Dual‐use cover/green manure (CGM) crops and animal manure are used to supply nitrogen (N) and phosphorus (P) to organically grown field crops. A comprehensive review of previous research was conducted to identify how CGM crops and animal manure have been used to meet N and P needs of organic field crops, and to identify knowledge gaps to direct future research efforts. Results indicate that: (a) CGM crops are used to provide N to subsequent cash crops in rotations; (b) CGM‐supplied N generally can meet field crop needs in warm, humid regions but is insufficient for organic grain crops grown in cool and sub‐humid regions; (c) adoption of conservation tillage practices can create or exacerbate N deficiencies; (d) excess N and P can result where animal manures are accessible if application rates are not carefully managed; and (e) integrating animal grazing into organic field crop systems has potential benefits but is generally not practiced. Work is needed to better understand the mechanisms governing the release of N by CGM crops to subsequent cash crops, and the legacy effects of animal manure applications in cool and sub‐humid regions. The benefits and synergies that can occur by combining targeted animal grazing and CGMs on soil N, P, and other nutrients should be investigated. Improved communication and networking among researchers can aid efforts to solve soil fertility challenges faced by organic farmers when growing field crops in North America and elsewhere.

Wheat (Triticum spp.) dominates dryland grain crop production in the North American Great Plains and other regions with semi‐arid steppe climates. A common practice is to alternate winter or spring wheat with a 14‐ to 21‐mo fallow period to allow for soil‐water recharge, despite economic inefficiencies and environmental degradation. Replacing fallow with non‐cereal grain and seed crops often reduces future wheat yields due to increased water stress during grain fill. The use of annual forages may not have the disadvantages associated with grain and seed crops. The objective of this review was to determine benefits and challenges of incorporating annual forages into dryland wheat systems in semi‐arid steppe climates, using the Great Plains within the United States as a model system. Results indicate that: (a) cool‐ and warm‐season, annual grass and broadleaf species can be grown for forage across the region; (b) forage production will be less risky than grain and seed crop production under predicted climate‐change scenarios; (c) grazing annual forages may offer advantages (e.g., nutrient cycling, improved soil structure, added revenue from livestock) over mechanically harvesting annual forages; (d) the lack of infrastructure and local markets impede the use of annual forages to diversify wheat‐based cropping systems in the region; and (e) limited networking among researchers hinders the advancement in knowledge on how annual forages can be used to improve dryland wheat system resilience.

Lentil (Lens culinaris Medik.) is an important source of protein, starch, and mineral nutrients in many parts of the world. However, the impact of environment and cultivar on the enrichment of these nutrients is not well understood. Four lentil cultivars (‘Avondale’, ‘CDC Richlea’, ‘CDC Maxim’, and ‘CDC Imvincible’) varying in color, seed size, and maturity were evaluated at five Montana locations with diverse climatic and soil conditions over 3 yr. Significant cultivar, location, and year effects were found for yield, protein, starch, and minerals. Grain protein concentration was the highest at Moccasin (262 g kg⁻¹) and lowest at Richland (246 g kg⁻¹), whereas starch concentration was the highest at Richland (455 g kg⁻¹) and lowest at Moccasin (441 g kg⁻¹). Among cultivars, Avondale was the top yielding cultivar (1965 kg ha⁻¹) and adaptable to most of the environments; CDC Imvincible was the top protein producer (265 g kg⁻¹); and CDC Richlea is the leading starch producer (456 g kg⁻¹). Grain protein concentration was negatively correlated with starch. Lentil grains varied in nutrient concentrations across locations, with the northcentral Montana region producing 10‐ to 20‐times greater selenium concentration than other locations. CDC Maxim had the highest iron (62.1 mg kg⁻¹) and zinc (31.5 mg kg⁻¹) concentrations. Seed protein concentration was positively correlated with phosphorus, sulfur, copper, and boron. Seed starch is positively correlated with magnesium and manganese. Results suggest that plant breeding and production site selection could enrich lentil nutrient concentrations to help combat malnutrition in the world.

Rotating cereal crops (e.g., wheat [Triticum aestivum L.] with a 10‐ to 21‐mo summer fallow period [fallow]) is a common farming practice in dryland (rainfed) agricultural regions. Fallow is associated with several challenges including low precipitation storage efficiency, depletion of soil organic carbon (SOC), loss of soil fertility, little crop residue retention and soil erosion, and few control options for herbicide‐resistant (HR) weeds. The inability to effectively control HR weeds poses a major challenge to maintaining soil and water conservation practices such as no‐tillage, as some producers are considering tillage to control weeds. Cover crop (CC) integration into wheat‐based production systems to replace portions of the fallow period provides an opportunity to increase SOC, improve soil fertility, suppress weeds, and increase profitability of dryland crop production, especially when CCs are used as forage. This forum paper used the North American Great Plains as a model region to review information on (a) challenges of dryland agriculture; (b) integrating CCs in dryland agriculture; (c) benefits, challenges, and limitations of CCs in dryland crop production; (d) management options for CC integration in dryland grain systems; and (e) recommendations for future research efforts.

There is interest in reducing or even eliminating tillage in organic production systems. In this special Issue, research teams in Europe and North America summarize recent and on-going efforts to develop conservation-tillage systems that can be used on commercial organic farms. While progress is being made in the development of organic no-tillage (no-till) systems, considerable work still needs to be done before there will be wide-spread adoption by organic farmers.