TY - JOUR

T1 - Minimizing nitrate leaching while maintaining crop yields

T2 - Insights by simulating net N mineralization

AU - Heumann, Sabine

AU - Fier, Annegret

AU - Haßdenteufel, Martin

AU - Höper, Heinrich

AU - Schäfer, Walter

AU - Eiler, Tim

AU - Böttcher, Jürgen

N1 - Funding information: Acknowledgments The field experiment was funded by the water withdrawal fee (Wasserentnahmegebühr) of the state of Lower Saxony and was carried out by the Chamber of Agriculture of Lower Saxony (LWK) and the State Authority for Mining, Energy and Geology (LBEG) in Hannover. Therefore, the work of Jutta Klaukien and Bernd Luers is deeply acknowledged. Thanks to the anonymous reviewers the original manuscript was significantly improved.

PY - 2013/4

Y1 - 2013/4

N2 - Nitrate leaching from agricultural fields still is a serious threat in temperate regions, as it often causes an exceeding of the legal nitrate threshold in the groundwater. It was often proposed to lower mineral nitrogen (N) fertilization, but suboptimal N rates are usually associated with severe yield losses. Here it was hypothesized that the crop type has a strong impact on the relation between N leaching and yield, besides N fertilizer rates, due to crop-specific use of N mineralized from soil organic matter. We analysed N leaching and yield data of a field trial in NW-Germany with five mineral N fertilizer levels and a crop rotation of silage corn, winter barley and winter rye from 12 years. Net N mineralization was calculated with an N mineralization model, that allowed site-specific estimations, and with a balance approach based on measured field data. Yield and N leaching of the three crops strongly depended upon N supply, but N leaching could not be totally avoided even without any N fertilization, since for each crop type N leaching showed relatively constant values below an N supply of ca. 150 kg N ha-1. Secondly, the possibility of minimizing N leaching with concurrent modest reduction in yield (not more than 10 %) depended upon crop-specific use of mineralized N. Thirdly, these reductions appear to be most probable for silage corn due to 2-4 times higher N uptake in unfertilized plots (mean: 87 kg N ha-1) compared to the cereals (mean: 31 kg N ha-1). Thus there is a strong need to include estimates for net N mineralization in fertilizer recommendations, especially for corn, in order to more efficiently use mineralized N and reduce nitrate leaching. This is evident for the kind of sandy soil studied, and even stronger for soils with finer texture and consequently higher net N mineralization potential.

AB - Nitrate leaching from agricultural fields still is a serious threat in temperate regions, as it often causes an exceeding of the legal nitrate threshold in the groundwater. It was often proposed to lower mineral nitrogen (N) fertilization, but suboptimal N rates are usually associated with severe yield losses. Here it was hypothesized that the crop type has a strong impact on the relation between N leaching and yield, besides N fertilizer rates, due to crop-specific use of N mineralized from soil organic matter. We analysed N leaching and yield data of a field trial in NW-Germany with five mineral N fertilizer levels and a crop rotation of silage corn, winter barley and winter rye from 12 years. Net N mineralization was calculated with an N mineralization model, that allowed site-specific estimations, and with a balance approach based on measured field data. Yield and N leaching of the three crops strongly depended upon N supply, but N leaching could not be totally avoided even without any N fertilization, since for each crop type N leaching showed relatively constant values below an N supply of ca. 150 kg N ha-1. Secondly, the possibility of minimizing N leaching with concurrent modest reduction in yield (not more than 10 %) depended upon crop-specific use of mineralized N. Thirdly, these reductions appear to be most probable for silage corn due to 2-4 times higher N uptake in unfertilized plots (mean: 87 kg N ha-1) compared to the cereals (mean: 31 kg N ha-1). Thus there is a strong need to include estimates for net N mineralization in fertilizer recommendations, especially for corn, in order to more efficiently use mineralized N and reduce nitrate leaching. This is evident for the kind of sandy soil studied, and even stronger for soils with finer texture and consequently higher net N mineralization potential.

KW - Apparent N mineralization

KW - Corn

KW - Crop-specific N uptake

KW - Northern Germany

KW - Suboptimal N fertilization

UR - http://www.scopus.com/inward/record.url?scp=84880600282&partnerID=8YFLogxK

U2 - 10.1007/s10705-013-9572-y

DO - 10.1007/s10705-013-9572-y

M3 - Article

AN - SCOPUS:84880600282

VL - 95

SP - 395

EP - 408

JO - Nutrient cycling in agroecosystems

JF - Nutrient cycling in agroecosystems

SN - 1385-1314

IS - 3

ER -