Characteristics of inorganic nitrogen in soil profile for continuous maize production in Northeast China | 东北春玉米连作体系土壤剖面无机氮的变化特征

Chinese. 研究不同施肥方式对东北春玉米生长及连作体系土壤中氮素含量的影响，为春玉米的合理施肥提供理论依据。2005-2006年，在东北中部黑土春玉米连作区进行2年的田间定点试验，研究了一次性施肥（农民习惯施肥1、农民习惯施肥2）和推荐施肥条件下，玉米不同生育阶段地上部生物量和吸氮量及土壤无机氮含量的变化特征，并对土壤氮素表观盈亏进行了估算。玉米地上部生物量和吸氮量均随施氮量的增加而增大，其中推荐施肥处理的生物量和吸氮量均最高。施氮显著增加了0~90 cm土层中的无机氮含量。2个习惯施肥处理土壤的硝态氮含量受降雨量的影响较大，且下移明显；推荐施肥处理可明显降低硝态氮在土壤中的残留。土壤氮素表观盈亏取决于氮肥用量，2006年农民习惯施肥1处理的土壤氮素表观盈余量最高，且多以残留硝态氮的形式累积在深层土壤中。在东北黑土春玉米连作区，氮肥一次性基施会导致土壤中的无机氮高残留，增加氮损失，易对该地区的生态环境造成威胁，本试验中的推荐施肥是较好的施肥方式。

English. The study was conducted to evaluate the effect of different nitrogen applications on the growth of spring maize and nitrogen content of soil environment for continuous maize production in Northeast China and to guide the fertilization application of spring maize. A two-year field experiment was conducted to understand the biomass and nitrogen accumulation, movement characteristics of inorganic nitrogen in soil at different growth stages and the apparent budget of soil nitrogen in the black soil for continuous maize production under one-time fertilizer (traditional application treatment 1 and 2) and optimized N treatment in Northeast China. The results indicated that the biomass and nitrogen accumulation of plant were increased with the nitrogen application rate. The biomass and nitrogen accumulation under optimized application treatment was highest. The inorganic nitrogen in soil layer (0-90 cm) was significantly increased with the increment of nitrogen application rate. Traditional application treatment 1 and 2 were influenced by annual rainfall amount. The residual nitrate moved down obviously. The nitrogen residue in the soil decreased significantly under optimized application treatment. The apparent budget of soil nitrogen was mainly up to the nitrogen fertilizer application rate. The soil nitrogen surplus was highest under traditional application treatment 1 in 2006. But the most leached into the deep soil layer. The single-dose application results in high residual in soil layer and increases nitrogen loss. It threatens the environment to a large degree. Basal fertilization plus optimized topdressing based on soil mineral-nitrogen test is a promising way.