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Corn nitrogen fertilization requirement and corn-soybean productivity with a rye cover crop

Abstract:

Winter rye (Secale cereale l.) cover crop (rcc) has potential to reduce no3-n loss from corn (Zea mays l.) and soybean [Glycine max (l.) Merr.] fields. However, rcc effects on annual crop productivity and corn optimal n fertilization requirement are unclear. the objectives were to evaluate corn and soybean yield response to rcc and corn optimal n rate. treatments were no-rcc and rcc with six fertilizer n rates (0-225 kg n ha-1) applied to corn in a no-till corn-soybean (cs) rotation at four Iowa sites in 2009 through 2011. the rcc biomass and n uptake was low, with a maximum of 1280 kg dry matter (dM) ha-1 and 26 kg n ha-1, respectively. in the no-n control, the rcc reduced soil profile no3-n by 15 kg n ha-1 only at time of rcc control before corn planting. corn canopy sensing, plant height, and plant population indicated more n stress, reduced plant stand, and slower growth with rcc. the rcc reduced corn grain yield by 6% at the economic optimum n rate (eonr). the eonr was the same with no-rcc and rcc, but plant n uptake efficiency (Pue) was reduced at low n rates with rcc, but not above the eonr. soybean yield was not affected by rcc. results indicate n fertilization rate should be the same with or without rcc. improvement in rcc systems and management could make rcc a more viable practice within notill corn and soybean production.