Premium
Use of N immobilization to tighten the N cycle in conventional agroecosystems
Author(s) -
McSwiney Claire P.,
Snapp Sieglinde S.,
Gentry Lowell E.
Publication year - 2010
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/09-0077.1
Subject(s) - cover crop , agronomy , agroecosystem , soil water , environmental science , sowing , biomass (ecology) , crop , fertilizer , crop yield , biology , agriculture , ecology , soil science
Soils in conventional agroecosystems are purposely held in a nitrogen (N)‐saturated state to maximize crop yields. Planting winter annual cover crops when fields are usually fallow has been proposed to ameliorate N losses from soils. In this study we introduced winter annual cover crops into an N rate study with plots fertilized at 0, 34, 67, 101, 134, 168, and 202 kg N/ha in maize ( Zea mays L . ) to determine how winter annual cover crops affect yields, N 2 O and NO 3 − fluxes, and N pools. At the six‐leaf stage and during flowering, incorporation of cover crop into soil resulted in a 30% reduction in maize biomass. Three weeks after fertilization, KCl‐extractable soil mineral N was 75–87% lower in cover‐cropped soils than in no‐cover soils, indicating that N had been immobilized in the cover‐cropped soils. At physiological maturity, there was no difference between cover and no‐cover treatments in crop yield, which was maximized at 9 Mg/ha in 2006 and 7 Mg/ha in 2007. Where N rates exceed crop requirements, cover crop incorporation may reduce N exports as NO 3 − and N 2 O. Tighter N cycling in conventional agroecosystems could be fostered by matching N rates to the amount of N removed with grain and using N immobilization to retain N and support yields. If N immobilization is viewed as a means for efficient fertilizer N use rather than a process that decreases crop productivity, growers might be more willing to adopt cover‐cropping practices.