Commodity Cover Crop Nitrogen Management Effects on Winter Barley in the Mid‐Atlantic Coastal Plain

Abstract

Interest in harvestable cover crop systems, where producers apply no fertilizer until after 1 March, has increased in the mid‐Atlantic region in response to greater demand for winter cover crops. However little is known about how this practice will affect barley (Hordeum vulgare L.) yield and residual soil N. Seven research trials over 2 yr compared: (i) standard intensive management (SIM) (both fall and spring N application); (ii) No fall N, a single spring N application; and (iii) Cover N (no N application) effects on winter barley plant biomass (PB), plant nitrogen uptake (PNU), grain yield, residual soil nitrate (RSN) and ammonium (RSA). At winter dormancy (December), SIM resulted in increased PB and PNU in 2010 and higher RSN or RSA in 3 of 21 observations. At cover crop termination, SIM and the No fall N practice (five and four sites, respectively) significantly increased PNU but not RSN compared to the Cover N treatment. Similarly, SIM and No fall N produced significantly higher grain yields than the Cover N practice under normal climatic conditions (five of seven sites) with little significant effect on RSN or RSA values (7 out of 120 samples). While overall yields for the No fall N treatment were lower (8%) than SIM yields, partial net return was similar due to decreased fertilizer input. However at sites where SIM yields were significantly higher than No fall N yields (two of seven), net income for the SIM practice was $88 ha−1 greater than for no fall N.