Organic Small Grain Production Overview

Monitoring Soil Organic Matter

Regular soil testing is essential to track changes in soil organic matter levels. It is advisable to conduct soil analyses every few years and maintain detailed records of the results. Significant alterations in soil organic matter may take several years to manifest, and it often requires a decade or more to observe measurable changes (Collins et al., 1992).

Indicators of increased organic matter include improved aggregation as evidenced by visual observation, reduced soil crusting following heavy rainfall, a darker soil hue, and enhanced crop yields during periods of drought stress.

Sorghum planted in corn residue. Photo: Darron Gaus, NCAT

Managing Crop Residue

Crop residues are a primary source of organic matter in small grain systems. Residues from crops like wheat, oats, and rye typically have high carbon-to-nitrogen (C:N) ratios, around 80:1, leading to slower decomposition compared to more succulent broadleaf plants, such as clovers and vetch, that possess a lower C:N ratio (Beggeman, 2018).

When managing crop residues in organic systems, consider the following principles:

• Keep crop residue in the field: Leaving crop residues on the field surface helps prevent soil erosion, reduces soil water loss, and enhances soil organic matter. Removing residues can lead to increased erosion and loss of valuable organic material (Mondal and Chakraborty, 2022). Additionally, in temperate climates, leaving stubble in the field can help keep the soil warmer, which is important for crops during cold winters. Warmer soil helps crops survive and speeds up germination, leading to better growth. Research on the Canadian prairies has found that fields with crop residue or cover crops stay warmer in winter and freeze at shallower depths. This can protect roots from extreme cold and help crops get a strong start in the spring (Cárceles et al., 2022).
• Ensure uniform residue distribution during harvest: Utilize chaff spreaders during harvest to distribute straw evenly across the field, avoiding windrows. This uniform coverage promotes consistent microbial activity and residue decomposition.

In subtropical and tropical regions, crop residue management requires tailored approaches due to distinct climatic conditions:

• Utilize residues as mulch: Leaving residues on the soil surface as mulch helps maintain soil moisture, suppress weeds, and regulate soil temperature. This practice is particularly beneficial in warmer climates where rapid decomposition can reduce soil cover (Huang et al., 2022).
• Incorporate cover crops: Planting cover crops with lower C:N ratios, such as legumes, can accelerate residue decomposition and enhance soil fertility. Legumes, with their lower C:N ratios, decompose more rapidly, providing nitrogen to the soil.
• Avoid residue burning: Burning is sometimes practiced for rapid field clearing, but it leads to nutrient loss and air pollution. Alternative methods, such as mulching (Ruiz Diaz and Presley, 2021) or composting, are more sustainable and preserve soil health.

Implementing these residue-management strategies, adapted to specific climatic conditions, can significantly improve soil health and productivity in small grain systems.

Mixed cover crops. Photo: Lee Rinehart, NCAT

Using Cover Crops

When using cover crops to increase soil organic matter, it’s important to select species with a higher carbon-to-nitrogen (C:N) ratio (a higher concentration of carbon than nitrogen in plant tissue). Grasses such as cereal rye and triticale are excellent choices, as their fibrous residues break down more slowly and contribute more stable organic matter (humus) to the soil. These high C:N cover crops help build long-term soil structure and carbon reserves.

In contrast, broadleaf species like legumes decompose more quickly due to their lower C:N ratio, contributing less to long-term organic matter accumulation but providing quicker nutrient cycling, especially for nitrogen. While they are not typically used to build humus, broadleaf cover crops like buckwheat can play a complementary role in soil health. Buckwheat is a fast-growing crop known for its ability to scavenge and make phosphorus and other nutrients more available from the soil. Its quick biomass production and aggressive weed suppression make it ideal for short windows in rotations. Though it decomposes quickly and adds less stable organic matter, buckwheat is a valuable tool in organic systems for nutrient cycling and soil fertility management. Additionally, annual ryegrass (Lolium multiflorum) is a cool-season grass cover crop that plays an important role in phosphorus cycling. Its dense, fibrous root system improves soil structure and helps pull phosphorus from parts of the soil where it might otherwise be unavailable to plants. Research has shown that annual ryegrass can recover and recycle a significant amount of phosphorus—up to 42% of what the next crop might need—by breaking down its residues after termination (Hansen et al., 2022). This means ryegrass not only helps capture nutrients while it’s growing but also continues to benefit the soil and future crops as it decomposes. Its fast growth also makes it a great option for preventing erosion and holding onto nutrients during the cool season.

Small grain cover crop in almond orchard to be bailed for hay. Photo: Rex Dufour, NCAT

Combining high C:N and low C:N cover crops in a rotation—or even in a mix—can maximize benefits by improving both nutrient availability and long-term soil health. For instance, cereal rye and hairy vetch or red clover are excellent combinations that provide high biomass and the C:N benefits of both species.

For an overview of using cover crops and their effect on soil organic matter, check out the ATTRA publications Overview of Cover Crops and Green Manures and Cover Crops for Hot and Humid Areas.

Animal Manure

The benefit of manure to soil organic matter varies based on the manure type and its specific composition. Factors such as the animal’s diet and the inclusion of bedding materials significantly influence manure quality. For example, solids like beef manure and poultry litter typically contain higher concentrations of organic matter, compared to more diluted slurry and liquid forms. To estimate the contribution of organic matter from manure, it’s common to consider that a portion of the manure’s organic matter will decompose within a year, with the remaining fraction contributing to soil organic matter (Johnson, 2022). For more information about how to use manure in your organic system, please refer to the ATTRA publication Manure in Organic Production Systems.

Compost

The organic-matter content of compost varies widely, typically ranging from 30% to 70%, depending on the materials used to make the compost. A laboratory analysis can determine the exact organic matter content of a specific compost batch. Due to its relatively high organic matter levels, compost can add a substantial amount of organic matter to the soil, similar to that of a high-carbon cover crop. However, sourcing enough compost can be challenging for large-scale organic grain farmers.

Rate of Organic Matter Decomposition

The rate at which organic matter decomposes is crucial for soil health. Rapid decomposition can lead to a quick release of nutrients, leaving minimal organic matter in the soil over time. Conversely, slow decomposition can result in excessive residue that immobilizes nutrients, a process where soil microbes tie up essential nutrients, particularly nitrogen, as they break down high-carbon materials like straw or wood chips. During immobilization, microbes consume available nitrogen to meet their own needs for breaking down carbon-rich residues, making that nitrogen temporarily unavailable to plants. This can lead to nutrient deficiencies in crops until microbial activity stabilizes and starts to release nutrients back into the soil. The goal is to achieve a consistent, steady rate of decomposition that balances nutrient availability with long-term organic matter buildup.

Rolling-crimping rye cover crop with a walk-behind tractor using roller-crimper attachment. Photo: Andy Pressman, NCAT

Several factors influence the rate of active organic matter decomposition, including climate and tillage practices.

Climate

Climatic factors such as temperature and moisture influence soil organic matter levels. Generally, as annual precipitation increases, soil organic matter levels rise due to increased plant biomass and residue inputs. Conversely, higher average temperatures can accelerate organic matter decomposition, potentially leading to lower soil organic matter levels. This is because microbial activity, responsible for decomposing organic matter, is enhanced in warmer conditions (Magdoff and van Es, 2021). Although farmers cannot change their location, understanding the climatic influences where they operate is essential. In regions with higher decomposition rates, more frequent additions of organic matter may be necessary to maintain soil health.

Tillage Practices

Tillage significantly impacts organic matter decomposition. It disrupts soil structure, incorporates oxygen, and accelerates the breakdown of organic matter. Excessive tillage can lead to increased decomposition rates, reducing soil organic matter levels and increasing the risk of erosion. Reducing or eliminating tillage can help preserve soil organic matter by maintaining soil structure and reducing erosion risks. However, carefully managed tillage in low-precipitation areas is sometimes necessary to bury excess surface reside that is not decomposing. It’s important to use the tillage method that suits your crops, tools, and region to ensure minimal disturbance to the soil structure and soil biology.

This presents a challenge for organic grain production, which often relies on tillage for weed control. Balancing weed management with practices that preserve soil organic matter is crucial for sustainable production (Li et al., 2024).

Managing a rye/vetch cover crop mixture with a roller-crimper at Tuckaway Farm, Lee, New Hampshire. Photo: Andy Pressman, NCAT

The Roller-Crimper

The roller-crimper is a vital tool in no-till organic farming, designed to terminate cover crops without disturbing the soil. It consists of cylindrical drums, often filled with water to adjust weight, which roll over cover crops, crimping their stems to kill them naturally while creating a protective mulch layer. This mulch helps suppress weeds, conserve moisture, and improve soil health by reducing erosion and adding organic matter as it decomposes (Bergtold and Sailus., 2020).

Proper timing of termination is critical to ensure that the cover crop contributes effectively to nutrient cycling and supports the growth of the subsequent cash crop. Terminating too early may lead to regrowth or insufficient biomass for mulching, while waiting too long can result in woody residues with limited nutrient release. The ideal practice is to terminate cover crops at flowering or the early milk stage—when biomass production is maximized and nutrient content is still relatively high—to ensure adequate fertilization and smoother decomposition in synchrony with cash crop uptake, and to ensure that the cover crop does not regrow.

There are several key considerations for effective roller-crimper use:

• Timing of termination matters: The growth stage of the cover crop at rolling is one of the most important factors for success. Research has shown that grasses like cereal rye should be terminated between late flowering and the early milk stage, while broadleaf cover crops should be rolled at peak biomass (about 2/3 into their flowering stage or as the pods begin to set) (Southern Cover Crops Council, No date). Rolling too early can result in incomplete termination, allowing the crop to regrow, while rolling too late can lead to seed production, which may cause volunteer weeds in the next planting season (Bergtold and Sailus, 2020).
• Not all cover crops respond the same: Cover crops vary in how well they respond to rolling and crimping, making timing a critical factor for successful termination. Legumes and broadleaf crops are generally more challenging to kill, with species like vetch needing at least 80% of its flowers open for crimping to be effective. Some legumes, such as crimson clover and rapeseed, often require multiple passes to fully terminate them without herbicides. On the other hand, Austrian winter pea is one of the easiest legumes to terminate, as its tender stems crimp readily.
• Synchronize mixes: When using cover crop mixes, it’s essential to choose species that mature at similar times to avoid uneven termination. If a grain reaches maturity too soon, while a legume is still flowering, the grain may set seed before rolling, and this reduces control effectiveness. To ensure the best results, select cover crop varieties with synchronized growth stages by working with seed suppliers (Southern Cover Crops Council, No date a).
• Cover crop biomass is key: A roller-crimper works best when there is sufficient plant biomass to form a thick, weed-suppressing mulch layer. For example, a rye cover crop should ideally produce at least 5,000 pounds per acre of biomass before termination. Insufficient biomass can lead to poor weed control and faster decomposition, reducing the benefits of  rolling (Bergtold and Sailus, 2020).
• Equipment setup and weight adjustment make a difference: The effectiveness of a roller-crimper depends on applying the right amount of pressure. If it’s too light, the cover crop may not be fully crimped and will regrow. If the pressure is too heavy, stems can be severed, which also leads to regrowth. Adding or removing water from the drum allows farmers to customize its weight based on field conditions and cover crop type (Panday et al., 2024).
• Mounting position can affect success: Research suggests that attaching the roller-crimper to the front of the tractor helps crimp the cover crop before it’s compressed by the tires, leading to more uniform termination. However, some farmers have had success using rear-mounted rollers for certain crops, like legumes. Choosing the right mounting position depends on the type of cover crop and field conditions (Bergtold and Sailus, 2020).

Organic farmers interested in integrating roller-crimping into their no-till systems should consider the following:

• Experiment on a small scale to determine the best timing and weight settings.
• Choose cover crops that are proven to terminate well with crimping.
• Work with local agricultural Extension services or conservation districts to access regional trial results.
• Consult organizations like the Rodale Institute for research and training on best practices.

By understanding timing, crop selection, and equipment adjustments, farmers can successfully use roller-crimpers to reduce tillage, improve soil health, and create resilient organic cropping systems. However, it’s important to recognize that roller-crimping is a nuanced practice that requires experience. Successful organic farmers often have years of cover crop management under their belts, with firsthand knowledge of how different species behave, the optimal stage for termination, and how to integrate them effectively with cash crops.

When selecting a roller-crimper, consider factors such as equipment compatibility, field conditions, and specific farming practices to ensure optimal performance. (The Further Resources section of this publication provides contact information for several roller-crimper suppliers.) Farmers can consult manufacturers and agricultural Extension services to find the best solution for their particular fields. Proper timing and equipment setup are essential to achieving a clean kill and avoiding issues like regrowth or poor seedbed conditions.

Mowing rye and vetch with a sickle bar mower. Photo: Andy Pressman, Foggy Hill Farm.

Additional Equipment for Cover Crop Management

Many farmers utilize tools such as stalk choppers, roller harrows, cultipackers, bed rollers, and land rollers—either factory-made or custom-modified—to achieve effective cover crop termination in no-till systems. Another method, swathing, involves cutting the cover crop and laying it down in windrows to dry. This technique is particularly effective in systems that integrate livestock, as the swathed cover crop can be a high-quality forage for grazing or baling for later use. Swathing offers flexibility in managing cover crops for both soil health and livestock feed, making it a practical choice for diversified operations.

Unlike conservation agriculture, which typically emphasizes keeping the soil covered with living plants or residues year-round and minimizing soil disturbance, swathing intentionally cuts the cover crop, removing some biomass from the field. While this may slightly reduce the amount of organic matter returned to the soil compared to roller-crimping or leaving residue in place, the trade-off is the added benefit of integrating livestock nutrition into the system. When managed carefully, swathing can still support soil health goals by reducing weed pressure, maintaining surface cover, and contributing nutrients through manure deposition from grazing animals.

Yield Differences Between Organic and Conventional Systems

It takes time for an ecosystem to adjust to different farming techniques. In a conventional system, there are few buffers and many inputs. (A buffer would be any biological factor that minimizes adverse conditions, such as beneficial insects, microbial activity, etc.) During the transition period, the farmer reduces off-farm inputs (pesticides and fertilizers), but the buffers are not fully developed yet. The system is unbalanced. As the rotation is established and the natural buffers increase, the system levels out and yields return to levels similar to those before the conversion.

Figure 1: Potential drop in yield during the transition period. Notice that, over time, organic yields do return to near-conventional levels, with less variability than before. Graph: Gilmore, 2009

People commonly believe that small grains, such as wheat, barley, and oats, yield less in organic systems than in conventional ones. While this observation holds true in many cases, a study by Le Campion et al. (2020) highlights that the comparison isn’t so straightforward. Yields in both organic and conventional systems are shaped by a range of factors, including region, climate, soil fertility, and management intensity, and there is considerable variation within each system.

In the United States, conventional grain production can range from high-input systems that use synthetic fertilizers and pesticides intensively, to more extensive systems with fewer inputs, particularly in drier regions. Similarly, organic farms may differ widely in nutrient management, depending on whether they have access to manure, rely on compost, or depend on cover crops to build soil fertility. In most organic systems, nitrogen availability is a primary limiting factor in achieving high yields, especially for nitrogen-hungry crops like small grains.

Across a wide range of trials, Le Campion and colleagues found that organic grain yields ranged from 44% to 96% of their conventional counterparts. Organic systems were more competitive in regions with low rainfall and naturally lower yield potential, while conventional systems outperformed in high-input, favorable environments.

While yield remains a critical factor for farmers making their living from small grain production, other dimensions of sustainability are also gaining attention, especially in the face of a changing climate. A 2022 study published by Azarbad in Frontiers in Microbiology points out that organic practices, which avoid synthetic inputs and build fertility through natural sources like plant residues and manure, tend to support more diverse and resilient soil microbial communities. These microbial populations play a key role in soil health and may help buffer crops against the adverse effects of climate stress, such as drought or nutrient loss.

Taken together, these studies suggest that although organic systems may not always match conventional yields, their potential to build long-term soil resilience and microbial activity could offer critical advantages under increasingly unpredictable climate conditions. Yield is only one part of the equation; farmers may also benefit from considering how management practices affect the biological foundation of their soils.

Ask other organic growers in your region for specific yield information.