Small grain winter cover crops for conservation of residual soil nitrogen in the mid-Atlantic Coastal Plain

Cereal rye is an effective winter cover crop because it accumulates residual soil N and reduces nitrate leaching. Wheat, barley, and triticale are alternative winter small grain species that may be managed as winter cover crops and yet produce marketable commodities. The objectives of this research were to evaluate N recovery capacity and grain yields of wheat, barley, triticale, and cereal rye grown as winter cover crops. Field plots established in 1996 and 1997 at two different locations on Maryland's mid-Atlantic Coastal Plain were amended with annual spring applications of four rates of broiler litter in a randomized complete block design with four replications. Each manure rate plot was divided into four subplots by planting four winter small grain cover crops: wheat, barley, triticale, and cereal rye. Rye cover crop treatments were killed with herbicide when the plants were 30 to 50 cm tall, while the wheat, barley, and triticale treatments continued to grow until grain maturity. Barley, rye, triticale, and wheat cover crops exhibited similar capacities to accumulate soil N, and therefore, reduce the potential for NO3—N leaching to groundwater. At the time of rye kill-down, aerial biomass N accumulation ranged from 11 to 112 kg N ha−1 and soil NO3—N levels were low (<1.5 mg NO3—N kg−1) and relatively uniform across treatments. Average barley, triticale, and wheat grain yields increased with previous broiler litter application rate and initial soil NO3—N concentration. Potential income derived from the grain and straw produced could partially or completely offset cover crop production costs.