Soil, Cover Crops, & Systems

Resources & Research  |  From the Organic Broadcaster

Soils and Systems Fact Sheets:

1. How to Choose Cover Crops
2. Managing Soil Fertility and Organic Matter



Ask an Organic Specialist: Soils Answers

Can I use my non-organic neighbor’s manure on my organic field?

Answer by Organic Specialist Harriet Behar:

You are allowed to use manure from non-organic livestock on your organic fields. When sourcing manure from another farmer, regardless of their organic status, your certifier will require documentation that the manure is free from certain materials detailed here. Most have forms to help you get the information you need.

Bedding: If the manure includes wood-based bedding, it cannot contain prohibited synthetics, like treated wood shavings or glues/paints/heavy metal-based inks. On the other hand, any conventionally raised crop is allowed as bedding in manure that can then be spread on organic land.

Piles and Lagoons: A manure pile or lagoon cannot have prohibited synthetic items used in or on the manure. For example, no non-approved fly sprays or herbicides may be used on manure piles, or non-approved synthetics put in manure lagoons to control odor. A natural lactobacillus bacterium is allowed as a manure lagoon additive, as long as it does not contain non-approved synthetics. Manure that has been piled outside or in a barn for 10 years with no turning and/or no documentation that it reached the high temperatures required for compost (see below) is still considered raw manure, and can only be used according to the manure restrictions on human consumed crops.

Human-consumed crops: If you are growing crops for human consumption, and the manure is not composted or processed, the manure must be incorporated either 120 days before harvest of the crops where the crop has contact with soil (either growing in or near the soil, such as beets, lettuce, or potatoes), or wait 90 days before harvest where the crop does not have contact with soil (corn, wheat, or trellised tomatoes). Plastic mulch is not considered a barrier and does not change the wait time requirements. The National Organic Program does not have a list of crops to determine if they are considered in direct contact with the soil, so check with your certifier if you have questions about a specific crop.

Composted manure: Composted manure can be used up until day of harvest with no restriction. The NOP has a specific definition of compost. The combined plant and animal materials must have an initial C:N ratio between 25:1 and 40:1. In-vessel or static aerated pile systems must stay between 131 °F and 170 °F for 3 days. Windrow systems must stay between 131 °F and 170 °F for 15 days. During that time, the materials must be turned at least five times. If you are composting only vegetative matter, without any animal by-products, then there is no requirement to track the compost reaching a specific temperature. Non-animal product compost can be spread this on your organic crops at any time.

Using manure: Be aware that raw manure that has not reached the high temperatures of composting or processing will contain viable weed seeds. You will be adding more, and possibly different, weed seeds to your fields. It is a good idea to obtain an analysis of the manure you are using so you can better manage for the nutrients it provides.

Can I use compost from my county’s composting program on my organic farm?

Anwer by Organic Specialist Joe Pedretti: Municipal compost is becoming more common as communities switch to composting yard and kitchen waste instead of sending it to a landfill. The National Organic Standards separates compost in two groups: one that might contain fecal matter from animals or humans, and one that does not. Within each group, the compost must meet specific criteria to qualify for use on organic farms.

Compost that might contain manure must meet the composition, temperature and turning specifications in the National Organic Standards:

(i) Established an initial C:N ratio of between 25:1 and 40:1; and

(ii) Maintained a temperature of between 131 °F and 170 °F for 3 days using an in-vessel or static aerated pile system; or

(iii) Maintained a temperature of between 131 °F and 170 °F for 15 days using a windrow composting system, during which period, the materials must be turned a minimum of 5 times.

The county/city must provide the documentation to show these standards were met before you can use a material as compost. If they cannot prove they have met these standards, it may be possible to still use it, but it will not be considered compost, it will be considered raw manure, and will have different handling requirements:

1) Raw animal manure, which must be composted unless it is:

(i) Applied to land used for a crop not intended for human consumption;

(ii) Incorporated into the soil not less than 120 days prior to the harvest of a product whose edible portion has direct contact with the soil surface or soil particles; or

(iii) Incorporated into the soil not less than 90 days prior to the harvest of a product whose edible portion does not have direct contact with the soil surface or soil particles;

Composted and un-composted plant materials without manure have no application restrictions, but the composting center must verify that the compost contains only 100% plant materials. If there is a possibility that it contains pet waste (animal manure) then it must be handled as raw manure.

Whether or not it contains animal manure, you still must make sure compost contains no prohibited materials:

•Recycled building materials/lumber (due to paints, varnishes and glues)
•Human waste
•Plastics and other un-compostable synthetics

Check with the composting facility to see if they have the necessary documentation. If other organic farmers have been using their product, it is quite likely they have this paperwork on hand. Also check with your certification agency, which can do a product review if it has not already reviewed this compost for other farmers. Ultimately, your certifier makes the final call on whether a product is allowed or not. All new inputs should always be verified and added to your crop input list before use.

My neighbor is certified organic by a different agency than I am. He uses a blended fertilizer product on his certified organic land. Can I use the same fertilizer on my organic land?

Answer by Organic Specialist Harriet Behar: 

Since the materials you use are part of your specific organic system plan, you must verify with your own agency if it has reviewed and approved this product before you apply it to organic land or crops.

This is true even for products that are allowed without restrictions, like pelleted chicken manure. Other products have restrictions. You need documentation of a deficiency in order to use fertilizers with synthetic micronutrients. Some products are allowed for some uses and prohibited for others. For example, a pesticide may be approved for use on crops but prohibited to spray on livestock to control flies.

Some organizations are accredited to review organic inputs, like OMRI, WSDA, and CDFA. Input manufacturers pay to be on their public lists. Certification agencies often accept any products on these lists, but you still must inform your agency if you choose to add one to your Organic System Plan’s list of inputs used on your organic land or crops. You can ask your certifier what the agency’s policy is on OMRI, WSDA, and CDFA-listed brand name products to help you when deciding which products to purchase.

Since product formulations may change periodically, certifiers will want you to update each year what inputs you are purchasing and using, so they can check that they have current ingredient information to verify the product is still in compliance with the organic regulations.

It can be frustrating to know that some certifiers accept a product and others may not. This can happen when a new product comes on the market, like paper pots, that land in gray areas of the National Organic Standards. The National Organic Program and the National Organic Standards Board work together to offer guidance when disputes occur. Certifiers also communicate with each other to understand differences of opinion on disputed materials and try to come to an agreement. No one in the organic industry wants farmers certifier shopping based on what they allow, but it can be a slow process for all parties to get on the same page.



Resources & Research:

Land Stewardship Project (LSP) has published a 50-page “pocket” guide to help farmers be “soil smart” in a changing climate. The guide includes everything from an explanation of soil smart farming practices to crop and livestock integration. There are also profiles of farmers who are leading the way on building soil health.

Practical Farmers of Iowa provides a report summarizing the research results conducted by three farmer-cooperators on spring-seeded brassica cover crops. The cooperators hand-seeded six different brassica cover crops into soybean stubble in small plots. Before terminating the spring cover crops, cooperators evaluated each species for the amount of
groundcover provided.

The Organic Farming Research Foundation (OFRF) provides a series of educational guides to help organic farmers and ranchers enhance soil health and overall resilience of their operations. Topics include soil health and organic farming, building organic matter, weed management, conservation tillage, cover crops, plant breeding, water management, and nutrient management. The guides come as a set, and are available for free download on the OFRF website.

Easily compare 58 crop species with a new cover crop chart from the Northern Great Plains Research Laboratory. The 67-page document includes the chart showing growth cycles, plant architecture, and relative water use, plus additional details for each species such as seeding depth, pollination characteristics, and forage quality. Primary sources of information include the Midwest Cover Crops Council, USDA-SARE, and USDA-NRCS PLANTS Database. For recommendations on choosing cover crops based on the desired outcomes, see the “How to Choose Cover Crops” MOSES factsheet available at the top of this page.

A team of cover crop experts from the Midwest Cover Crop Council has created a web-based system of Cover Crop Selector Tools to help farmers select the best cover crops for their area. The online tools walk farmers through the process of choosing their region, soil drainage class and goals such as finding soil builders, nitrogen sources, weed fighters and forage harvest values. The tools deliver recommendations of various cover crop species and their optimal planting date windows based on 30-year average frost dates in the user’s county.

SARE Outreach announces a new planning resource for farmers seeking sound, science-based guidelines for managing crop rotations in organic farming. Free to download or $24 to get a printed copy.

The USDA-NRCS has a new series of short videos highlighting ways to improve soil health while benefiting the environment and lowering production costs. The series includes interviews with some of the nation’s leading experts in soil biology, agronomy, entomology, and soil ecology.

A guide to the Conservation Reserve Program from the National Sustainable Agriculture Coalition (NSAC).

This checklist from the Natural Resources Conservation Service (NRCS) can help farmers increase crop production and profitability by managing for soil health. The 2-page PDF shows the benefits of various types of soil health management systems and covers the four basic principles for improving soil health:
1. Keep the soil covered as much as possible.
2. Disturb the soil as little as possible.
3. Keep plants growing throughout the year to feed the soil.
4. Diversify as much as possible using crop rotation and cover crops.

A long-term southern Wisconsin cropping systems study shows that soils under managed grazing have a number of positive characteristics compared to soils under other cropping systems. The Wisconsin Integrated Cropping Systems Trial (WICST) provided data on three cash grain cropping systems and three forage systems. The study found some interesting differences between the systems in terms of erosion potential, earthworm counts, water stable aggregates, soil carbon, and the Soil Quality Index.

The pocket-sized guide from Purdue University and the Midwest Cover Crops Council is designed to help farmers choose, grow and use appropriate cover crops in their farming operations. The updated edition features seven new topics, including suggested cover crops for common rotations, seeding rates, and research on cover crops’ impacts on cash crop yields. The 166-page resource is $5.

The National Wildlife Federation has released a report from a June 2012 meeting that brought together 36 of the leading experts in cover crops in the Midwest and Great Plains. These farmers, scientists, extension specialists, and policy experts met for two days to discuss what they saw as the biggest barriers to expanded cover crop adoption. The “Roadmap” they developed for addressing these barriers is the first step toward achieving the goal of 100 million acres of cover crops by 2025.

Provides soil data and information produced by the National Cooperative Soil Survey. It is operated by the USDA Natural Resources Conservation Service (NRCS) and provides access to the largest natural resource information system in the world. NRCS has soil maps and data available online for more than 95 percent of the nation’s counties and anticipates having 100 percent in the near future. The site is updated and maintained online as the single authoritative source of soil survey information.

The Natural Resources Conservation Service (NRCS) offers a series of fact sheets on soil management.

USDA Risk Management Agency has created a two-page fact sheet explaining allowable deadlines for termination of cover crops to qualify the subsequent crop in the field for crop insurance.

Extension experts from Washington State University, the University of Tennessee and Texas Tech explain how biodegradable plastic mulches are made; how biodegradability is measured; current techniques on evaluating biodegradable mulches; and research and policy progress to date. The purpose is to inform agricultural professionals, farmers, and policy makers about the suitability of biodegradable plastic mulches for use in certified organic agriculture.In October 2012, the National Organic Standards Board recommended that biodegradable mulch be added to the National Organic Program’s list of approved substances. NOP has stated it is working to include this on the approved synthetic list for crops, sometime in the next year.  The NOSB recommendation is:
§205.601(b)(2) Mulches:
(iii) Biodegradable biobased mulch films to be reviewed meet the following criteria:

(A) Completely biodegradable as shown by:

      1. meeting the requirements of ASTM Standard D6400 or D6868 specifications, or of other international standard specifications with essentially identical criteria, i.e. EN 13432, EN 14995, ISO 17088; and
      2. Showing at least 90% biodegradation in soil absolute or relative to microcrystalline cellulose in less than two years, in soil, tested according to ISO 17556 or ASTM 5988;

(B) Must be biobased with content determined using the ASTM D6866 method;

(C) Must be produced without organisms or feedstock derived from excluded methods; and

(D) Grower must take appropriate actions to ensure complete degradation.

Biobased: organic material in which carbon is derived from a renewable resource via biologicalprocesses. Biobased materials include all plant and animal mass derived from carbon dioxide recently fixed via photosynthesis, per definition of a renewable resource (ASTM).


From the Organic Broadcaster:

On-farm habitat for beneficial insects provides multiple benefits
July | August 2020

Insect pollinators are essential to the production of more than two-thirds of the world’s crop species and contribute $20 billion annually to U.S. agriculture. Predatory and parasitoid insects provide another $4.5 billion in free pest management. The Xerces Society has been creating a network of on-farm demonstration sites that showcase a wide variety of pollinator habitat options and installation methods. Read more.


Agriculture Resilience Act intends to build resilient farming, food systems
July | August 2020

The COVID-19 pandemic has exposed the vulnerabilities of our current food and farming systems to sudden disruptions. The Agricultural Resilience Act would bring federal policy in line with the goal of transforming American agriculture to better rebound and adapt to disruptions. Read more.


New demonstration farms in Illinois to showcase commercial-scale agroforestry
May | June 2020

The dual-purpose nature of agroforestry practices can make them a win-win for farmers, allowing them to harvest multiple products from the same land area and access new sources of income. To show farmers how agroforestry can be managed on a commercial scale, the Savanna Institute is establishing three demonstration farms across Illinois. Read more.


Spring offers tight window for planting cover crops—follow these tips
March | April 2018

Windows to incorporate cover crops into a rotation can be very tight and dependent on favorable weather conditions and maximizing a short growing seasons for marketable crops.  Read more.


Agroecologists focus on soil health to improve production
September | October 2017

Can food production and the greater benefits of ecological services (nutrient cycling, maintaining or enhancing water quality habitat for fish and wildlife, etc.) co-exist, even on the same parcel of land? Read more.


Researcher explains factors to consider when rolling-crimping rye
July | August 2017

University of Wisconsin Organic Cropping Systems Specialist Erin Silva has a long list of important factors to consider when rolling-crimping rye, derived from more than 10 years of research. She’ll be sharing some tips at an organic field day on Thursday, Aug. 31. Read more.


Diverse mix of livestock, crops helps this organic farm thrive
July | August 2016

I grew up on a typical Midwestern farm in the middle of the 20th century when most farms still had a diverse mix of crops and livestock, were mostly self-sufficient and provided a comfortable lifestyle for a sizable number of Americans. Diversity was just common sense. Read more.


IntercroppingReduced tillage, cover crops, manures help build soil health
May | June 2016

Many aspects of soil health are driven by inherent soil factors, such as clay content, the parent material of the soil, or the landscape position. The good news is that many of these factors can be improved through changes in management practices. Read more.


Rolled vetch with volunteer ryeCover crop mixes offer benefits as well as drawbacks
March | April 2016

Cover crops have become a hot topic for a wide diversity of farming systems as their benefits in nutrient cycling, weed management, erosion prevention, and as a source of nitrogen and habitat for beneficial insects become better known. Read more.


Experiment explores impact of amendments on soil microbial communities
March | April 2016

Organic farming is based on the understanding that soils are not just a place for plants to sit—they are complex living systems, home to an enormous diversity of organisms from the tiniest bacteria to earthworms and insects. Read more.


Research No-till soy early-seasonResearch at Iowa State University shows how no-till works in organic system
November | December 2015

On organic farms, no-tillage systems had been constrained by the prohibition of herbicides to terminate cover crops. To overcome this barrier….  Read more.


Research evaluates green manures as fertilizer in organic soybean-winter wheat-corn rotation
September | October 2015

To maintain soil fertility in soybean-winter wheat-corn rotations under organic management, it’s common to apply animal manure after winter wheat harvest in time for next season’s corn. Read more.


On-farm composting works best on small-scale farms
May | June 2015

At its simplest, composting is gathering plant materials in a large pile or container, letting them decompose, and using the final product to condition soil. Read more.


Sunn hemp gains popularity as a stress-tolerant cover crop
May | June 2015

Sunn hemp is a fast-growing, nitrogen-fixing soil builder that Midwest growers are just starting to appreciate as a cover crop.  Read more.


Small grains in crop rotation offer many benefits
January | February 2015

Multiyear crop rotations are a central tenet of organic crop production, and for good reason.  Read more.


Organic farming practices work with soil’s natural processes
November | December 2014

The idea that nutrients are depleted from soil when crops are harvested is not correct. Nutrients are removed when plants are harvested, but this doesn’t mean the soil has no nutrients left.  Read more.


Dairy farmer shows how he transitioned CRP land to corn, soybeans, grains
September | October 2014

Marvin Lynch, an organic dairy farmer from Cascade, Iowa, hosted a field day July 15, to share how he transitioned CRP (Conservation Reserve Program) land into organic production.  Read more.


Innovative system uses composting process to heat high tunnel

High tunnels allow vegetable farmers to extend the growing season, but often require supplemental heat to protect plants during spring and fall cold spikes. Read more.


Research explores potential benefits of mixing cover crops
July | August 2014

The potential benefits of using cover crops are wide ranging and well documented. The potential benefits of using cover crop mixtures, however, have been less thoroughly explored. Read more.


Research looks to cover crops to alleviate soil compaction, suppress weeds
May | June 2014

Rotary hoeing and in-row cultivation during the grain growing season help suppress weed populations. Read more.


What you need to know before buying/building irrigation system
May | June 2014

With the changing climate delivering hotter, drier summers, many farmers are seeking solutions by irrigating crops. Read more.


ambrosiatrifLearn the mysterious language of weeds
March | April 2014

By observing the weeds growing in your fields you can better understand your soil’s ecosystem and nutrient profile.  Read more.


Woody weedsEvaluate CRP land with ‘open eyes’ before converting to organic
January  | February 2014

Converting Conservation Reserve Program (CRP) land to organic production looks attractive: the land is already certifiable….  Read more.


215.4Radishes – A New Cover Crop for Organic Farming Systems
September/October 2013

Over the past decade, radishes have been redefined; once known almost exclusively as a pungent vegetable, radishes….  Read more.


Chris's Field Day 044The Pathogen Path: Water-Soil-Plant
September/October 2013

Food safety, as we’ve learned to talk about it in the wake of troubles like the 2006 E. coli 0157:H7 outbreak from spinach….  Read more.



New Tool for Organic Growers: PuraMaize Blocks GMO Contamination
May/June 2013

One of the challenges organic farmers face is the potential of organic crop contamination….  Read more.

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