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California Comeback Plan Proposes Millions in Funding for Cannabis

A new state-level proposal looks to provide a $100 million General Fund in grant funding for local governments to complete environmental studies, license reviews and mitigate environmental impacts for cannabis.

The plan, proposed by Governor Newsom on May 14, 2021, is being labeled the “California Comeback Plan” and supports a broader effort to transition cannabis businesses into the regulated market, a reduction in barriers to entry for small businesses and a sustainability pilot program. The plan also proposes a Deputy Director of Equity and Inclusion to lead state efforts to address the impacts of the War on Drugs and allocates nearly $630 million in cannabis tax funds to public health, environmental protection and public safety initiatives.

 

Transfer to Regulated Market

It has been historically difficult for cannabis licensees to transfer from a provisional license to the regulated market due to disruption of California’s environmental commitments.

Currently, about 82% of licensees are provisionally licensed. Thus, a program that targets jurisdictions that have high numbers of provisional licensees across the supply chain is necessary.

The program, called the Local Jurisdiction Assistance Grant Program, will provide funds intended to aid locals in more expeditiously reviewing provisional licensee local requirements for cannabis, notably those related to the California Environmental Quality Act. These funds can be passed through to licensees for things such as mitigation measures, including those related to water conservation. The state can more rapidly transition provisional licensees to annual state licenses once these requirements are met.

“This grant funding aims to serve local governments and a significant portion of the provisional license population, including a number of small businesses and equity operators,” said Nicole Elliott, Governor Newsom’s Senior Advisor on Cannabis. “We are committed to maintaining stability across the cannabis supply chain, supporting our local partners and transitioning provisional licenses into annual licensure more swiftly without sacrificing California’s environmental commitments.”

The funding Governor Newsom’s plan is proposing, calculated based on provisional licenses issued by the state, would be divided into three categories:

  • Category 1 – 25%: top eight jurisdictions allowing cannabis cultivation.
  • Category 2 – 25%: top eight jurisdictions allowing manufacturing and the top 8 jurisdictions allowing all other cannabis activities, except events.
  • Category 3 – 50%: additional funding for jurisdictions that qualify for Category 1 or 2 and are also implementing local equity programs.

The provisional license plan is currently set to end on January 1, 2022, while the California Comeback Plan proposes allowing provisional licenses to be issued till June 30, 2022. The catch is that licensees looking to continue holding a provisional license past the current end date comply with explicit environmental requirements laid out in the Governor’s plan. Additionally, the plan mandates the Department of Cannabis Control to specify through regulation what progress is required to maintain a provisional license. The licensee can continue to maintain a provisional license as long as measureable progress is being made to achieve annual licensure.

 

Sustainable Pilot Program

The California Comeback Plan also proposes $9 million in funding for a Sustainable California Grown Cannabis pilot program, which will incentivize licensed outdoor cannabis growers to participate in the collection of data to benchmark best practices that reduce the environmental impact of cannabis water and energy use, pest management and fertilizer practices, and to enhance soil health.

The purpose of the pilot program is to establish science-based data for the future inclusion of cannabis in current and future state and national voluntary programs to advance environmental stewardship and to develop and advance Best Management Practices for Sustainable Cannabis Growing. However, some California growers are skeptical of the plan’s agenda.

Justin Eve, owner of 7 Generations Producers and a USDA-certified organic cannabis grower, believes that the program will appeal more to pharmaceutical companies as an incentive than it will to agricultural cannabis growers. “We see this carrot that they’re waving,” he said. “Here’s some free money or a way to be sustainable or whatever that is, but we ultimately know that the only people that will hold up to their regulations that they’re imposing will be these larger corporations and big pharma. They’re not telling people what their true intentions are.”

Eve noted that pharmaceutical companies have been trying to push California away from industrial cannabis production and that the state is missing a key opportunity for agriculture. “I think [it’s a] great program, but the unfortunate thing is that they’re putting so much emphasis on pharmaceuticals that they’re missing the opportunity of how this crop could be so much more than just a drug to get everyone high recreationally.”

 

New Position Opens

The California Comeback Plan proposes an additional position within the Department of Cannabis Control, a Deputy Director of Equity and Inclusion, to serve as the lead on all matters of the Department pertaining to the implementation of the California Cannabis Equity Act. The Equity Act provides funding for local jurisdictions to develop and operate local cannabis equity programs that focus on the inclusion and support of individuals in California’s legal cannabis marketplace who are from communities negatively or disproportionately impacted by cannabis criminalization.

The Deputy Director of Equity and Inclusion would be the Department liaison for local equity programs created to support and reduce barriers to entry for those negatively impacted by the War on Drugs and would also work directly with the Department Director to further incorporate equity and inclusivity into policies and operational activities throughout the Department.

 

Updated Tax Allocations

More than $629 million in cannabis tax funding will be available for public health, environmental protection and public safety initiatives, a 41.9% increase from the Governor’s Budget estimates in January, according to the Plan. 60% ($377.5 million) of the tax funding will go toward education, prevention and treatment of youth substance use disorders and school retention; 20% ($125.8 million) will go toward clean-up, remediation and enforcement of environmental impacts created by illegal cannabis cultivation; and another 20% will go toward public safety-related activities.

The Department of Cannabis Control was formed on July 1, 2021, and combines the cannabis licensing and regulatory functions performed by the Department of Consumer Affairs’ Bureau of Cannabis Control, the California Department of Food and Agriculture’s CalCannabis Cultivation Licensing Division and the California Department of Public Health’s Manufactured Cannabis Safety Branch.

California Olive Ranch Makes Move into Organic Market

It was with three goals in mind that California Olive Ranch decided to transform and dedicate its olive acreage in Oroville, Calif. to certified organic.

The olive oil production operation is award winning on the international level, with a domestic market that reaches across the nation.

With super-high-density olive orchards in Dunnigan, Artois, Oroville and Corning, the company is known for having one of the oldest super-high-density orchards in the world, established in 1999.

“Our varieties are mainly Arbequina and Arbosana, and we have a processing plant and cold press mill in Artois,” said Clayton Handy, the company’s agronomist, who is in the process of earning his Master’s Degree in Agronomy/Regenerative Agriculture from California State University, Chico.

California Olive Ranch CEO Michael Fox and the company’s board made the decision to use the Oroville site as “test acreage” in the move from conventional growing practices to certified organic.

Handy is on the forefront of this transition as he is passionate about allowing the soil and trees to work symbiotically as nature intended.

“We started the three-year process to become certified organic in 2020,” he said. “The company had organic production previously, moved away from that practice, but made the decision to start back up.”

 

Holistic Approach

Handy explained the test-acreage in Oroville has three prime objectives: to regenerate the soil and produce organically grown olives which are pressed into organic olive oil.

A third goal is what Handy refers to as a holistic approach and creating a self-sufficient system.

“It’s really a theory right now, but one we would like to prove as beneficial both to the orchard and financially,” he added.

The theory goes as such, according to Handy: a great harvest can be the by-product of a very healthy, symbiotic tree/soil system.

“This system is one that requires much less input from the grower because the relationship between tree and soil is regenerative, constructive and co-beneficial,” he said.

 

Transition to Certified Organic

California Olive Ranch is just starting the five-step process of transitioning to organic olives. The USDA organic label is backed by a certification system that verifies farmers or handling facilities located anywhere in the world comply with the USDA Organic Regulations. Certification entails the five steps of first developing an organic system plan and second implementing that plan and having it reviewed by USDA.

Third is to receive a comprehensive “top to bottom” inspection on-site by a certifying agent.

The fourth step is having a certifying agent review the inspection report and finally receiving a decision from the certifier.

“If an operation complies with the rules, the certifying agent issues an organic certificate listing products that can be sold as organic from that operation,” according to the USDA.

Handy’s olive-growing philosophy aligns with organic and regenerative production, Handy said.

“I’m excited to see where this effort goes,” he added.

A certified organic orchard is limited on what products can be used to control weeds and pests. Products are required to be certified by the Organic Materials Review Institute (OMRI), an international nonprofit organization that determines which input products are allowed for use in organic production and processing.

“For our Oroville orchards, that means instead of spraying our tree strips for weed control, we are using cover crops and rotary spring-arm mowers,” Handy said. “In addition, chemical fertilizers are out, and the company is using fish emulsifier through fertigation as its fertilizing agent.”

He goes on to explain, “We almost want organic to be a by-product of a very healthy system, so our primary objective is overall soil health.”

The Oroville orchard’s soil has undergone testing to see where its biology levels currently stand.

“We need to know how well we are doing in quantity and diversity of the microbes in our soil, also the fungal to bacteria ratio. We need an overall baseline on how we are doing,” Handy said. “We are hoping in time to see an increase in biology within the soil.”

Biology in the soil will work for you, he goes on to say, as there are a handful of bacteria that can fix atmospheric nitrogen, all day long.

“But are they in your soil,” Handy asks. “Biology in the soil can help place all the plant’s needful nutrients into the plant, we know that, but in most conventional ag systems, we are lacking that soil biology because we spray pesticides and herbicides and put on synthetic nitrogen that is hot and burns a lot of the biology out of the soil.”

Plants as autotrophs make an abundance of photosynthate that has simple carbohydrates and proteins, and much of that is released into the soil via the roots.

“Root exudates contain the simple carbohydrates and proteins and does so in order to feed the microbiology in the soil, and in return, the microbiology can make available the nutrients that are needed by the plant,” Handy explained. “In fact, there is a chemical signal found in the exudates that the bacteria and fungus can respond to and know what nutrient to provide back to the tree. This happens in nature constantly, but the challenge we have in conventional ag today is that the natural system has been weakened.”

This weakness, said Handy, comes about from deep ripping of the soil, fumigating, spraying and applications of fungicides, herbicides and synthetic fertilizers.

“The more we do these practices, the more we are chained to them because it creates a system void of microbes,” he added. “I like to call them trees on life-support.”

In-row cover crop growing at the California Olive Ranch olive oil orchard test-acreage in Oroville, Calif.

 

Cover Crops

California Olive Ranch is working to regain the natural biology, both in diversity and quantity.

“We can do that by increasing the amount of green cover on our fields. So, we plant a very diverse cover crop, diversity being a key,” Handy said.

According to Dr. Christine Jones, soil ecologist and cover crop specialist and founder of Amazing Carbon in Australia, multi-species covers in orchard and vineyard inter-rows provide the perfect vehicle to capture and store soil carbon, increase water-use efficiency, improve the nutrient density, flavor and keeping qualities of produce and reduce the incidence of pests and disease.

“Dr. Jones’ suggestion in cover crop diversity is eight-plus species,” Handy added. “That includes nitrogen fixers, other broadleaves and grasses.”

This year is the second year the Oroville test-acreage has been planted in diverse cover crop.

“We planted in the fall in anticipation of a good rainy season so we have a good stand of cover crop,” Handy said. “That is one thing we can do to increase biology.”

In addition, the ranch is working to maximize the plant matter on top of the soil.

“That plant matter will eventually become carbon, and releases an abundance of root exudates into the soil, what is referred to as liquid carbon, and we want that in the soil, in the system,” Handy explained.

The ranch tries to stall mowing until the cover crop reaches ‘boot-stage’ to maximize growth.

“What you see on top is what you would see in the ground,” Handy added. “This adds organic material, and that breaks down into organic matter to feed the soil. As you increase organic matter, you also increase water retention. The formula is something like for every 1% increase in organic matter, you have 25,000 gallons of water retention.”

In a study at UF/IFAS Extension, the research team said just like a sponge, soils with high organic matter and aggregates can absorb and hold water during rainfall events and deliver it to plants during dry spells.

USDA Natural Resources Conservation Service states that “for every 1% increase in soil organic matter, U.S. cropland could store the amount of water that flows over Niagara Falls in 150 days.”

Cover crops also help break up the soil and help with water absorption.

“You can think of each blade of grass as being a straw and providing a vehicle, a pathway for water infiltration and absorption into the ground,” Handy said. “In time, you can really increase your water infiltration. We don’t want anything to sheet off or suffer erosion.”

He goes on to say that the more you can increase life in the soil, the higher and faster the infiltration rates.

“For us, this is still all in theory as this is only the second year we are implementing these practices,” Handy said. “But we have seen the studies, and we know there are things we can do to increase soil health, and soil health is determined by the amount of biology you have working for you in the system. To have that, you need carbon, and in order to have carbon, you need a source.”

For the test-acreage, that means cover crop and compost.

“Those are the two primary sources of carbon. We put on 2 tons of vegetative compost per acre. We also did a trial of sheep grazing on 20 acres of the Oroville acreage, and we found it to be very successful,” Handy said.

The sheep program provided two-fold benefits through grazing and natural fertilizers from the ruminants. Handy said they plan on increasing the sheep grazing program due to its success in the trial.

“Although what we are working towards right now is just in theory, if we are going to go the organic route, we are going to go the route of a holistic system approach where we specifically look at the system as a whole to increase its overall health, to decrease the need for input and increase the quality of the overall product,” Handy said.

Soil Fertility Considerations for Growing Organic Tree Crops

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There is a rule all growers should seriously consider: “You can’t properly manage what you don’t correctly measure.” When it comes down to growing tree crops organically, there are so many soil types and so many different trees used for different purposes that most growers are led to believe that there can be no basic program to use for growing trees. So, perhaps the first question that needs to be answered is can a basic fertility program for growing trees in general even be properly established, let alone correctly measured?

Every organic grower would likely agree with the concept that soil biology, the plant roots and all that supports them is the foundation for growing organically. What type of soil environment works best in such cases?

To answer that, consider what the most important needs for life are where trees are concerned.

 

Basic Tree Needs

What is needed for life itself? Four needs to consider are proper shelter, food, water and air. But to supply air, water, “food” and even proper shelter for the roots of trees, what is necessary?

Of these needs what should be considered as the order of least importance for trees? Physical shelter would likely be the least important requirement for trees growing in their proper habitat. Food is necessary, but not as essential as water in terms of which one trees can go without for the longest time. But of these four needs, air is the need that takes on the most importance for life itself. Air provides the oxygen we need and the carbon dioxide that plants need. When we lose access to fresh air, life will cease in a very short time.
And even though trees grow with air all around them, sufficient air in the soil is still a critical factor. Without proper soil aeration, the microbes and other soil organisms cannot function as they should to provide nutrients from the soil to the trees. So, the point here is that without the proper amount of air in the soil, trees do not function as well as they should.

Textbooks on soil fertility report that based on physical structure, the ideal soil contains 45% minerals, 5% organic matter, 25% water and 25% air. And when soils measure up to those numbers, anyone who recognizes the best soils will agree that such is the case. But most soils throughout the world do not have those most favorable conditions.

In fact, most sandy soils, just left as they are, have too much air space, which adversely affects water holding capacity. Such soils need more water and less air to be most effective. On the other hand, clay soils tend to hold too much water and not enough air to be most effective for growing trees or any other types of plants. These are not ideal soils with a good balance of air and water. And in such cases, there are only two real choices: grow trees and let them do the best they can, or change the air to water relationships based on the measured needs of each soil.

Soils closer to the ideal physical structure are also those that are closest to ideal in nutrient availability (courtesy Rex Dufour, NCAT.)

There is only one way to effectively change the amount of pore space in each soil. That method is to establish a more desirable physical structure by the use of the proper nutrients that affect the porosity (air to water relationship) of each soil.

There are four principal elements that exert the most influence upon the relationship of air to water in soils where trees or other plants typically grow. These four elements are calcium, magnesium, potassium and sodium.

Of the four, calcium is the key element for increasing soil porosity. Calcium causes the clay particles to clump up or flocculate, which increases the pore space in the soil that determines the general balance between air and water. Magnesium, potassium and sodium do the opposite job in the soil. All three will disperse the clay particles in the soil and cause a reduction in pore space.

For sandy soils, maximize magnesium and potassium to excellent levels, which will reduce air space and increase water holding capacity. For clays, we need to maximize allowable calcium which increases pore space and maximizes aeration needed for the biology to function best there.

In effect, this means using soil chemistry to correctly feed the soil what it needs which naturally regulates the space needed for air and water in each soil. Therefore, the use of soil chemistry to supply the right amount of missing nutrients that help feed the plants is the correct way to achieve the ideal physical structure, which then provides the best balance of air and water in each soil. What this does is to effectively build the most conducive environment for soil organisms which are the key to nutrient uptake by trees and all other plants.

 

Ideal Soils

The ideal soil is described in terms of its physical condition. The physical condition determines how well the biology of the soil can do what is needed for the plants. The solid portion of an ideal soil has roughly 45% minerals and 5% humus. The other half of an ideal soil is pore space. Half of that pore space should ideally be filled by water and the other half with air. However, that physical condition is influenced by the chemistry of the soil, which can be measured using specifically designed soil tests to do so.

There are always certain parameters that must be met to have the most ideal physical structure, which then enables any soil to do its best. That structure is determined by the nutrient makeup of each soil. When the soil nutrients are properly provided, the physical structure will be closest to ideal. Or in other words, the soils closer to the ideal physical structure are also those that are closest to ideal in nutrient availability. Soils cannot have one without the other. When accurately measured, the physical structure backs up the ideal nutrient level, and the ideal nutrient level of the four elements that principally affect soil structure will only be there in the right proportions when the physical structure is also correct.

The question posed at the beginning of this article was can a fertility program for trees in general even be properly established? The answer is provided by studying the nutrient makeup of what is defined as the ideal soil.

Since trees are grown on all types of soils, from very light sands to very heavy clays, and for so many different purposes, how can anyone possibly establish what provides the best fertility for trees? In such cases, perhaps too many people try to put the cart before the horse. For fertility considerations, first concentrate on general principles of fertility that all trees need, then on any additional specifics for different varieties and purposes.

Test where the very best trees of each type grow, where their growth is just average and where the worst problems with growth occurs. See what the best has in terms of nutrient levels that the others do not. Then begin to correct and build the soil to reflect the levels that grow the best trees. If the correct type of materials is used to build fertility levels in each soil, then as the soil test numbers get closer to those where the best trees grow, they begin to do better. In other words, the closer those soils begin to conform to what is needed, the closer the trees will perform as the better ones do.

There is good reason as to why trees do well on some soils and not on others. Two clients who grow English walnuts, one from central California and one from northern California, provide a good example to help illustrate this point. Both clients wanted to grow more walnuts, but had stopped planting because the soils that were left were classified as unsuitable for growing walnuts. Both were familiar enough with the fertility program so that when it came to advice on the proper approach, their confidence was sufficient to follow through. So, when it was shown that manganese was the most critical deficiency on those soils when compared to soils that grew profitable walnuts, though each had very different soils, each applied a sufficient amount of manganese along with the normally needed fertility. The soils previously considered as unsuitable grew excellent walnuts, with top yield performance from the trees.

A basic fertility program for trees should be considered as follows. First provide adequate amounts of N, P, K and S for producing the crop. Next, measure and correct the needed levels of calcium and magnesium. Then, build the essential micronutrients to reach the minimum requirements. Once these needs have been satisfied, then consider the special needs for growing trees that set them apart from other crops.

This topic will be addressed in Growing Organic Tree Crops – Part 2 in the next issue.

Neal Kinsey is owner and president of Kinsey Agricultural Services, a consulting firm that specializes in restoring and maintaining balanced soil fertility for attaining excellent yields while growing highly nutritious food and feed crops on the land. Call 573-683-3880 or see www.kinseyag.com for more information.

Put Soil Microbes to Work

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In the March 2021 issue of Organic Farmer, Lloyd et al. 2021 discussed nutrient release rates from commonly found organic fertilizers with a focus on plant-available nitrogen. Nitrogen (N) is well known for driving crop yield and quality goals and is widely used by organic farmers of all types. However, organic growers uniquely rely on materials that are derived from complex plant and animal byproducts and meet their crop nutrient goals through composts, manures and specialty liquid fertilizers derived from grocery store waste, soy hydrolysate, corn steep liquor, etc. This approach contrasts with conventional fertilizer sources that are man-made and easily dissolved as a simple salt in water. Thus, organic farmers rely on nutrients that are bound to complex carbon molecules to drive crop production.

A key point made in the article is that soil microbes are critical players for “releasing” the nutrients that are applied with composts, manures and other organic sources. Very briefly, nutrients (e.g., nitrogen) stored on organic fertilizer materials are primarily released when a microbe decomposes, or consumes the carbon structures as a food source, and liberates the nutrients for the plants to use in a process called mineralization. If the organic fertilizer material is not acted upon by the microbes, the plant will not benefit from the bound nutrients within a reasonable timeframe (Figure 1).

Organic fertilizer sources contain a mix of carbon and plant nutrients. In most cases, the nutrients must be first “unlocked” from the fertilizer source by soil microbes to allow for plant uptake.

Figure 1: In organic production and other farming systems that depend on plant nutrients attached to a carbon source (e.g., compost, manures, teas, blends, etc.), microbes must actively process the inputs before the plants can get access to the nutrients.

 

Nutrient Release Rate

One challenge in organic production is ensuring that nutrient release rates from the fertilizer source are in line with plant demands. If the microbes are failing to keep up with the crop, nutrient deficiencies can result. For example, only 5% to 20% of N in a compost application is immediately plant available (Vogtmann et al. 1993). Of course, these release rates vary depending on organic fertilizer source, local climate and time of year. These facts also demonstrate that organic fertilizer sources are prone to nutrient demand lags. If only 5% to 20% of your compost N is plant available in the first year, then up to 95% will only be available at some time later down the road! This lag in nutrient availability can cause serious challenges when trying to meet market demands and annual contracts.

A good question here is: “How do I ensure I am getting the maximum crop nutrient benefit from my organic fertilizer program? The answer? Put your soil microbes to work.
The next section describes how microbes serve as an important mediator between the organic nutrient source and the end destination in a crop system: the plant. We will walk through how microbes are crucially linked to your soil fertility and crop performance and discuss the ways you can “manage” your microbes to help your fertilizer program work more efficiently.

 

Sleepy Microbes

Studies show that most of your soil microbiome (e.g., soil fungi and bacteria) can go dormant when things do not go their way. Case in point, many microbes go to sleep when they are hungry. This “sleep” phase is a key survival mechanism for microbes. However, your plants cannot access the nutrients they need from the organic fertilizer program when their partner, the microbes, go dormant. Research consistently shows that dormant soil microbes respond readily to a food source and, when fed properly, can then go to work decomposing and synergizing with your choice of organic fertilizer.

“Manage” your microbes by providing them with a food source. A microbial population that is abundant and diverse in the soil can act upon your fertilizer input program, which can drive a more consistent nutrient release rate for the crop.

Organic growers in particular have consistently reported improvements in crop performance when adding a microbial food source to the crop production plan.

 

Manage Your Microbes

Manage my what? Ag scientists and growers alike are just beginning to tap into the potential of a better managed soil microbiome. Organic growers in particular have consistently reported improvements in crop performance when adding a microbial food source to the crop production plan. There are many options to wake up your microbes and put them to work on your farm, particularly if you are using organic fertilizers. Reviewing your choices with a trusted advisor is a great way to find the microbial food that best suits your operation and logistics.

Organic farming, or any type of farming that sources plant nutrients from carbon-bound materials like compost and manures, is uniquely positioned to improve crop yield by ‘waking up’ the soil microbiome with a labile food source. A well fed and robust microbial community has the expanded potential to process your organic inputs and can help ensure your crop is getting the nutrients it needs to achieve your unique yield and quality goals.

Dr. Karl Wyant currently serves as the Vice President of Ag Science at Heliae® Agriculture where he oversees the internal and external PhycoTerra® Branded Product trials, assists with building regenerative agriculture implementation and oversees agronomy training.

 

References

Soil Microbes in Organic Cropping Systems 101 – http://eorganic.org/node/34601
How Much N Can You Expect from Organic Fertilizers and Compost? – https://organicfarmermag.com/2021/03/how-much-n-can-you-expect-from-organic-fertilizers-and-compost/

Additional Resources
Soil Health Institute Blog – https://soilhealthinstitute.org/resources/
PhycoTerra® Blog – https://phycoterra.com/blog/

Mycorrhizal Fungi for Plant Systems: The How and the Why

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Dig up the roots of a healthy plant system and you’ll find an array of webbed filaments attached to the roots and soil. Those are mycorrhizal fungi, and they’re constantly at work promoting root system growth, nutrient efficiency and water absorption.

Mycorrhizal fungi are critical for the health of organic and conventional planting systems, fostering an important symbiotic relationship with the plant. But how do these fungi work and why do they work?

 

Symbiosis with the Plant

Mycorrhizal fungi and plants work together in the soil in symbiosis, where both the fungi and the plant interact with and benefit from each other. Historically, this relationship was hypothesized to have formed as a result of aquatic plants transitioning to terrestrial systems and accessing nutrients in rock substrates and/or soils.

“The plant gets nutrients and water, and the fungus gets carbon,” said Dr. Cristina Lazcano, assistant professor of soils and plant nutrition at UC Davis. “The fungus actually cannot survive without establishing this interaction with the plant. It needs to colonize a plant to produce spores and the next generation [of fungi].”

Dr. Lazcano said that the symbiotic interaction between the plant and mycorrhizal fungi is normally established when there is a need from the plant. “The interaction is expensive for the plant,” she said, noting that the plant will not interact with the fungi if it doesn’t need to. “The plant needs to pay back the fungus in the form of carbon that the plant photosynthesizes.”

Plants typically need to interact with mycorrhizae when there is low soil nutrient availability, according to Dr. Lazcano. She said that grower practices such as over-fertilizing to counter low nutrient levels in the soil will create a poor environment for mycorrhizal colonization.

“If the grower adds a lot of nutrients, plant-available phosphorus and nitrogen will decrease colonization rates by mycorrhizae,” she said. “It’s better to keep fertilizer inputs low or use organics. That will promote colonization by mycorrhizae.”

Dr. Lazcano noted that tillage also affects colonization rates of mycorrhizae. “Tillage obviously disrupts the soil and breaks the hyphae, which are the cells of the fungi, so it reduces colonization rates.

“Using cover crops, keeping living plants in the soil also helps that mycorrhizal population stay alive and active,” she continued. “So, in general, the management that is recommended to increase soil health will also help with improving colonization rates for mycorrhizae.”

 

What Should Growers Know?

A general misconception about mycorrhizal fungi is that simply inoculating a field with a product to boost mycorrhizal presence in the soil will automatically provide benefits. In reality, there are multiple aspects of the soil web that must work together for any benefit to be reaped from this fungus.

John Andreas of Soil and Crop Inc. said that good foundational nutrition, organic matter, minerals and accessibility to these is the best thing a grower can do to stimulate healthy mycorrhizal growth.

“Some people fall into the trap that all I have to do is put that [mycorrhizae] out and everything is going to be amazingly different, you know, ‘silver bullet’ mentality, and that’s just not the case,” Andreas said.

“It’s a powerful tool, but not standing on its own two legs. It’s just kind of a cornerstone product.”

CCA and SSp. Rich Kreps said that mycorrhizal fungi are regional, and the location of a soil and its available nutrients need to be considered when applying a mycorrhizal product. “Whatever is in your field is not the same as in Sequoia Park. If you live in Madera, it’s not the same as what you’ll find in McFarland.

“Mycorrhizae is definitely species-specific to a specific area in most parts,” he continued. “So, what you’ve got to do is you’ve got to increase your soil health to let the mycorrhizae do what it’s supposed to do. By increasing other forms of soil microbiota, you’re going to increase the propagation of the native mycorrhizae in your soil.”

Sterile soils lack of microbiota, which consist of organisms such as bacteria, archaea, protists, fungi and viruses, will not be able to propagate mycorrhizae well. To get an idea of what a given soil’s biology looks like, Kreps recommends conducting a soil respiration test, where soil is incubated at 68 degrees C with a moisture content of 72% for 24 hours.

“The offcasting of CO2 that comes out of that is going to be indicative of what your [soil] biology looks like,” he said. “If your soil is sterile, you’re not going to get much CO2 produced off of that ground.

“Increasing soil organic matter is going to greatly enhance the ability for soil biology then to flourish.”

Kreps warned that an anaerobic soil environment can be a major detriment to soil biology, including mycorrhizae. “You don’t want to go anaerobic for way too long,” he said. “That always has detriments; it may encourage detrimental diseases like pythium, phytophthora and fusarium. That’s never beneficial.”

Humic Acid Beyond the Marketing: Origins, Research and Effective Application

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Almost every fertilizer retailer carries humic acid. It is sold as a soil conditioner and fertilizer additive in hundreds of commercial products, and the total market value is expected to surpass $1 billion annually by 2024 (Pulidindi and Pandey 2017). Retailers claim that their products improve many aspects of soil health, yet researchers continue debating humic substances’ chemical structure and influence on soil chemistry and biology. University research, manufacturer trials and grower demos show yield and growth improvements after humic acid applications, but results are inconsistent and leave farmers wondering if they should skip the amendments altogether. Understanding how humic acids work will help agronomists determine when they have the highest potential to significantly improve crop quality or yield.

Humic acid products vary in source, manufacturing method and concentration, but they share common chemical characteristics and promote plant growth in similar ways. The amendments mimic some of the beneficial properties provided by soil organic matter. Manufacturers extract humics from leonardite, lignite, peat or other sources using processes similar to those researchers use to isolate humic substances in soil samples. Leonardite and lignite are ancient organic matter deposits that mineralized into rock formations over millions of years. Humic and fulvic acids derived from rock or peat approximate stable organic matter formed in biologically healthy soils.

Soil scientists study organic matter by classifying its components and exploring how each part influences the system. Researchers describe organic matter in several ways, but one useful model classifies it into four distinct categories: living organisms, fresh residue, actively decaying organic matter and stabilized organic matter. Together, the active and stable organic matter fractions comprise “humus”, the dark brown or black sticky substance characteristic of the most fertile soils.

Actively decaying organic matter includes familiar organic molecules such as carbohydrates, amino acids, proteins, fatty acids, microbial metabolites and cellular structures. The active fraction supplies energy and nutrients to support continued microbial growth and nutrient cycling. Microbial exudates such as globulin support soil aggregation and structure.

Humic acid products vary in source, manufacturing method and concentration, but they share common chemical characteristics and promote plant growth in similar ways (courtesy Stevenson 1982.)

 

Humic Substances

The stabilized organic matter fraction includes complex carbon compounds called “humic substances” that resist microbial decomposition. Humic substances’ molecular structures remain elusive, but we know that they are very reactive and form colloidal structures with minerals and clay particles. Scientists divide humic substances into three subcategories based on solubility in acid or alkaline solution. Humin is insoluble in acid and base, humic acid dissolves in alkaline solution but precipitates at low pH, and fulvic acid is soluble in both acidic and basic solutions. Humic and fulvic acids originate in soil, but they are extracted and defined by procedures that likely alter their form and characteristics. Laboratory extractions are the best method scientists have to differentiate humic components and study individual effects on nutrients, microbes and plants.

Research shows that humic substances provide much of the enhanced nutrient availability, water holding capacity and aggregate stability observed in soils with high organic matter. Ideally, most loamy soils should contain between 3% to 5% organic matter, but heavily farmed land often contain less than 1%. Though organic matter represents a small fraction of total soil weight, it has a disproportionately large impact on soil properties. Dropping from 4% to 1% organic matter represents a severe decline in health metrics leading to compaction, oxygen depletion, poor water and nutrient use efficiency, and more.

Applying humic and fulvic acids at common label rates won’t drastically improve soil structure or water holding capacity, but it may restore some of the other beneficial properties lost with declining organic matter. Humic and fulvic acid amendments benefit crops primarily by increasing nutrient uptake and preventing heavy metal toxicity. The products might also influence soil microbiology, but effects vary and remain difficult to predict in the field.

Humic substances increase nutrient availability by binding with essential nutrients and delivering them to roots in bioavailable form. Like clay particles, humic molecules have negatively charged sites that attract and hold positively charged cations like iron (Fe2+, Fe3+), zinc (Zn2+) and potassium (K+). While clay only has cation exchange capacity, humic substances can bind with anions as well. Nitrate (NO32-), borate (H2BO3-) and other negatively charged nutrients easily leach down below the root zone unless held in place by organic matter.

Agricultural crops’ micronutrient demand often exceeds the plant-available supply in soils with low organic matter and suboptimal pH. Micronutrient deficiencies reduce chlorophyll formation, stunt growth and weaken plant defense mechanisms. Iron, zinc, boron and other micronutrients dissolve in soil solution within a narrow pH and concentration range. Iron, in particular, has low solubility and precipitates easily in most agricultural soils. In natural ecosystems, plants obtain most of their iron from organic complexing agents like siderophores, organic acids and humic substances (Chen et al. 2004). In agriculture, growers use chelating agents such as EDTA and EDDHA to keep iron and other micronutrients in plant-available form.

Scientists divide humic substances into three subcategories based on solubility in acid or alkaline solution. Humin is insoluble in acid and base, humic acid dissolves in alkaline solution but precipitates at low pH, and fulvic acid is soluble in both acidic and basic solutions.

 

Complexing Agent

Humic and fulvic acid products provide an alternative complexing agent to organic farmers. Chen et al. 2001 showed higher chlorophyll concentration in ryegrass when iron and zinc fertilizers were applied with humic or fulvic acid versus mineral application alone. Humic and fulvic acids did not significantly increase chlorophyll production without the added micronutrients.

These results indicate that humic substances promote growth primarily through increasing nutrient availability, not through direct growth-stimulating effects. However, some researchers have observed increased biomass and yield even when humic or fulvic acids were added to a complete fertilizer program that already provided nutrients in plant-available form. Studies demonstrating enhanced crop growth beyond that attributed to optimal nutrient supply suggest that humic and fulvic acids work synergistically with fertilizers. Humic and fulvic acids appear to increase the plant’s capacity to take up nutrients, and with more essential elements, crops can support more growth and heavier fruit set. Fertilization and humic applications together increase crop production more than either one alone, especially in hydroponic systems, substrate, sand or soils with low organic matter.

Humic substances can also support crop health on soils with heavy metal contamination. The same mechanism that complexes and delivers micronutrients can also hold metals and other contaminants when their concentration in soil solution is too high. Humic and fulvic acids bind with contaminants shifting the equilibrium towards lower levels in solution. When applied at a high enough rate, humic acids can prevent crops from absorbing toxic levels of cadmium, zinc, manganese and other elements.

Whether applied via fertigation or foliar spray, humics can improve micronutrient uptake and enhance crop growth. Dose response studies show that humic and fulvic acid application rates optimize crop growth between 100 and 300 mg/L. Higher concentrations may decrease yield by interfering with other nutrient complexing agents in the soil or fertilizer solution. Use the percentage of humic or fulvic acid in the product to calculate the optimum application rate. Consult your advisor when applying products that contain other biostimulants in addition to humic substances. Label rates may reflect the combined effects of multiple active ingredients.

Humic and fulvic acids benefit crops thanks to their high reactivity and affinity for complexing nutrients. These amendments benefit crops most in arid regions where the soil has low organic matter and high pH. They can also improve crop growth in very sandy soils, substrate, and hydroponics. Applying humic and fulvic acids with iron, zinc, copper, and other nutrients helps farmers prevent nutrient deficiencies and improve overall crop health and vigor.

Eryn Wingate is an agronomist with  Tri-Tech Ag Products, Inc.

 

References

Essington, Michael E. Soil and Water Chemistry an Integrative Approach. CRC Press 2004. Print.
Lyons G, Genc Y. Commercial Humates in Agriculture: Real Substance or Smoke and Mirrors? Agronomy. 2016; 6(4):50. https://doi.org/10.3390/agronomy6040050
Magdoff, Fred and Weil, Ray R. Soil Organic Matter in Sustainable Agriculture. Chapter 4: Stimulatory Effects of Humic Substances on Plant Growth. CRC Press 2004. Print.
Pukalchik, Maria, et al. Outlining the Potential Role of Humic Products in Modifying Biological Properties of the Soil—A Review. Frontiers in Environmental Science. 2019; https://www.frontiersin.org/article/10.3389/fenvs.2019.00080
Pulidindi, K., and Pandey, H. (2017). Humic Acid Market Size By Application (Agriculture, Ecological Bioremediation, Horticulture, Dietary Supplements), Industry Analysis Report, Regional Outlook (U.S., Canada, Germany, UK, France, Spain, Italy, China, India, Japan, Australia, Indonesia, Malaysia, Brazil, Mexico, South Africa, GCC), Growth Potential, Price Trends, Competitive Market Share & Forecast, 2017–2024
Stevenson, F. J. 1982. Humus chemistry: genesis, composition, reactions. John Wiley & Sons, New York, NY. pp. 26–54.

Balancing Soil Fertility and Nutrient Management for Organic Farming

Organic farming has a long philosophical and historical focus on building soil fertility. Specifically, the USDA National Organic Program (NOP) requires organic farmers to “select and implement tillage and cultivation practices that maintain or improve the physical, chemical and biological condition of soil and minimize soil erosion,” “manage crop nutrients and soil fertility through rotations, cover crops and the application of plant and animal materials” and to “manage plant and animal materials to maintain or improve soil organic matter content in a manner that does not contribute to contamination of crops, soil or water by plant nutrients, pathogenic organisms, heavy metals or residues of prohibited substances.”

For agriculture in general there has been a shift away from a singular focus on building up the nutrient supplying capacity of soils and prevention of soil fertility exhaustion towards a broader focus on comprehensive nutrient management planning to deal with excess supplies of certain nutrients. Much of the nutrient management emphasis has been on nitrogen (N) and phosphorus (P), and the environmental and water quality concerns associated with both nutrients.

 

Balancing Mineral Nutrients

A fundamental principle of sustainable agriculture that applies to all farming systems is a need to balance mineral nutrient inputs and outputs over the long term. Development of a sustainable nutrient management plan for any given farming operation or land area requires quantitative information on imports and exports of mineral nutrients contained in composts, manures and fertilizers along with crop yields and sales records for agricultural products.

Published book values are often used to account for nutrient content of manures and composts, but because they can be highly variable, a lab analysis of the specific material is preferable. Major agricultural commodities exported from a farm may be from crops such as grains, forages, fruits, vegetables and fibers, or from animal products such as meat, milk or eggs. Nutrient leaching, runoff and erosion are also a kind of export or soil fertility loss growers should strive to minimize.

The mineral nutrient content of harvested agricultural products could be measured in each specific instance for comprehensive nutrient management planning, but at the present time and for practical purposes are usually based on reference book values. With respect to mineral content, it might be assumed that “corn is corn” or that “milk is milk”; however, these may be false assumptions since some research suggests local soil fertility conditions and production systems may influence the nutrient content.

Organic growers must keep certain types of production records for purposes of their annual review for inspection and organic certification. Likewise, organic growers must keep detailed records of imported compost or source materials used in making compost. They must also document use of approved organic fertilizers and application rates. These same production input and sales records can also be very useful for the purpose of nutrient management planning in organic farming operations.

A look at different rates of compost.

Given the limited reliability of reference values for purposes of nutrient management planning, keeping records of soil test results and tracking changes in values over a period of several years can be an alternative way to evaluate the sustainability of a nutrient management program. If soil fertility values over a period of several years are trending downward or upward beyond recommended optimum soil test levels, this can alert organic farmers to necessary adjustments in nutrient management.

The way a farm conducts operations related to production of crops and livestock can create its own challenges. For example, in some regions, large volumes of manure are produced by conventional concentrated animal feeding operations (CAFO). Such manures are sometimes made into compost and used on organic farms. Repeated use and application of CAFO-sourced manures or compost can result in accumulation of certain nutrients from manures beyond local soil/crop production demand.

The excess nutrient accumulation problem is not limited to organic farming operations. This also can happen on conventional farms that utilize manures without consideration of nutrient balance. This ecological problem stems in part from a geographical separation of grain and forage production and its export to animal feeding operations where manures accumulate beyond the nutrient needs of local soils.

To the extent that organic livestock farms are pasture-based and feed minimal amounts of imported organic feeds, these organic operations tend to avoid this nutrient imbalance problem. Products such as hay, where the whole aboveground biomass is harvested, tend to export the greatest amount of nutrients from a field. Unlike machine harvest, grazing the same field with cows to produce milk or meat recycles much of the nutrients in place and exports much less nutrients from the farmland. Farming systems that emphasize grazing also tend to be effective at building the soil N fertility and reduce the need to import off farm N fertility.

Stockpile of compost at the Ag Choice composting facility in Sussex County, New Jersey.

When organic dairies rely heavily on a mix of perennial legumes and grass forage, this minimizes the need to produce corn or other N-demanding grain crops. An organic dairy with a well-designed crop rotation can easily be managed to be self-sufficient with respect to N by recycling on-farm nutrient sources and by drawing upon the unlimited supply of N from the atmosphere. Other nutrients, such as P and K, can also be recycled on-farm. However, P and K may become deficient unless nutrient exports in the form of livestock products are balanced with imports.

Organic dairies are generally less focused on high milk volume per cow and more concerned about sustaining herd health, decreasing production cost by feeding pasture and forages in place on concentrates and internalizing farm nutrient cycling. Leguminous crops are an important feature of crop rotation on organic farms. Nutrient export from farms marketing forages through sales of milk, meat or eggs is only a small fraction of what would leave the farm gate by direct sales of the hay or grains by farms without livestock.

Organic feed, especially grains, tend to be expensive. Organic dairies are typically managed to supply as much of the livestock feed as possible and from greater reliance on forages. In contrast, in conventional agriculture, large numbers of animals are often raised in confinement and fed relatively inexpensive commodity grains that may be imported from a great distance beyond the local region.

The transition of some conventional farms to the organic system has created new markets or outlets for an overabundance of poultry and other manure types from CAFOs. Whenever crop rotations and cover crops fail to fully deliver the amount of N needed and because organic farming prohibits direct use of synthetic commercial N sources, organic growers of grains and vegetables often look towards manures and composts as a source of supplemental N.

The use of manures or compost made from conventional livestock operations as a N source (much of it originating as synthetic N fertilizers) in organic farming has sometimes been described as “repackaged” N when used in organic vegetable farming.

Manure composts must be used with consideration of nutrient balance in mind.

 

Nutrient Management Planning

Soil fertility recommendations provided by soil testing laboratories and nutrient management advisors are often prescriptive for simple chemical carriers of specific nutrients. Since some commercial fertilizer sources are classified as prohibited substances by the NOP, nutrient management can be a complex problem in certified organic farming.
The challenges and complexity of nutrient management planning are illustrated in an example of using a 5 ton/acre application of poultry manure as fertilizer (Table 1). Although organic farmers would not grow a monoculture of corn after corn, it is interesting to note how many years of grain harvest would be involved in utilization of each individual nutrient. For the major nutrients, about three to five harvests of corn for grain would utilize the applied NPK. In contrast, it would take more than 80 years of grain harvest to utilize the manganese or copper applied from that same poultry manure.

Table 1: Typical nutrient content of broiler litter manure (single application at rate of five tons/acre) and number of years of corn grain harvest to utilize applied nutrients.

When the whole aboveground biomass is harvested instead of grain or seed, nutrient removal typically occurs quicker. If, for example, a hay crop was grown and harvested after the poultry litter manure application, most the of the N and K would be utilized in less than two years instead of the three to five years for corn grain.

It should be noted that crop nutrient uptake and removal are two different parameters. This is illustrated with data for sweet corn presented in Tables 2 and 3. The values given in Table 2 show quantity of various nutrients taken up by the vegetative biomass of a sweet corn crop. Although the nutrients are taken up from the soil by the crop, sweet corn biomass is generally chopped and left behind as residue on the field. Consequently, the nutrients are recycled in place on the field.

Table 2: Nutrient uptake in sweet corn biomass without the marketable ears. This data set is based on a plant population of 23,231 plants per acre.
Table 3: Nutrient uptake and removal by sweet corn harvest. This data set is based off of a yield of 18,400 marketable ears with an average ear size of 0.82 pounds per ear.

The values given in Table 3, however, show the quantity of various nutrients taken up by the marketable sweet corn ears that are harvested. Because the ears are going to market, the nutrients contained within are removed and exported from the field.

Thus, how a crop is harvested or taken from a field matters in terms of nutrient management. Imagine, for example, if a corn crop was harvested as silage or feed rather than just for ears or grain. Although not normally done in the case of sweet corn, in such case the values shown in Tables 2 and 3 would be combined to calculate nutrient removal.
Beyond sweet corn, nutrient removal amounts for a wide range of harvested crops can be found by web searching for extension publications.

Nutrient management planning has typically been primarily focused on managing N, P, and K, but with increasing attention focus on sustainability, micronutrients could also become a concern. In the case of micronutrient fertilization, organic and conventional agriculture have much in common. Many of the same micronutrient fertilizer sources are permitted in organic as in conventional agriculture. The main stipulation for organic systems is that plant or soil diagnostics is a requirement to document a need for a particular micronutrient fertilizer application before it may be used. However, micronutrient inputs that come from manures and composts are generally not given the same attention as specific micronutrient fertilizer products.

Soil fertility management in organic agriculture is not a separate activity but rather is an integral part of the whole-farm system. Thus, nutrient management advisors are challenged to balance nutrient inputs and ratios from complex source materials of variable composition and variable rates of availability for crop and livestock nutrition. The type of bedding material used for livestock greatly influences the composition of animal manures and the carbon to nutrient ratio.

Bedding materials often contain high levels of carbon relative to N or P. Wood shavings or straw bedding materials typically have C:N ratios well above 30. A wide carbon to nutrient ratio can temporarily reduce availability of N or P in soil. Decomposition of these materials in soil means that microorganisms will seek to satisfy their own need for N in competition with crops.

Composting of the manure is one way to work around this problem. Compost made according to the organic program standards for turnings and temperatures is designed to protect against foodborne pathogens when used as a soil fertility amendment in vegetable production.

However, compost should not be used as a primary N source for vegetable production. Only about 10% of the N contained in compost might be available to a crop in the first growing season. Organic growers who have repeatedly used heavy application rates of compost often find that soil test P levels soon become elevated beyond the optimum range. Excessive soil fertility P levels draw the attention and environmental concern of nutrient management planners.

An accounting for a balanced flow of nutrients onto and from an organic farm operation is not a simple process. But it is manageable with knowledge about the composition and flow of soil fertility inputs.

Equally important is the type of cropping system, including the types of crops grown, how they are harvested, the long-term crop rotation, the inclusion of cover crops, livestock integration and time.

As previously mentioned, regular soil sampling and record-keeping can be used to track soil fertility trends in farm fields. Organic growers should be striving for improving soil fertility and soil health while at the same time sustaining nutrients levels in an optimum range for crop production.

Dr. Joseph R. Heckman, Ph.D., is a Soil Fertility Extension Specialist at Rutgers University.

Organic growers who have repeatedly used heavy application rates of compost often find that soil test P levels soon become elevated beyond the optimum range.

Improving Understanding of Herbicide Drift Symptoms on Hemp

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UCCE Farm Advisor for Sutter, Yuba, and Colusa counties Sarah Light and UCCE Weed Specialist Brad Hanson simulated the drift symptoms in the 2019 project, photographed the affected plants and published their work in a May 2021 UC ANR publication.

Light said when asked why the pair pursued the project. “It wasn’t a response to something that happened. It was just a way to provide a tool so if drift does happen, growers know what it looks like, and to make sure there aren’t any unfounded accusations against our existing growers who are managing their commodities.

“We have a new crop in the landscape,” she added. “It is high value. We have our existing growers who are managing their crops, and we want to be able to protect everybody from any issues.”

Hemp production was legalized in the U.S. under the 2018 Farm Bill. According to CDFA, there are now more than 550 registered hemp growers in the state and more than 50,000 acres registered for hemp production. The crop has many uses, including as a food product, in textiles and biofuels, but it is the medicinal properties of hemp-derived cannabidiol (CBD) that is the most sought after.

Scott Bowden, deputy ag commissioner for Sutter County, who is in charge of pesticide use enforcement, said that to date, there hasn’t been a complaint of herbicide drift on hemp in the county. But he is concerned, nonetheless.

“I’ve been waiting since 2019 for drift incidents,” he said, “but we haven’t gotten any complaints yet. Which isn’t to say that it hasn’t happened; we just haven’t had any complaints.”

Bowden believes one reason why involves the timing of herbicide use in rice, a dominant crop in the county, in relation to when hemp is transplanted. “They plant the crop [hemp] after July, after the rice herbicides have been used,” Bowden said. “That has really helped keep drift issues down.

“A big reason we have not had any drift complaints is because we have professionally trained and licensed applicators who spray for a living, and no one wants to drift onto any other crops,” he added.

 

Proper Diagnosis Critical

Typically, when drift is misdiagnosed, an abiotic issue is the culprit, according to Light. Biological organisms, such as insects and diseases, move in a nonlinear pattern and typically are not associated with drift, she said.

“Certainly, if you had one hemp plant damaged in the middle of your field, that is never going to be a drift issue,” Light said. “Drift issues would likely be confused with a nonbiological issue, like say soil compaction on a field edge.

“Diagnostics is really a complex, very nuanced thing,” Light added. “And yet proper diagnostics is critical for any pest management program.”

In the demonstration project, Light and Hanson transplanted hemp plants on July 25. Three weeks later, they applied low-rate treatments of several herbicides to the foliage. They then photographed the plants over a two-week period.

“In a more typical drift situation, symptoms may be less dramatic than those documented in this publication,” the researchers wrote, “while direct applications of full rates may cause even more severe symptoms (including plant death).”

The researchers applied 19 commonly used herbicides, including glyphosate, paraquat, glufosinate, saflufenacil, carfentrazone, oxyfluorfen and propanil. In the document, they ran two dozen pictures of hemp affected by herbicide drift at different durations after application.

The publication also includes descriptions of the damage and explanations for what happened within the plant to cause the damage. Paraquat, for example, the researchers wrote, is a postemergence contact herbicide that disrupts energy flow during photosynthesis and can cause injury within hours after application. Symptoms of paraquat damage include chlorosis, a yellowing of leaf tissue due to low chlorophyll, or necrotic (dead) spots associated with individual spray droplets, the researchers wrote.

In general, the symptoms documented in the project are similar to herbicide symptoms in other crops, according to an email response from Hanson.

“There was nothing unexpected observed,” Hanson said in answering whether researchers encountered any surprises. “Herbicide symptoms are pretty consistent across crops and the trends toward recovery (or not) were consistent with what you’d expect from other crops.”

The researchers did not carry the plants to maturity in the project.

 

Many Forms of Drift

Pesticide drift can take several forms, according to the California Department of Pesticide Regulation (DPR), including appearing as a cloud of dust, or it can be invisible and odorless. Drift also isn’t limited to the period during or immediately after an application, according to DPR.

“Days or even weeks after application, pesticides can evaporate (volatize) into a gas,” DPR writes in a document on drift.

While some drift, particularly small amounts, is unavoidable, DPR notes that drift can be minimized by taking steps, such as ensuring equipment and application techniques minimize drift and applying pesticides only when conditions warrant, such as when wind speeds are low.

DPR also advises applicators to follow label directions when applying products as an additional means to avoid issues with drift.

While as of mid-June, Bowden said he had yet to field a complaint about herbicide drift onto hemp in Sutter County, he was concerned that issues could occur this summer. A county ordinance has now banned hemp producers from producing the crop within a certain distance of population centers, an ordinance that is expected to push hemp producers further into agricultural production areas, making drift issues more likely to occur.

He is encouraging producers to open lines of communication in hopes of avoiding issues with drift. “We are trying to encourage grower-to-grower contact,” he said. “That way, they can let their neighbor know when they are going to spray, and a hemp grower can do things like cover intake fans in cases where hemp is grown in a greenhouse.

“That is the best situation,” he said. “Whether it is drift between a rice grower and a hemp grower or a residential homeowner and a hemp grower, if you can open up those lines of communication, that is a much easier way to get things done than going through our office.”

The project report can be viewed at anrcatalog.ucanr.edu, publication No. 8689.

Anaerobic Soil Disinfestation as an Organic Systems-Based Approach

Anaerobic soil disinfestation (ASD) is a series of biological and chemical processes that occur when soil is made anaerobic with irrigation after a carbon amendment has been incorporated. But, like all biological processes, environmental conditions affect if and how rapidly the processes occur, which means that ASD does not work in all situations. Soil temperature, moisture, type and amount of carbon added all impact ASD effectiveness. Furthermore, the conditions needed for ASD to be effective depend on the specific pathogen(s) you are trying to control. So, while there are general principles to follow, specific ASD management guidelines need to be worked out for each region and pathogen. Here, we provide a summary of current knowledge for regions across the U.S.

 

ASD in California

In 2003-04, ASD was shown to be successful at suppressing Verticillium wilt in strawberries at the UCSC Center for Agroecology and Sustainable Food Systems. By 2010, a bed-treatment ASD system using 6 to 9 ton/ac rice bran as a carbon source was developed for control of V. dahliae (see Part 1 of this article in the June/July 2021 issue for details of typical steps for ASD implementation.) Work has since expanded to address control of other strawberry pathogens, and field trials for a variety of tree crop nurseries show promising results.

Commercial application of ASD began in 2011 and has been increasing. In 2019, 1,700 acres of mainly organic strawberries and cane berries were treated with ASD. Some organic strawberry nurseries also use a broadcast flat ground version of ASD. Rice bran has been the most popular carbon source used, but other options include wheat bran and waste materials like grape pomace, coffee grounds and wheat Midds (wheat millfeed).

Farmers in a focus group assessing production of organic okra using ASD in Marion County, Fla. (photo by E. Rosskopf.)

 

Benefits of ASD in California:

  • ASD suppresses Verticillium wilt in strawberries with our region’s late summer-fall soil temperatures (65 to 75 degrees F).
  • Six to nine tons/acre of rice bran provides 70 to 100 lb/acre of slow-release plant-available nitrogen in the first six months, and a season-long supply of phosphorus, thereby reducing or eliminating the need for pre-plant fertilizers. Other materials with lower nitrogen content may require pre-plant fertilizer.
  • Rice bran-based ASD provides fruit yields equivalent to fumigation, but see below for exceptions.
  • Cover crop or crop residues can partially substitute for rice bran, reducing the cost of ASD, while still providing effective control.
  • Addition of rice bran reduces the bulk density of clay soils and improves water infiltration and salt leaching.
View of a cover crop trial conducted in 2019 (photo by F. Di Gioia.)

 

Limitations of ASD in California:

  • High soil temperatures (>86 degrees F) are required for ASD to suppress Fusarium wilt of strawberries. If ASD is applied to a Fusarium-infested field in the fall, it can increase disease severity because at lower temperatures, Fusarium feeds on the rice bran before the anaerobic and beneficial bacteria are able to.
  • Summer ASD using clear mulch to raise soil temperature and strong anaerobic conditions are needed to control Fusarium wilt.
  • Temperature and anaerobic thresholds for ASD to suppress charcoal rot (Macrophomina phaseolina) are not established, but are likely higher than for Verticillium.
  • The cost of rice bran is increasing ($350 to $380/ton in 2021), but less expensive materials look promising.
  • ASD is not a silver bullet and should be used in combination with other tactics such as crop rotation and use of resistant cultivars.
Sudan grass and rice bran (in sandbags) as carbon sources for ASD in an organic field at the Center for Agroecology and Sustainable Food Systems, UC Santa Cruz (photo by J. Muramoto.)

 

ASD in Florida

Considerable work has been done on ASD in Florida for vegetables and cut flowers. Early research established that ASD using clear plastic mulch effectively controlled Fusarium oxysporum, root-knot nematodes, Phytopathora capsici and grass weeds in pepper/eggplant double crops. Using clear mulch is an issue since it must be painted or replaced for the crop cycle as temperatures under clear mulch are too high. Subsequent work in tomato, however, showed that opaque totally impermeable film (TIF) could be successfully used for ASD. Research is underway on ASD for strawberry with promising results.

Several commercial organic producers are using ASD for growing organic tomatoes, mixed specialty vegetables and cucumbers. Originally, sugarcane molasses was used as the carbon source for ASD, but cover crops, mustard seed meal, wheat and rice bran, corn gluten, citrus and beet molasses, and composted algae have all been investigated. So far, the combination of pelleted poultry litter and molasses is the most effective approach.

 

Benefits of ASD in Florida

  • ASD consistently controls numerous soilborne plant pathogens, including root-knot nematode, and reduces weed pressure.
  • For farmers who already use organic amendments, it fits easily into their production systems.
  • ASD improves plant nutrition, results in higher fruit yields and maintains or improves quality.
  • Compared to fumigation for tomatoes, ASD provided greater returns despite higher application costs.

Limitations of ASD in Florida

  • ASD requires a large quantity of organic amendments. For growers who have not used organic amendments, the logistics of applying material to large acreage is a barrier to widespread adoption.
  • Some pathogens, like Macrophomina, may require use of clear mulch during ASD to raise soil temperatures. Current research is addressing this question and the quantity of inputs needed for ASD in strawberry.
  • A limitation for some is the use of plastic mulch at all. Different types of coverings that may be more sustainable are being investigated.
ASD experiment conducted using buckwheat and sugarcane molasses as carbon sources in the summer of 2019 using a movable high tunnel structure (photo by F. Di Gioia.)

 

Southeastern U.S.

Research on ASD has focused on warm-season vegetables and cut flowers (TN), and recently strawberries (NC, TN). For warm-season vegetables, ASD is used to control southern blight (Sclerotium rolfsii) and Fusarium wilt (F. oxysporum) and is applied in early/mid-spring for open field production, and at variable times for protected culture. Strawberries are planted in the fall and removed in mid-June, providing an ideal time with high summer temperatures for ASD just before planting. The major focus for strawberries is control of black root rot (BRR) caused by a complex of Rhizoctonia and Pythium species. BRR can suppress yields by 20% to 40%.

Many agricultural by-products and plant residues can be used with ASD. One good option is a mixture of dry molasses, soybean hulls and wheat bran. This mix provides sufficient decomposable organic compounds to drive fermentation, a moderate C:N ratio that simplifies crop fertility management, is widely available and improves physical properties of high-clay soils typical in the region. Generally, by-products that have small particle sizes, contain decomposable organic compounds and are locally available for low cost will work for ASD. Crop and cover crop residues also work, but particle size and decomposability vary depending on mowing/chopping equipment, crop species and growth stage. On-farm studies have been conducted with organic and conventional growers, but commercial adoption is limited to organic fresh-market high tunnel tomato production.

 

Benefits of ASD in the Southeast

  • ASD suppresses various soilborne pathogens and enhances vegetable yields.
  • Beneficial biocontrol and biostimulant soil fungi are enhanced post-ASD, including populations of Trichoderma spp. and colonization of crop roots by mycorrhizal fungi.
  • ASD suppresses BRR and improves strawberry yield, performing similarly to fumigation.
  • There is good evidence of winter annual weed suppression by ASD.

 

Limitations of ASD in the Southeast

  • For open-field vegetables, ASD done in early/mid-spring will not control Fusarium because soil temperatures are too low, but in high tunnels or greenhouse systems, there are options for ASD when soil temperatures are higher.
  • ASD is knowledge and management intensive. Variables to manage include type and amount of carbon to add, methods of incorporation and timing of application.
  • Crop fertility management must be adjusted depending on the nitrogen content of the carbon source used (detailed plant management information is available on the NC State strawberry grower portal.)
  • Planting date is critical for strawberries. Planting two weeks late can reduce yields by 50%. If excessive rain events occur, there may not be time to do ASD prior to planting.
    Cost of carbon inputs, transportation, labor and management can be higher than other less intensive systems.
Example of on-farm ASD application in a Pennsylvania high tunnel: a) application of chicken manure; b) preparation of feed-grade sugarcane molasses mixed with irrigation water (1:1 v:v) and c) application on top of the bed; d) molasses and chicken manure being incorporated in the soil; e) preparation of raised beds with TIF and two drip lines per bed; and f) installation of ORP sensors to monitor soil redox potential during the ASD treatment (photo by F. Di Gioia.)

Northeastern U.S.

Research on ASD began in 2019 in Pennsylvania for controlling northern root-knot nematodes (Meloidogyne hapla), tomato white mold (Sclerotinia sclerotiorum), Verticillium and Fusarium wilt, especially in high tunnel vegetable systems where diseases are more severe than in open fields. Questions being addressed are how to integrate ASD into current production systems, what the best times for application are and what locally available carbon sources are effective for ASD.

ASD is being tested by high tunnel fresh-market tomato growers looking to improve soil health and manage soilborne pathogens. However, there is limited information available on how to optimize ASD for these systems. Recent work found that a buckwheat cover crop could be effective either as the sole carbon source for ASD or in combination with molasses. Other work is testing fresh vegetable residues, brewer’s spent grain, wheat Midds, spent mushroom compost and grape pomace as carbon sources, with wheat Midds showing particular promise.

 

Benefits of ASD in the Northeast

  • ASD addresses emerging soilborne pathogens, enhances soil health and provides nutrients to the following crop.
  • It can be integrated with other biological strategies such as cover crops and grafted plants.
  • Limitations of ASD in the Northeast
  • The main limitation is the short window of time available for application of ASD in typical crop rotations. Based on soil temperatures, the best times to apply ASD are late summer to early fall after an early tomato crop. However, ASD cannot be done immediately before establishing the tomato crop due to low soil temperatures (<60 degrees F) over the winter.

For more specific information on how to manage ASD in your area, please check out the resources below, or contact the authors of this article.

 

Additional Resources

California:
The Shennan Lab website
https://shennanlab.sites.ucsc.edu/home/page-builder/alternatives-to-soil-fumigation/
ASD YouTube video
https://youtu.be/uxHs2eM7YzY
UCCE Ventura County Strawberry website
http://ceventura.ucanr.edu/Com_Ag/Strawberry/

Florida:
UF IFAS ASD webpage
https://floridafoodandag.com/new-home/anaerobic-soil-disinfestation-asd

Southeastern U.S.:
Introduction to ASD as a Fumigant Alternative https://extension.tennessee.edu/publications/Documents/SP765-A.pdf
Implementing ASD in Tennessee
https://extension.tennessee.edu/publications/documents/sp765-b.pdf

Northeastern U.S.:
ASD in High Tunnel System YouTube video Part 1
https://youtu.be/dx8xU1CDxKc
YouTube video Part 2
https://youtu.be/pg4POlMAHTo
The Sustainable Flowers Podcast on ASD
https://sustainableflowerspodcast.libsyn.com/anaerobic-soil-disinfestation-working-with-soil-organisms-to-control-pests-and-disease-in-hoophouses

The Crop Consultant Conference Returns as In-Person Event Over Two Days

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Progressive Crop Consultant Magazine’s popular two-day Crop Consultant Conference will return this year as a live conference and trade show, featuring seminars worth 10 hours of CCA and 8 hours of DPR continuing education credits, a live trade show, and the presentation of Western Region CCA Association’s popular CCA of the Year Award and honorariums and scholarships. The Crop Consultant Conference will be held on Sept. 16 and 17 at the Visalia Convention Center.

The Crop Consultant Conference has become a premier event held in the San Joaquin Valley each September for Pest Control Advisors and Certified Crop Advisers. Co-hosted by JCS Marketing, the publisher of Progressive Crop Consultant Magazine, and Western Region Certified Crop Advisers Association, the event brings industry experts and suppliers, researchers and crop consultants together for two days of education, networking and entertainment.

“We are excited to be back to doing our events in person, and expect another sell-out event for crop consultants in the Western United States,” said JCS Marketing Publisher and CEO Jason Scott. “Agriculture is a relationship-driven business and there is no substitute for live events.”

Topics for the two days of seminars include: Various seminars on managing pests and diseases in high-value specialty crops, tank mix safety and regulations, fertilizer management, soil health, new technology, new varieties and rootstocks and their impact on tree nut pest management.

The conference will conclude with two one-hour panels offering hard-to-get CCA credits and moderated by Western Region CCA related to nitrogen monitoring, use, application and management as well as the various regulatory requirements around irrigated nitrogen management.

Registration fees for the two-day event are $150, or less than $15 per CE unit. Pre-registration is required and can be done at progressivecrop.com/conference.

Click Here to Register Now

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