施肥对华北高产区土壤NO_3^--N淋失与作物NO_3^--N含量及产量的影响

EFFECTS OF FERTILIZATION ON NITRATE LEACH IN SOIL PROFILE AND ACCUMULATION IN CROPS AND YIELD RESPONSE IN NORTH CHINA

利用 4a的平衡施肥定位试验 ,研究太行山山前平原高产区冬小麦、夏玉米轮作制度下施肥对潮褐土中硝态氮的分布、移动、积累、植株吸收以及作物产量的影响 .结果表明 ,土壤剖面中硝态氮含量与施肥量直接相关 ,过量施用氮肥使硝态氮在土壤中大量积累并向下层快速移动 ;氮磷对作物的养分供应存在着既相互促进又相互竞争的关系 ,施用适量磷肥可以促进小麦、玉米对氮素的吸收 ,提高作物产量 ,减少氮素在土壤中积累和淋失 ,但施磷量太高 ,由于氮磷之间的竞争作用 ,作物吸氮量反而下降 ,从而导致土壤中硝态氮的积累和淋失加剧 .施用钾肥抑制了土壤硝态氮积累 .促进了两季作物植株对氮素的吸收 .从减少土壤硝态氮积累和淋失的角度 ,提出该区合理的施肥配比为组合N2P2K2 ,即 ρA(N) =2 0 0kghm-2 ,ρA(P) =32 .5kghm-2 ,ρA(K) =15 0kghm-2 .图 6参

A four-year experiment was conducted in the meadow-cinnamon soil in the field and lysimeters of farmland on the foot of Mt. Taihang in North China to study the effects of fertilization on the distribution, dynamics and accumulation of nitrate in soil, nitrogen uptake by crops and the yields of winter wheat and summer maize that were rotated in this region. The results indicated: the nitrate content and its dynamics were directly correlated with the content of applied nitrogen, i.e, over applied nitrogen could easily lead to accumulation and leaching of nitrate in soil profile; the relationship between nitrogen and phosphorus was of both promotion and competition, i.e., proper application of phosphorus could improve nitrogen absorption by crops and reduce nitrate accumulation and leaching loss in root layers in soil. However, excessive appication of phosphorus could easily lead to nitrate accumulation and leaching loss in soil, especially in the lower layer of the soil. The competition between nitrogen and phosphorus was confined by the results of nitrate absorption by plants. Applying potassium remarkably reduced the nitrate accumulation and leaching loss in soil and improved the nitrogen uptake and yields of winter wheat and summer maize. Thus, the fertilizer contents and ratio of nitrogen, phosphorus and potassium are the key measures for reducing the nitrate accumulation and leaching loss in soil and improving crop yield in this area. The annual fertilization for winter wheat-summer maize were recommended as N2P2K2〔ρ A(N)=200 kg hm -2,ρ A(P)=32.5 kg hm -2,ρ A(K)=150 kg hm -2〕 in this region. Fig 6, Ref 13