Winter Cover Crop and Fall‐Applied Poultry Litter Effects on Winter Cover and Soil Nitrogen

Abstract

Increasing diversity in monoculture production through inclusion of cover crops (CC) and reducing chemical fertilizer inputs by application of animal manures could increase multiple ecosystem services and agroecosystem function. This study was designed to quantify selected ecosystem services from legume, grass, and biculture CC and poultry litter (PL) in strip‐tilled corn (Zea mays L.). Treatments included hairy vetch (Vicia villosa Roth), cereal rye (Secale cereale L.), vetch‐rye biculture, and winter fallow (WF) all with and without fall‐applied PL. Prior to CC termination and corn planting, aboveground dry matter, N content, and C/N ratios of CC and weed biomass were measured; soil inorganic N (ΣNO3− and NH4+) was analyzed every 2 wk following CC termination. Biculture transgressively over‐yielded in 2014 but not in 2015, accumulated levels of biomass N similar to vetch treatment (Vetch), suppressed weeds as effectively as rye treatment (Rye), and maintained soil inorganic N levels similar to Vetch by the second year of study. Overall, CC yield increased 20 to 30% with fall applied PL. Vetch C/N ratio decreased 14% with PL in 2015, while Rye C/N ratio was unaffected. Average weed C/N ratios were 24.5 with Rye and 16.2 with vetch + poultry litter treatment (VetchPL). Cover crop systems with Vetch showed the greatest soil inorganic N, while Rye inorganic N levels were similar to WF. Winter annual weeds were suppressed at least 92% by CC, and most effectively when Rye was present. Ultimately, optimization of cropping systems including CCs and PL will require consideration of interspecific interactions and variable responses among species. Core Ideas Cover crop yield increased 20 to 30% with fall applied poultry litter. Biculture cover crop optimized yield, nitrogen content, weed suppression, and soil nitrogen. Carbon/nitrogen ratios of vetch and weeds were affected by poultry litter and cover crop treatments. Apparent poultry litter nitrogen recovery was greatest when a legume was present. Soil inorganic nitrogen increased with vetch and poultry litter.