes, are an important part of the soil food web. The word ‘myriapods’ is Greek and translates to myriad (or many) feet. These two types of creepy crawlers work in tandem, but in different ways, to benefit the soil. Centipedes are the hunters, and millipedes the gatherers.

The taxonomic hierarchy goes like this:
1) Animals
2) Invertebrates
3) Arthropods (which also includes insects, spiders, mites, lobsters and crabs)
4) Myriapods.

Besides their many legs, other characteristics of both centipedes and millipedes include: One pair of antennae; Two body segments – a head and trunk; Segmented trunks; Simple eyes, Mandible (lower jaw), maxillae (upper jaw); Respiratory exchange happens through a tracheal system — a series of branched tubes that infiltrate the body and carry oxygen directly to cells.

Centipedes are fierce predators, specializing in insect larvae and are a top predator in the soil ecosystem.

 

Centipedes

Centipedes are the top predator in the soil food web. They have modified legs that work like the mouthpieces of spiders, except the mouth claws on centipedes are tipped with venom.

Using these claws to hunt their prey make centipedes fierce predators. Most are fairly harmless to humans, although a bite from some types is painful, similar to a wasp sting.

Centipedes help keep some pests in check. They specialize in killing and eating snails and grubs, a definite pro for the farmer. On the con side, centipedes also eat earthworms and spiders. To keep things fair in the compost battleground, spiders, in turn, eat them. Centipedes are also a food source for large beetles, snakes, salamanders and opossums.

Some species of centipedes can reach 12 inches in length, although most are .5 to 4 inches. They have poor eyesight. Some soil centipedes are even blind. They move through the soil like an earthworm by expanding their length forward and then contracting to bring the hind part of their body towards the head. This tunneling improves aeriation of soil, allowing water and nutrients to reach the roots of plants.

Centipedes can be good mothers. Some species give live birth, others lay a clutch of 15 to 60 eggs. The maternal-type centipedes wrap their bodies around the eggs, licking them to protect them from fungi. They stay with the eggs, shielding them until they hatch.

Although centi means one hundred, centipedes never develop exactly 100 legs. They always have an odd number of body segments, and with one set of legs per segment, the math never adds up. Their legs can grow back if damaged. More body segments and legs are added with each molt.

Millipedes range in size from less than an inch to nearly a foot in length.

 

Millipedes

Millipedes are the centipedes’ distant cousin. They consume organic materials and are considered shredders, or detritivores. They play an important role in breaking down plant and animal debris (detritus) and are excellent for the soil, eating up to 10 percent of the leaf litter in compost. Millipedes work in much the same way as earthworms, moving nutrients through the soil. Also like earthworms and soil centipedes, their tunneling aerates the soil and assists with water penetration. Millipedes also benefit other soil organisms, working together to turn mulch and debris into nutrient-rich soil. They recycle nutrients at a much higher rate than natural decomposition.

Millipedes are more docile than centipedes. They move slower, and instead of biting as a defense, they roll up into a tight ball to protect themselves. They also secrete a nitrogen gas that is toxic to small insects such as ants. Generally harmless to humans, a millipede’s gaseous secretions might cause skin or eye irritation to sensitive people. Like centipedes, millipedes have poor eyesight and get around by feel with their antennae. They have a special group of hairs on the second and third pair of legs that they use as brushes to keep their antennae clean.

Millipedes lay eggs. In some species, the mother − in others the father − protects the eggs. The hatchlings look like miniature adults, minus all the legs. Some species are legless at hatching. After the first molt, baby millipedes have three body segments and six sets of legs. It takes one to two years, sometimes longer, for a millipede to reach adulthood. Their average life span is 1 to 11 years. The African giant millipede can reach nearly a foot in size and is often kept as a pet. Most species are one to four inches long and dark brown to black in color.

Like centipedes, millipedes don’t live up to their name in number of legs. Milli means one thousand, but most millipedes have only 80 to 100 legs. No millipede species known to science has 1,000 legs. The one that comes the closest is Illacme plenipes, a rare millipede found only in Northern California.

 

A Specialized Millipede

For decades California’s Illacme plenipes was thought to be extinct. First discovered by government scientists in 1928, it wasn’t documented again until the mid-2000s when University of Arizona entomologist Paul Marek, then a doctorate student, found one. In the three-year period from 2005 to 2007, Marek and his team found 17 of the rare millipedes, as reported by National Geographic. All were clinging to the underside of sandstone boulders in a 2.8 square mile area outside of San Francisco.

The female of this little Silicon Valley creature sports up to 750 legs. Males have up to 550. Other unusual notes of interest about this highly adapted millipede are the claws on the ends of its legs – thought to assist in digging and traveling deep underground – and the long silken hairs on its back. The hairs likely help it cling to the underside of rocks and boulders. Even with its myriad of legs, this millipede is small – only 1.2 inches in length. For millipede aficionados, the rare and unusual Illacme plenipes is legend.

There are two less familiar myriapods – the sauropods and symphylans. They are both small, even microscopic organisms, that live in the soil and play their own roles in the soil food web.

A centipede can have many legs, but never exactly 100.

 

Telling Centipedes and Millipedes Apart

Centipedes and millipedes sometimes look similar, but centipedes are flatter. They have round, flat heads and flattened bodies. They are the quicker of the two, undulating rapidly over rough terrain. Soil centipedes are often reddish orange in color but can range from translucent white to dark brown.

Millipedes are cylinder-shaped with a rounded head and body. They have two pairs of legs per segment. One would think with all those extra legs they would be the faster of the two, but they are much slower, with their legs moving in a wave motion on either side. They are most active at night or after a rainfall.

Centipedes live in dark, damp places. This one was found under a large rock after a rainstorm.

 

Where do They Live?

Myriapods are found around the world in grassland, farmland and forests and in every continent but Antarctica. They are even found in deserts, which strikes as odd because they generally dwell in damp, dark places – under logs and rocks, underground or inside mulch or compost piles. Without the waxy substance that coats the exoskeleton bodies of many insects, millipedes and centipedes are prone to dehydration, so they need a moist environment to thrive.

In agricultural soils, shredders such as millipedes can become pests if there isn’t enough dead plant material available. Without detritus available, they will eat live plant roots – adding another check in the compost pro column.

There are at least 12,500 different species of myriapods. Scientists estimate they have creeped along the earth, contributing to soil health, for some 485 million years.

Tightening the Nitrogen Cycle in Organic Agriculture

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Before Haber and Bosch invented atmospheric nitrogen fixation, farmers used manure, compost, cover crops and crop rotations to keep their soils fertile. Farmers relied on biological processes to feed their crops, and limited nitrogen availability often compromised yields. Mineral N fertilizer revolutionized farming, bypassing microbial decomposition to directly feed the crop surplus levels of nitrogen. Virtually unlimited nitrogen availability produced drastically higher yields, but the excess N began polluting groundwater, rivers, wetlands and oceans.

The green revolution demonstrated agricultural crops’ impressive yield potential and heightened consumers’ quality expectations. Modern organic practices seek to minimize nitrogen pollution while attaining yield and crop quality metrics comparable to conventionally produced crops. Carbon-based organic materials provide initial protection against nitrate leaching when first applied; however, once microbes convert organic N to nitrate, it leaches just as easily. Over-applying quickly mineralizing organic fertilizers negates any environmental benefit provided by organic amendments.

 

Keep it “Tight”

The most efficient, environmentally protective fields have “tight” nitrogen cycles, where nitrate levels remain low, yet crops grow vigorously with optimum N concentrations in leaves and petioles1. Since nitrogen fluxes between several biological and mineral pools, traditional soil nitrate testing does not always indicate nitrogen sufficiency or deficiency in organic production. In the best-case scenario, active microbial populations steadily release N to the crop, and healthy root systems quickly absorb nitrate and ammonium before it builds up in soil solution1.

Nitrogen requirements are well understood for most agricultural crops, and N uptake curves usually help guide fertilizer application rates. In conventional production, growers can match the nitrogen uptake curve by adjusting nitrate and ammonium applications to meet the demand at different growth stages. Organic producers don’t have the luxury of matching the crop’s N requirement pound for pound with fertilizer. Organic amendments supply nitrogen in carbon-based forms that must be processed by microbes before becoming available to plants. Bacteria break down amino acids, proteins and peptides, mineralizing organic nitrogen to form ammonium. Other microbes then quickly transform ammonium to nitrate through nitrification. Yield and crop quality largely depend on how closely nitrogen mineralization timing matches the crop’s N uptake curve.

Applied Amendments

While soil quality and environmental conditions influence mineralization, the type of organic amendment applied impacts nitrogen availability more than any other factor. Meticulous soil incubation studies conducted at UC Davis elucidate the nitrogen mineralization patterns driven by commonly used organic fertilizers. Dr. Patricia Lazicki and colleagues identified four main amendment categories based on nitrogen mineralization potential6. Organic amendment categories include (1) yard trimmings compost, (2) manure composts, (3) granular fertilizers and (4) liquids, blood and feather meal and guano-based fertilizers6.

Growers can apply material from one category or another to address different needs throughout the year. Fertilizers with high C:N ratios mineralize slowly compared to materials containing less carbon and more nitrogen. Lazicki et al. found that less than 5% of the total N in yard trimming compost mineralized after 84 days of soil incubation at moisture and temperature levels comparable to California field conditions. Green waste compost has a C:N ratio of roughly 20:1 and contains relatively little N compared to carbon. Microbial growth increases in response to the carbon, but is limited by a short nitrogen supply. Microbes incorporate the nitrogen into their biomass, temporarily removing it from the plant-available pool.

Manure- and animal-based amendments contain more nitrogen and have lower C:N ratios, so microbial growth slows due to limited carbon supply, leaving excess nitrogen available to plants. Soil incubation demonstrated 15% to 30% N mineralization for manure-based compost applications and 35% to 55% mineralization when granular organic fertilizers were used. Category 4, including organic liquid fertilizers, blood and feather meal and guano products, had the highest total mineralization. 60% to 90% of nitrogen applied with the amendment was mineralized after 84 days. Almost all mineralization occurred in the first two to three weeks after application. Several other studies demonstrated similar mineralization rates for organic fertilizers2,3,⁴,⁵.

Organic liquids and animal based products help meet the crop’s nitrogen requirement during rapid growth when the roots take up more nitrogen than baseline mineralization can supply. Adding moderate amounts of liquid organic fertilizer improves yield and crop quality, but excessive use can cause nitrate buildup and leaching. On the other end of the spectrum, applying green waste compost too close to planting can cause nitrogen immobilization and subsequent deficiency in the crop.

Organic amendment categories based on nitrogen mineralization potential. Results show that microbial growth increases in response to carbon, but is limited by a short nitrogen supply (courtesy E. Wingate.)

 

Manage Microbes

Growers can tighten the nitrogen cycle by increasing organic matter, increasing microbial abundance and diversity, and maintaining optimum soil moisture. Soils with low baseline microbial activity are prone to nitrate spikes and crashes when fed organic amendments. The carbon and nitrogen influx can cause a temporary spike in microbial growth, immobilizing N as it is incorporated into microbial bodies. Later, when the microbes run out of food, their populations crash, releasing excess N to the crop. Increasing microbial biomass and diversity buffers the nitrogen supply. Large, robust soil ecosystems contain some populations that are growing and others that are dying. The continuous microbial turnover provides a steady nitrogen supply, reducing the likelihood of nitrogen spikes and crashes.

Providing plenty of labile carbon and nitrogen can increase microbial biomass and stabilize nitrogen dynamics1. Growers can apply green waste compost pre-plant or in the fall prior to spring planting. The high C:N ratio will likely cause initial nitrogen immobilization followed by slow mineralization. Green waste compost contributes very little plant-available nitrogen during the first year after application, but it increases the microbial biomass necessary for steady nitrogen cycling. Cover crops and reduced tillage also increase organic matter and microbial growth.

After feeding the microbes, growers can feed the crop with granular and liquid organic fertilizers that mineralize quickly. Low C:N ratio materials should be applied early in the season and during rapid growth. Apply liquid organic fertilizers at moderate rates every 7 to 14 days during peak vegetative growth. Including a wide range of amendments in organic systems will increase microbial biomass and soil organic matter while providing plenty of plant-available nitrogen when crops need it the most. By carefully managing organic fertilizer use and fostering a robust microbial community, growers can provide all the environmental benefits organic farming offers without compromising crop yield or quality.

Eryn Wingate is an agronomist with Tri-Tech Ag Products Inc. in Ventura County, Calif. Eryn creates nutrient management plans for fruit and vegetable growers to improve yield and crop quality while promoting soil health and environmental protection.

Sources

  1. Bowles TM, Hollander AD, Steenwerth K, Jackson LE (2015) Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape. PLoS ONE 10(6): e0131888. https://doi.org/10.1371/journal.pone.0131888
  2. Gaskell, M., & Smith, R. (2007). Nitrogen Sources for Organic Vegetable Crops, HortTechnology hortte, 17(4), 431-441. https://journals.ashs.org/horttech/view/journals/horttech/17/4/article-p431.xml
  3. Hadas, A. and L. Kautsky. (1994) Feather meal, a semi-slow release nitrogen fertilizer for organic farming. Fert. Res. 38: 165–170.
  4. Hartz, T. K., & Johnstone, P. R. (2006). Nitrogen availability from high- nitrogen-containing organic fertilizers. HortTechnology, 16, 39–42. https://doi.org/10.21273/HORTTECH.16.1.0039
  5. Hartz, T. K., Smith, R., & Gaskell, M. (2010). Nitrogen availability from liquid organic fertilizers. HortTechnology, 20, 169–172. https://doi.org/10.21273/HORTTECH.20.1.169
  6. Lazicki, P, Geisseler, D, Lloyd, M. (2020) Nitrogen mineralization from organic amendments is variable but predictable. J. Environ. Qual. 49: 483–495. https://doi.org/10.1002/jeq2.20030

Boron for Growing Organic Crops

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The previous article provided the first in a series to be published in Organic Farmer on both soil needs and plant response for trace elements or micronutrients.

More often than not, the soils we receive to be analyzed for growing all types of crops are deficient in several micronutrients, but the one that requires constant vigilance to assure the greatest success is boron. Like nitrogen and sulfur, boron can be leached from the soil. So, just as is true concerning sulfur, farmers and growers should test for boron content in the soil and generally expect it to be required to correct soil needs accordingly from year to year.

Although it should be, boron is not usually considered as a necessary addition for growing most crops including corn, soybeans, wheat, vegetables and even pastures. Without adequate boron, more nitrogen is needed in order to produce the same amount of growth. Consequently, it needs to be present in sufficient amounts as plants begin to grow and throughout the growing season. Still, it is always best to apply boron to the land based on actual needs as established by a reliable soil test, not by guessing whether it is or is not needed.

 

Calcium and Boron

Based on the test we use, the minimum boron level in any soil should be no lower than 0.8 ppm. But because it can be easily leached with rainfall or irrigation water, enough material should be applied to build for a higher level, and 1.5 to 2.0 ppm is considered ideal. Excellent boron levels are only most effective when there is sufficient calcium and phosphorous. Though it can still be helpful, there is no need to expect the best response from boron under circumstances where either one of these elements is not at sufficient levels.

In fact, calcium and boron work together in the soil as plants need sufficient calcium to take up adequate boron, and enough boron is needed in the soil to assure that calcium is taken up by the plants. Also, if phosphate is deficient in the soil, boron will not fill the seed or grain to the same extent as would normally be the case.

Though some in plant genetics may disagree, once all the other needed nutrient levels are completely met for producing a desired corn yield, if boron is not kept above 0.80 ppm, the kernels will not fill out all the way to the tip of the cob. It is not plant genetics that cause this problem. In every case, once the nutrients that are lacking have been supplied, even the most “susceptible” varieties fill out completely. How many bushels of corn grain are lost due to that lack, even at ¼-inch of grain loss per cob per acre?

As an all-too-common example, one corn farmer, new to the program, always had problems getting his corn to fill all the way to the tip of the cob. This farmer had low phosphate and deficient boron levels in his fields. We recommended both the needed phosphate and the boron. However, the farmer was convinced by his fertilizer dealer that his soils had adequate P levels and only needed a little starter P. This was also advocated to farmers in the area by the land grant university in the state.

Though sufficient boron was supplied, the kernels at the tips of the cobs still did not fill out completely to the end because the soil lacked sufficient phosphate. When both are deficient, a primary element such as phosphate or potassium should be given the highest priority over any trace element, including boron.

That same farm still uses our program. Once the needed P was supplied and the boron level continued to be maintained, the cobs began filling plump kernels of grain completely to the tip of each ear, and the yield increase from that extra grain is now an annual 30 to 40 more bushels of corn per acre.

Corn lacking sufficient boron. Note the straight cobs and straight rows of grain indicating sufficient phosphate for the crop. A sufficient amount of boron applied in the spring would solve this problem (photo courtesy Kinsey Agricultural Services.)

 

Nutrient Balance

Soils need boron to maximize the size of fruit and seed crops. But this will not happen without adequate calcium. Calcium is necessary to get starch into crop leaves. Boron is needed to get the starch from the leaves to the fruit or the grain. If either is lacking, seed and fruit size will also be lacking.

Consider again: this response will not happen without the proper minimum amount of calcium in the soil. And just having a “good soil pH” does not assure that calcium is adequate enough for the best crop response to boron. It is the soil saturation of calcium that determines how boron will help plants to respond in any soil. When the available calcium saturation is 60 to 70% in a soil, the crop response from using adequate boron is excellent. But on that same soil, if the saturation of calcium is in the 40 to 50% range, the same amount of boron can be toxic to the very same crop. This is why growers should not rely on soil pH as being indicative of enough calcium for the safe use of boron.

A lack of response from boron can also be caused by excessive amounts of potassium in the soil. This situation can cause boron to be tied up and unavailable to the crop from the soil. More specifically, when potassium is over 7.5% of total soil saturation, even if the level of boron has been maintained as needed, such high potassium ties up what would have been normally plant-available boron. In such cases, the crop will suffer from boron deficiency.

Still, the more deficient the calcium saturation is in any soil, the more likely boron toxicity problems will occur. So again, a balance between all the soil nutrients is needed for best results because each nutrient must sufficiently be supplied to do its job in order to help the other nutrients to properly do their job.

Once there is adequate calcium to ensure a safe response from boron, the minimum level in the soil should be 0.80 ppm for general cropping purposes. But once the levels of other nutrients are built up, boron should be built up to between 1.5 to 2.0 ppm. This is the recommended level for alfalfa, but for maximum response from boron on other crops, that same level, when safely achievable, should be considered as ideal.

Clay soils can be built up to the point that boron is sufficient for a crop or even several cropping seasons. Sandy soils are much harder to build, and at times may not even be safe to supply the amount needed to produce the best results. Again, only a reliable soil test can safely provide that critical information. Just guessing can be extremely expensive and very dangerous to the growing crop in such cases!

Too much boron can be toxic to growing plants, so be careful not to apply more than each particular crop can stand at any one time. This is true even when more is shown to be needed for obtaining excellent results.

Using legumes, plants that are very sensitive to boron in the seedling stage of growth, as an example, more than two pounds per acre of actual boron can be toxic, even if calcium is excellent. This is true from the time of emergence up to setting the first tri-foliate leaf, so at least one good soaking rain should occur between such an application and planting.

A citrus grower using our program initially had severely deficient boron levels in his soils. The recommendations made were to correct the needed calcium, which, with ordinary agricultural limestone, will generally take three years to see the full effects for building up calcium levels. Because the calcium was so low and citrus is one of the most sensitive and adversely affected crops to excessive boron, the minimum boron application was recommended to be made with another minimum application six months later.

The grower was warned that in his very sandy soils the boron might never reach ideal. Due to unexpected circumstances, the first application went on in late fall instead of late summer. But the response was so positive that a second application was used in late winter instead of six months later. Where this was done, the fruit was the size of half dollars when the part that did not receive the boron was the size of quarters.

So, in spite of these two applications so close together, the results were so good that the decision was made by the grower without asking anyone to apply a third application in the spring. This time, the trees showed the classic boron toxicity with many brown pustules on the underside of the leaves and began to rapidly defoliate. This would likely have been a big disaster, but an unexpected five inches of rain came in the next two days and washed enough of the boron out to allow the trees to grow another flush of leaves. Though these were mature trees, the grower said it was the best crop he had ever produced there. Had it not rained, it would have likely been the worst.

An example of boron use on grass may be helpful in several ways as well. Samples had been analyzed for the same golf course for a number of years, and the golf course superintendent had been applying everything but the recommended boron. Because of its reported effect on grass by other golf courses, he had been afraid to do so.

But after attending one of our courses and hearing why boron, due to the circumstances involved, can cause problems in one place while working well under different conditions in another, the boron was now going to be applied. Recommendations were made for using a soil application of boron in a dry fertilizer mix.

In about a week, he called to say how much better the grass was already growing than ever before. Due to improved nitrogen utilization, the same thing will happen on pastures when boron is properly used. But before talking about the grass growth, he explained how they could not get dry boron for spreading in the dry mix, but could get Solubor. I cautioned him not to use the full rate if the Solubor was used as a foliar liquid application because it could damage the grass. He immediately replied, “No it won’t!” As a test, we have already applied it to the grass at the nursery; half of one of the greens and half of one of the fairways, and in each case, the grass is just growing greener and taller than ever before.

It then was suggested that he just count his blessings under the circumstances and switch to applying the recommended amount in 12 equal applications over the entire growing season, which he agreed to do.

The next day he called back and exclaimed, “You just saved my job!” Because overnight all the grass they had treated was now “dead” and, thankfully, no more had been applied that way. Foliar boron is fine to use, but it must be applied at a safe rate as a foliar which is much less than that can be done as a normal soil application.

All crops and pastures need adequate boron for maximum nitrogen response (photo by Linda Kinsey.)

 

Soil v. Tissue Testing

Certified organic growers can apply boron based upon proper testing to show there is a need. Borax (11% B) and Solubor (21% B) have always been allowed. Other products may be allowed depending on the material and the rules used for certification.

There are some soils with a pH below 6.0 that still have a sufficient level of calcium to justify a safe and effective boron application. But there are also soils with a pH of 8.0 that have such a low base saturation of calcium that even half the normally safe rate for that soil with a pH below 6.0 could be toxic even with the same crop growing there.

There may be several reasons why, and this is in no way meant to imply anyone is trying to deceive the growers. First of all, too many assume that soil pH is all you need to determine whether boron will be a problem in plants. This is a false assumption. It is not soil pH that accurately determines boron toxicity. It is whether each soil has enough available calcium or not.

We recommend and use plant tissue testing for evaluating nutrient levels in plants. However, in certain cases where micronutrient levels are in question, the plant analysis will come back showing a sufficient level when the soil test shows there is still a need for more to achieve the best results. When it comes to the use of micronutrients, we follow and trust the guidance of the soil tests we use over that of plant analysis.

For example, leaf testing for boron content will tell growers they have enough when soil tests will show boron as still not being there in sufficient amounts for the crop in question.

Growers should be cautious when considering whether their soils need boron or not. There is a great disparity between plant testing and soil testing to show when more boron is needed. For example, when sufficient boron is applied to the soil to reach the ideal level for the best response and growth for citrus, leaf tests from this same grove may report toxic levels in the leaf. This type of warning has been given even when there is no sign of toxicity in the leaves or other plant parts, and, in fact, those who know citrus best would actually choose those trees as the best of the best based on looks, plant response and fruit production.

Boron is an anion, which means it can be leached out of the soil because it is not attracted and held by the clay colloids in the soil. Humus is able to attract and hold some, but generally far too little to keep sufficient boron levels for the crops to be grown there from year to year. Like nitrogen and sulfur, boron can be easily leached from the soil. Consequently, though in some heavier clay soils it is possible to build boron sufficiently enough that, for a year or two, adding more is not necessary, most soils need at least some build up every year.

Although needed in very small amounts, boron enables plants to utilize needed nitrogen, helps increase size in fruit, grain or seed production, and at excellent levels along with adequate copper, helps in preventing and controlling rust and fungus diseases.

Apply boron-based on actual need as determined by soil tests. Using too little or too much can be extremely costly. Do not guess. You cannot manage what you do not correctly measure.

Neal Kinsey is owner and President of Kinsey Agricultural Services, a consulting firm that specializes in restoring and maintaining balanced soil fertility. For more information please call (573) 683-3880 or see www.kinseyag.com.

Boron is necessary for efficient nitrogen utilization. It also takes the starch from the leaf and puts it in the fruit which gives larger sized tomatoes (photo by N. Kinsey.)

Organics Continue to Make Gains in California

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Farm gate sales of California organic agriculture more than doubled in a three year period from 2013 to 2016 as the California organic farming industry saw increases in both acreage and the number of organic growers, according to the UC Agricultural Issue Center’s recently released “Statistical Review of California Organic Agriculture.” The report, which covers the period from 2013 to 2016 shows the total number of organic growers in California grew by 1,020 and the total number of organic acres farmed grew by 927,924, while farm gate sales nearly doubled during the four year period from $1.54 billion in 2013 to $3.12 billion in 2016.

 

By the Numbers

The total number of organic growers in California grew by 1,020 from 2013 to 2016, and the review noted that some growers produce commodities in more than one group. Fruit and nut crop growers led that growth each year, gaining 545 new growers from 2013 to 2016, while pasture and rangeland growers were the least abundant, gaining four new growers.

The Central Coast region, which includes Del Norte, Humboldt, Mendocino, Lake, Sonoma and Napa counties, had the most organic growers in each year of the review.

 

Acreage

The total number of organic acres farmed in California grew by nearly a million acres from 2013 to 2016. Pasture and rangeland produced the most organic acreage each year, but the review shows that there were large up-and-down fluctuations across those years. Overall, pasture and rangeland experienced the highest net gain with 556,947 new organic acres from 2013 to 2016.

Up-and-down fluctuations can also be seen by region for organic acreage. The San Joaquin Valley region experienced this especially, but still saw an overall net gain of 436,198 new organic acres from 2013 to 2016.

 

Farm Gate Sales

According to the review, California organics produced over $10 billion in total revenue from 2013 to 2016. Vegetable crops produced the most revenue each year with $3.77 billion in total revenue from 2013 to 2016, while pasture and rangeland produced the least amount with $9.07 million in total revenue.

The San Joaquin Valley region, which includes San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare and Kern counties, produced the most revenue in each year of the review with $3.22 billion in total revenue from 2013 to 2016. The Cascade-Sierra region, which includes Trinity, Siskiyou, Modoc, Shasta, Lassen, Plumas, Sierra, Nevada, Placer, El Dorado, Alpine, Amador and Calaveras counties, produced the least revenue in each year of the review with $140 million in total revenue from 2013 to 2016.

 

What Does It All Mean?

The statistical trends in the review show large increases in organic growers, acres and farm gate sales. Even though these trends are from 2013 to 2016, Muramoto says he’s still seeing similar trends today in the organic farming industry.

In a recent press release from the Organic Trade Association , the organization stated that organic sales across all states, not just California, were up by 4.6% in 2019 from the previous year. Statistics like these and the ones found in the review made my Muramoto and his team show that consumers are seeking out the Organic label more than ever, and future statistical reviews will be able to provide even more insight into the sector’s growth.

 

Significance of the Review

The late Karen Klonsky, a UCCE specialist who passed away in 2018, spearheaded the initial publications for statistical reviews of California organic agriculture in 1998, six years after the data became available as a result of the California Organic Food Act. Klonsky saw the need for a display of this data for the industry and published reviews that contained statistics all the way through 2012. All previous organic agriculture statistics reviews can be accessed at aic.ucdavis.edu/research1/organic.html.

The review summarized by Muramoto and his colleagues aims to continue Klonsky’s work. “This is the most comprehensive statistical review of California organic agriculture at the state and county levels,” Muramoto said. “Because we use her [Klonsky’s] format, we are able to compare this data to her past reviews.”

The statistics review provides several functions: it helps project future trends of organic crops by commodity groups; influence strategy and policy for organic sectors in each county; and improve researchers’ understanding of specific needs and dynamics of particular organic sectors.

“Accurate data on past trends and the current status [of organic farming] is crucial to develop an effective strategy for the future,” Muramoto said. “For example, the number of organic farms [by county] is highest in San Diego and is still increasing. They don’t necessarily produce the highest revenue per grower because they are mostly small farms; yet they play important roles in local food systems now and probably will in the future.”
As for publications made more recently and future ones, there will be more published by CDFA, according to Muramoto, but there are some continuity issues due to the way data is being collected.

“More recent years are not included [in our report] because the data collected by CDFA changed the crop category in 2017 and again in 2019, so they are not comparable to the data in this report,” Muramoto said. “They did this to reduce the burden of growers in reporting, but it made a data gap consequently. Now, CDFA is trying to match the categories with the Ag census.”

The most recent CDFA reviews of organic statistics are the “California Agricultural Organic Report, 2018-2019” by CDFA and the “2019 Organic Survey” by USDA-NASS.

Creating the Optimum Compost

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Compost offers a wide range of benefits to soils depending on the blend, providing soils with biomass, carbon and nitrogen sources.

In order for compost to work in a soil, it needs to have the proper blend of feedstocks and be tested/treated to ensure proper nutrient levels and microbial activity are present. This article provides insight into the large-scale compost operation at Cal Poly, San Luis Obispo, and how this compost provides benefits to a nearby vineyard.

 

Finding the Right Mix

Kevin Piper, Director of Agricultural Operations at Cal Poly, San Luis Obispo, said in recent video interview that the school’s own operation takes four key components into account when building the feedstocks that go into their compost: carbon to nitrogen (C:N) ratio, percent moisture, bulk density (measured in cubic yards) and texture.

“Good composting practices are important,” Piper said. “We want to know our feedstocks well, and that means knowing the specific components of each.

“Texture is a good thing to incorporate, and normally you’re going to get that with your carbon source,” he continued. “This could be anything from fine sawdust all the way up to rough woodchips. You want to find a happy medium; if you have too much fine texture, you’ll end up with a light mix that has a hard time holding temperatures, and if you have too much rough texture, you’ll end up with a density issue.”

The Organic Compost page on Cal Poly’s website (cafes.calpoly.edu/cal-poly-compost) says that the school’s operation removes solid manure from its dairy, beef, equine and poultry units and incorporates it with green waste from campus landscaping to create its unique blend. The specific feedstock breakdown for the operation, according to Piper, is green waste (55% moisture, 610 lbs/cu yd., C:N ratio of 150,) waste feed/silage (75% moisture, 1,300 lbs/cu yd., C:N ratio of 12,) horse manure (45% moisture, 450 lbs/cu yd., C:N ratio of 40) and separated solids from the on-campus dairy operation (85% moisture, 1,400 lbs/cu yd., C:N ratio of 18.)

“Once we’ve blended our recipe, we want our ideal component ranges to be a bulk density of 800 to 1,000 lbs/cu yd., 40 to 60% moisture and a C:N ratio of 30,” Piper said.

 

Best Practices for Compost

Creating a compost blend can be a complicated and drawn-out process and there are several safety/sanitation measures to keep in mind. If a compost producer’s operation is as large as Cal Poly’s, which Piper said produces 7 to 8 million pounds of manure annually that is then turned into about 3,000 to 3,500 cubic yards of finished compost, vigorous sanitation steps and testing are necessary to retain organic certification.

“Compost producers have to consider California’s regulatory environment,” Piper said. “In this state, we deal with CalRecycle and the Regional Water Quality Control Board, both of which have regulatory requirements for composting facilities. One of the main things to keep in mind when setting up an operation or composting in general is not to do it next to a wellhead or within a couple hundred feet of a live stream. This can pose issues of runoff.

“Another good [sanitation] practice is preventing cross-contamination by cleaning machinery between handling raw feedstock and ongoing/finished compost,” Piper continued.

Maintaining certain levels of microbial activity and nutrients within compost can also make or break an operation. Testing of temperatures and the product itself needs to be conducted before anything is sold. If a compost blend is not ready for use, according to Piper, it can be dangerous to incorporate into plants because of the potential for nutrient stealing.

“We have a pathogen reduction phase (PRP) in our windrow process,” Piper said. “We use short and long temperature gauges to get an idea of what is happening on the interior and exterior level of the compost pile. Once we’ve reached a temperature of 131 degrees F during the PRP, we have to maintain that temperature for 15 days and turn that windrow a minimum of five times. When there is a 20-degree differential between the interior and exterior gauges, we know it’s time to turn.”

Piper said that interior temperatures cannot exceed 150 to 160 degrees F in order for microbial activity to remain undisturbed. If they do, internal moisture conditions can become altered.

“When pulling back some of the compost after checking the gauges, we want to see a layer of white mycelium growing as it shows we have the right moisture conditions and a happy environment for beneficial organisms,” Piper said.

Before sending off finished compost samples to a certified laboratory, operators have the ability to conduct one last test to ensure for a stable product.

“We use a Solvita test,” Piper said. “It allows to test what we consider a finished product for ammonia and CO2 levels. If the test shows reassuring results, we can send it off to a certified lab that is tied with the U.S. Composting Council’s Seal of Testing Assurance (STA).”

According to the U.S. Composting Council’s website, the STA program is a “compost testing, labeling and information disclosure program designed to give you the information you need to get the maximum benefit from the use of compost.” Any grower looking to purchase compost for use in their own farming operation should look for the STA on a finished product.

Interior temperatures for compost cannot exceed 150 to 160 degrees F in order for microbial activity to remain undisturbed (photos by K. Piper.)

 

Grower Usage

Jean-Pierre Wolff, principal owner of Wolff Vineyards in San Luis Obispo, Calif., explained in a phone interview his own usage of compost in his soils and the benefits it has provided him.

“I’ve been applying compost postharvest for 20 years and apply 1.5 tons per acre,” Wolff said. “It takes several years for compost effects to take place in terms of mineralization. In my case, in the first 10 years, I was mixing compost with gypsum. Now, I’ve switched to 100% compost to give priority to the carbon content. The benefit of the nitrogen content is a slow leaching, which has been a good approach for us in the vineyard to have a slow and steady feed of nutrients. It also increases microbial activity due to the higher quality of compost.”

Wolff switched to using Cal Poly’s compost mix in recent years for multiple reasons including its close proximity to his vineyard.

“Years ago, I used dairy farm compost from the Central Valley,” Wolff said. “Because of the transportation costs, I switched to green compost from Santa

Barbara county. Now, I use Cal Poly’s. I switched to them because they’ve gone through a lot of upgrades on their compost equipment and they also offered training classes. Close proximity was a big part of the decision.”

Even though the use of compost has been working out for Wolff’s vineyard over the years, he made it a point to note a couple of major tips when using and buying compost.

“One area which I think can be problematic because of climate change is that it [compost] only works well with areas of normal rainfall,” Wolff said. “I proved this during the latest drought. Utilizing drip irrigation just does not have the same flushing affect for nutrients into the soil as rain does. The microbe activity of freshly applied compost diminishes if this is the case.

“Not all composts are created equal,” he continued. “The whole business of it starts with the quality you get. It sounds fundamental, but it’s key. Always get compost from a reliable source.”

Producing and using compost is a complex process for both sides, and patience is required. Producers have to ensure that their final product is up to par (i.e. good feedstock sources, properly heat-treated, adequate nutrient levels and absence of any harmful compounds) and growers need to ensure that they are buying from the right source and utilizing good compost practices themselves.

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