Management and assessment of winter cover crop systems for supplying nitrogen to corn in the mid-Atlantic region of the United States
Vaughan, Jeffrey David
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Research examining cover crop-corn systems focuses on corn planted into chemically desiccated cover crop residue using no-tillage practices. Two field studies including rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), and rye+hairy vetch cover crops were established to determine the influence of cover crop management on N availability to corn (Zea mays L.). The presidedress soil nitrate test (PSNT) and the Nitrate Quick Test were utilized to determine their viability for making N fertilizer recommendations in cover cropcorn systems. Soil N concentrations peaked in the majority of cover crop treatments at the corn four to five leaf stage. Delaying cover crop desiccation from early flowering of rye (early) to early flowering of vetch (late) caused an increase in biomass accumulation in all cover crop treatments, but an increase in N accumulation only in vetch. Vetch provided more plant available N, less soil moisture conservation, and higher corn yields than cover crops including rye. Early desiccation enhanced plant available N, soil moisture, and corn yield. Mowing cover crop residue enhanced plant available N, soil moisture, and corn yield. The PSNT was a viable method of assessing corn N sufficiency in cover crop systems, but sampling to a depth of 15 cm was adequate. The Nitrate Quick Test was accurate in determining soil nitrate concentrations, but accuracy decreased as soil nitrate decreased.
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