Bélanger Gilles, Ziadi Noura, Walsh John R, Richards John E, Milburn Paul H
Agriculture and Agri-Food Canada, Soils and Crops Research and Development Centre, 2560 Hochelaga Boulevard, Sainte-Foy, Québec, Canada G1V 2J3.
J Environ Qual. 2003 Mar-Apr;32(2):607-12. doi: 10.2134/jeq2003.6070.
Nitrogen loss by leaching is a major problem, particularly with crops requiring large amounts of N fertilizer. We evaluated the effect of N fertilization and irrigation on residual soil nitrate following potato (Solanum tuberosum L.) harvests in the upper St-John River valley of New Brunswick, Canada. Soil nitrate contents were measured to a 0.90-m depth in three treatments of N fertilization (0, 100, and 250 kg N ha(-1)) at two on-farm sites in 1995, and in four treatments of N fertilization (0, 50, 100, and 250 kg N ha(-1)) at four sites for each of two years (1996 and 1997) with and without supplemental irrigation. Residual soil NO3-N content increased from 33 kg NO3-N ha(-1) in the unfertilized check plots to 160 kg NO3-N ha(-1) when 250 kg N ha(-1) was applied. Across N treatments, residual soil NO3-N contents ranged from 30 to 105 kg NO3-N ha(-1) with irrigation and from 30 to 202 kg NO3-N ha(-1) without irrigation. Residual soil NO3-N content within the surface 0.30 m was related (R2 = 0.94) to the NO3-N content to a 0.90-m depth. Estimates of residual soil NO3-N content at the economically optimum nitrogen fertilizer application (Nop) ranged from 46 to 99 kg NO3-N ha(-1) under irrigated conditions and from 62 to 260 kg NO3-N ha(-1) under nonirrigated conditions, and were lower than the soil NO3-N content measured with 250 kg N ha(-1). We conclude that residual soil NO3-N after harvest can be maintained at a reasonable level (<70 kg NO3-N ha(-1)) when N fertilization is based on the economically optimum N application.
淋溶造成的氮素损失是一个主要问题，对于需要大量氮肥的作物而言尤其如此。我们评估了氮肥施用和灌溉对加拿大新不伦瑞克省圣约翰河上游流域马铃薯（Solanum tuberosum L.）收获后土壤残留硝酸盐的影响。1995年，在两个农场地点，对三种氮肥处理（0、100和250千克氮/公顷）的土壤硝酸盐含量进行了测量，测量深度达0.90米；在1996年和1997年这两年中，对四个地点的四种氮肥处理（0、50、100和250千克氮/公顷）进行了测量，测量深度同样达至0.90米，测量时分为有补充灌溉和无补充灌溉两种情况。未施肥对照地块的土壤残留硝态氮含量为33千克硝态氮/公顷，施用250千克氮/公顷时则增至160千克硝态氮/公顷。在所有氮肥处理中，有灌溉时土壤残留硝态氮含量范围为30至105千克硝态氮/公顷，无灌溉时为30至202千克硝态氮/公顷。地表0.30米内的土壤残留硝态氮含量与0.90米深度处的硝态氮含量相关（R2 = 0.94）。在经济最优氮肥施用量（Nop）下，灌溉条件下土壤残留硝态氮含量估计值范围为46至99千克硝态氮/公顷，非灌溉条件下为62至260千克硝态氮/公顷，且均低于施用250千克氮/公顷时测得的土壤硝态氮含量。我们得出结论，当基于经济最优施氮量施用氮肥时，收获后土壤残留硝态氮可维持在合理水平（<70千克硝态氮/公顷）。
