Cover crop-based, organic rotational no-till (CCORNT) corn and soybean production is becoming a viable strategy for reducing tillage in organic annual grain systems in the mid-Atlantic, United States. This strategy relies on mechanical termination of cover crops with a roller-crimper and no-till planting corn and soybean into cover crop mulches. Here, we report on recent research that focuses on integrated approaches for crop, nutrient and pest management in CCORNT systems that consider system and regional constraints for adoption in the mid-Atlantic. Our research suggests that no-till planting soybean into roller-crimped cereal rye can produce consistent yields. However, constraints to fertility management have produced less consistent no-till corn yields. Our research shows that grass-legume mixtures can improve N-release synchrony with corn demand and also improve weed suppression. Integration of high-residue inter-row cultivation improves weed control consistency and may reduce reliance on optimizing cover crop biomass accumulation for weed suppression. System-specific strategies are needed to address volunteer cover crops in later rotational phases, which result from incomplete cover crop termination with the roller crimper. The paucity of adequate machinery for optimizing establishment of cash crops into thick residue mulch remains a major constraint on CCORNT adoption. Similarly, breeding efforts are needed to improve cover crop germplasm and develop regionally-adapted varieties.

Core Ideas Legume and small grain cover crops are combined in mixture to provide N fertility and weed suppression for the following cash crop. In environments where winter pea growth is not restricted by cold, winter pea can produce as much biomass in mixture with small grains as crimson clover and hairy vetch. Hairy vetch was the most competitive legume with the small grains across environments and restricted small grain biomass production. The variability in total biomass composition across environments in this study demonstrates the importance of site specific cover crop species selection and mixture seeding rate recommendations. Legume and small grain cover crop mixtures may simultaneously fix N and suppress weeds. Studies were conducted from 2015 to 2017 in Maryland and North Carolina to compare winter pea (Pisum sativum L.) to crimson clover (Trifolium incarnatum) and hairy vetch (Vicia villosa Roth) for cover crop use in mixture with small grains. Five winter pea genotypes, one crimson clover cultivar, and one hairy vetch cultivar were screened in mixture with barley (Hordeum vulgare), oats (Avena sativa), and wheat (Triticum aestivum). Cold injury of the pea genotypes in Maryland severely impacted pea biomass. Peas were able to recover from cold injury in North Carolina. A robustly growing small grain aided in legume cold tolerance in some environments. In the Coastal Plain environments, all legume genotypes generally contributed to at least 50% of mixture biomass production. In the Maryland and Piedmont environments, the small grain dominated the cover crop mixture. Oats were generally more competitive with the legume species than barley or wheat. In the North Carolina Coastal Plain and Piedmont, several winter pea genotypes produced as much biomass in mixture as crimson clover and hairy vetch. Hairy vetch was the most competitive legume with the small grains across environments. The variability in total biomass composition across environments in this study demonstrates the importance of site specific cover crop species selection and mixture seeding rate recommendations.

Core Ideas Grass and legume cover crops are combined for weed and fertility management. A cereal rye and hairy vetch mixture provided more than 7500 kg ha−1 biomass. Additional fertility is necessary to maximize cover‐crop based organic corn yield. Subsurface banding feather meal is an option to increase organic corn yield. If cover crop biomass is low, providing adequate N fertility is critical for yield. Grass and legume cover crops are combined in mixtures to provide both weed and N fertility management in organic production; however, additional N fertility may be required to maximize corn yield. The research was conducted in Beltsville, MD; Kinston, NC; and Salisbury, NC; from 2012 to 2014 to evaluate the effect of starter fertilizer source and application method on weed competition and grain yield in cover crop‐based, organic corn production. Fertility treatments included high rate broadcast poultry litter (Plant available nitrogen [PAN] = 160 kg ha−1), low rate broadcast poultry litter (PAN = 72 kg ha−1), subsurface banded feather meal (PAN = 80 kg ha−1), subsurface banded poultry litter (PAN = 12 kg ha−1), and no starter fertility. A cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) mixture was established in the fall and was terminated using a roller‐crimper before corn planting. Cover crop biomass more than 7500 kg ha−1 provided excellent weed suppression. In a combined analysis of five environments, corn N content and yield followed the same pattern of high rate broadcast poultry litter > low rate broadcast poultry litter = subsurface banded feather meal > subsurface banded poultry litter = no starter fertility. Results from this study indicate that starter fertilizer is necessary to maximize corn yield in cover crop‐based organic corn production and that decisions regarding additional fertility will need to be dynamic based on site history, cover crop biomass production, and the ability to broadcast poultry litter.

Core Ideas Cereal rye/crimson clover cover crop mixtures can be used for weed suppression and soil moisture conservation in cotton production.Cover crop management at cotton planting can influence cotton emergence, weed suppression, and soil moisture dynamics.Cotton emergence declined when cotton was planted directly into standing cover crop and without row cleaners engaged, but this reduction did not affect cotton lint yield.Soil temperature was reduced and soil moisture was increased by the presence of a cover crop mulch regardless of cover crop residue management strategy at cotton planting.Cover crop residue management did not affect cotton lint yield when herbicides were used, indicating that conventional producers have flexibility in terminating cover crops and residue management at cotton planting. Cover crop residue management can affect performance of the subsequent crop. This experiment was conducted in five environments in North Carolina from 2014 to 2016 to determine the effect of a cereal rye (Secale cereale)/crimson clover (Trifolium incarnatum) mulch on cotton (Gossypium hirsutum L.) emergence, soil temperature, soil moisture, weed suppression, and cotton yield under a conventional and organic weed control context. The cereal rye and crimson clover mixture was planted in mid‐October and terminated 1 wk prior to cotton planting using a roller‐crimper or herbicide application. Cover crop residue management included fertilized, rolled cover crop with row cleaners engaged at planting (Roll+F+RC), rolled cover crop with row cleaners engaged at planting (Roll+RC), rolled cover crop (Roll), standing cover crop with row cleaners engaged at planting (Stand+RC), and no cover crop (BARE). Weed treatments included with and without herbicides. Cover crop dry biomass ranged from 3820 to 6610 kg ha−1 across environments. Fertilizing the cover crop enhanced cover crop dry biomass production by 250 to 1860 kg ha−1. Cotton emergence declined when cotton was planted directly into standing cover crop and without row cleaners engaged. Soil temperature was reduced and soil moisture was increased by the presence of a cover crop. Cover crop residue management did not affect late‐season weed biomass at four of the five environments. Cover crop residue management did not affect cotton lint yield when herbicides were used, indicating that conventional producers have flexibility in terminating cover crops and residue management at cotton planting.

Cotton growers commonly use glufosinate-based programs to control glyphosate-resistant Palmer amaranth. Palmer amaranth must be small (≤7.5 cm) for consistent control by glufosinate, and growers often miss the optimum application timing. XtendFlex™cotton may provide growers a tool to control larger Palmer amaranth. Glufosinate, dicamba, and glufosinate plus dicamba were compared for Palmer amaranth control in a rescue situation. Herbicides were applied to 16- to 23-cm weeds (POST-1) followed by a second application (POST-2) 12 d later. Glufosinate-ammonium at 590 g ai ha−1plus dicamba diglycolamine salt at 560 g ae ha−1POST-1 followed by glufosinate plus dicamba POST-2 was more effective than glufosinate at 880 g ha−1POST-1 followed by glufosinate at 590 g ha−1POST-2 or dicamba alone applied twice. Following a directed layby application of glyphosate, diuron, andS-metolachlor 14 d after POST-2, Palmer amaranth was controlled 99% by any system containing dicamba or glufosinate plus dicamba POST-1 followed by dicamba, glufosinate, or glufosinate plus dicamba POST-2 compared with 87% to 91% control by glufosinate alone applied twice. Cotton height and number of main stem nodes at layby were reduced in systems with dicamba only POST-1 followed by dicamba or glufosinate plus dicamba POST-2, presumably due to competition from the slowly dying Palmer amaranth with dicamba only POST-1. These treatments also delayed cotton maturity and reduced lint yield compared with systems containing glufosinate plus dicamba at POST-1.