Struffert Anne M, Rubin John C, Fernández Fabián G, Lamb John A
J Environ Qual. 2016 Sep;45(5):1557-1564. doi: 10.2134/jeq2016.03.0105.
Groundwater contamination from NO-N leaching in corn ( L.) production with coarse-textured soils poses an environmental concern. Our objectives were to evaluate NO-N leaching in continuous corn (CC), corn after soybean ( L.) (CSb), and soybean after corn (SbC) in irrigated sandy soils in Minnesota related to (i) N rate using best management practices of split-N application, (ii) a split-N application and single preplant applications of enhanced-efficiency fertilizers (EEF), and (iii) residual N treatment in SbC. Urea (0-315 kg N ha in 45-kg increments) was broadcast as a split application (half at preplant and half at the V4 development stage) and polymer-coated urea (ESN), ESN/urea, and SuperU at preplant at a rate of 180 kg N ha on an Arvilla sandy loam soil. In May and June, 75% of the total drainage and 73% of the total NO-N leached occurred. At the economic optimum N rate (EONR), season-long NO-N leaching rates were 86 and 106 kg NO-N ha for CC and CSb, respectively. In CC, reducing the EONR by 20% reduced grain yield by 4% and NO-N leached by 9%, and a 25% reduction in EONR resulted in an additional 2% reduction for both, whereas no significant reductions occurred for CSb. Similar NO-N leaching occurred with EEFs and the split-N application. After 4 yr of no N application, we measured 9 to 20 mg NO-N L and leaching of 21 to 51 kg NO-N ha, highlighting the difficulty of meeting drinking water quality standards in corn cropping systems.
在质地粗糙的土壤中种植玉米时，硝态氮淋失导致的地下水污染引发了环境问题。我们的目标是评估明尼苏达州灌溉砂质土壤中连作玉米（CC）、玉米后种大豆（CSb）以及大豆后种玉米（SbC）模式下的硝态氮淋失情况，这些情况与以下因素相关：（i）采用氮肥分次施用的最佳管理措施时的施氮量；（ii）氮肥分次施用以及单次种植前施用增效肥料（EEF）；（iii）SbC模式下的残氮处理。在阿维拉砂壤土上，尿素（0至315千克氮/公顷，以45千克为增量）作为分次施用（种植前施一半，V4发育阶段施一半），而聚合物包膜尿素（ESN）、ESN/尿素和SuperU在种植前以180千克氮/公顷的用量施用。在5月和6月，总排水量的75%以及总硝态氮淋失量的73%发生。在经济最佳施氮量（EONR）下，CC和CSb模式下整个生长季的硝态氮淋失率分别为86和106千克硝态氮/公顷。在CC模式中，将EONR降低20%会使谷物产量降低4%，硝态氮淋失量降低9%，而EONR降低25%会使两者进一步分别降低2%，而CSb模式下则没有显著降低。EEF和氮肥分次施用的硝态氮淋失情况相似。在4年不施氮肥后،我们测得硝态氮含量为9至20毫克/升，硝态氮淋失量为21至51千克/公顷，这凸显了在玉米种植系统中达到饮用水水质标准的困难。
