Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur, 721302, India.
School of Infrastructure, Indian Institute of Technology, Bhubaneswar, 751013, India.
Environ Pollut. 2020 Oct;265(Pt A):114866. doi: 10.1016/j.envpol.2020.114866. Epub 2020 May 27.
Nitrogen (N) plays an important role in agriculture crop production but the increasing application of nitrogen increases the possibilities of groundwater contamination through nitrate leaching. Nitrate leaching is the inevitable part of agriculture production which occurs during nitrogen fertilization. Hence, the quantification of nitrogen fertilizer is required to reduce nitrate leaching. In this study, nitrogen transformation and transport such as ammonium (NH) and nitrate (NO) at different soil depths and maize crop growth stages were measured during field experiments for two sowing dates (timely and delay) and four N fertilization levels under irrigated (year 2013 and 2014) and rainfed (year 2012 and 2014) conditions for maize crop. NH, NO and total nitrogen concentrations were measured using spectrophotometer at 410 nm and Kjeldahl method at varying soil depths and maize crop growth stages. Thereafter, nitrogen balance approach was used to estimate the NO leaching. Results indicated that NO leaching in irrigated condition was higher 109% in N, 179% in N, and 292% in N level respectively in comparison to the N level in timely sowing date, while in delayed sowing date, leaching was higher 54% in N, 123% in N, and 184% in N level respectively in comparison to N level. In rainfed, the NO leaching was higher 30% in N, 59% in N, and 99% in N level respectively in comparison to N level for the timely sowing date, while in delayed sowing, leaching was higher 23% in N, 44% in N, and 78% in N level respectively in comparison to N level. The results indicate that leaching losses were less in timely sowing dates for both rainfed and irrigated maize. The study further reveals that sowing dates combination with N levels could be an effective management strategy to reduce NO leaching by minimizing the N fertilization.
氮（N）在农业作物生产中起着重要作用，但随着氮的不断增加，硝酸盐淋溶增加了地下水污染的可能性。硝酸盐淋溶是农业生产中不可避免的一部分，它发生在氮施肥期间。因此，需要量化氮肥的使用量以减少硝酸盐淋溶。在这项研究中，在不同的播种日期（适时和延迟）和四个氮施肥水平下，在灌溉（2013 年和 2014 年）和雨养（2012 年和 2014 年）条件下，田间试验测量了不同土壤深度和玉米作物生长阶段的氮转化和运移，如铵（NH）和硝酸盐（NO）。在不同的土壤深度和玉米作物生长阶段，使用分光光度计在 410nm 处和凯氏定氮法测量 NH、NO 和总氮浓度。此后，采用氮平衡法估计 NO 淋溶量。结果表明，与适时播种日期的 N 水平相比，在灌溉条件下，N、N 和 N 水平的 NO 淋溶分别高出 109%、179%和 292%，而在延迟播种日期，N、N 和 N 水平的淋溶分别高出 54%、123%和 184%在 N 水平。在雨养条件下，与适时播种日期的 N 水平相比，N、N 和 N 水平的 NO 淋溶分别高出 30%、59%和 99%，而在延迟播种日期，N、N 和 N 水平的淋溶分别高出 23%、44%和 78%在 N 水平。结果表明，适时播种日期下，雨养和灌溉玉米的淋溶损失较小。该研究进一步表明，播种日期与氮水平相结合可能是一种有效的管理策略，可以通过减少氮肥的使用来减少 NO 淋溶。
