Nitrate Leaching as Influenced by Cover Cropping and Nitrogen Source

Abstract

To minimize groundwater contamination by NO−3 and to maximize efficient crop N use, it is necessary to better characterize NO−3 leaching in various cropping systems. Our objectives were to compare the contributions of hairy vetch (Vicia villosa Roth) and NH+4 N sources to NO−3 leaching in corn (Zea mays L.) production, and to compare NO−3 leaching losses in a corn production system utilizing hairy vetch as a N source and winter cover crop with leaching losses in one utilizing an NH+4 N source and a rye (Secale cereale L.) cover crop. Nitrogen, sometimes enriched with 15N, was applied to corn grown on a Maury silt loam (fine, mixed, mesic Typic Paleudalf) in lysimeters as vetch‐ or NH+4‐N at rates between 10.5 and 14.0 g N m−2 yr−1. Treatments (N source/cover crop) were: NH+4‐N/fallow, vetch‐N/fallow, NH+4‐N/rye, and vetch‐N/vetch; mean 3‐yr cumulative NO−3 leaching losses were 6.11, 4.85, 0.35, and 2.51 g N m−2, respectively. Total recovery of added 15N in leachate was <5% for all treatments, and the percentage of leached NO−3 derived from labeled N sources was generally <15%. In the winter‐fallow lysimeters, effects of N source on the fraction of water input discharged, concentration of NO−3, and quantity of NO−3 leached varied with year and time of year; differences in N‐source availability and mulch effects were sometimes indicated. Generally, cover crop effects were larger than N‐source effects. The NH+4 N source/rye cover system leached consistently less NO−3 than the vetch N source/vetch cover system, even though the fraction of water discharged was not consistently different.

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

“…Winter cover cropping alters the soil water and the soil nitrate N content during the winter period (McCracken et al 1994;Parkin et al 2006) due to plant uptake, which are two main drivers and regulators of the processes in soils leading to denitrification (e.g., Ciarlo et al 2007;Dobbie and Smith 2003;Miller et al 2009;Ruser et al 2001;Skiba et al 1998). The NO 3 − concentration in soil solution influences N 2 O emissions not only by the substrate availability but also by the molar ratio of N 2 O and N 2 during denitrification: The higher the NO 3 − concentration, the lower the N 2 / N 2 O ratio (Blackmer and Bremner 1978;Miller et al 2009).…”

Desempenho da mistura forrageira de aveia-preta mais azevém e atributos químicos do solo em função da aplicação de esterco líquido de suínos

“…Conseqüentemente, as perdas por lixiviação profunda de N-NO 3 -também diminuem. Portanto, utilizar plantas com alto poder reciclador e não deixar o solo descoberto por tempo maior que 30-40 dias são formas de reduzir as perdas de N-mineral para o lençol freático e melhorar a ciclagem de nutrientes (McCracken et al, 1994;Wiethölter, 1996).…”

Decomposição e liberação de nitrogênio de resíduos culturais de plantas de cobertura de solo solteiras e consorciadas

“…A elevada taxa de amonificação, especialmente do N solúvel, poderá resultar em perdas de N por volatilização de amônia, como constataram Jansen & McGinn (1991) durante a decomposição dos resíduos culturais de lentilha (Lens culináris Medic.). Considerando que o N amonificado é rapidamente nitrificado, poderão ocorrer perdas de N também por lixiviação de N-NO 3 -, caso o volume de água das chuvas seja suficiente para ocasionar percolação de água no perfil do solo (McCracken et al, 1994;Giacomini, 2001), e por denitrificação em locais de anaerobiose no solo (Aulakh et al, 1991).…”