土壤肥力和灌水组合对小麦植株-土壤系统氮素平衡的影响

采用15N示踪技术，在池栽群体条件下，研究了三种土壤肥力和两种灌水量组合对冬小麦生产系统氮素平衡的影响，结果表明：（1）不同处理氮肥的当季吸收利用率变化在39.08%~53.08%，土壤残留率在21.80%~33.59%之间，损失率变化幅度为18.81%~34.62%，植株吸收积累氮素中的29.88%~47.55%来自肥料；证明，采用不同土壤肥力和灌水量组合来调控小麦生产系统的氮素平衡具有较大的空间。（2）随土壤肥力的提高，植株吸收的总氮和土壤氮量显著增加，但营养体滞留量增加，向子粒的分配比例减少；而对肥料氮的吸收量则表现为中肥>高肥>低肥；氮肥损失率表现为低肥>高肥>中肥，残留率无明显变化，说明土壤肥力达到本实验的中等水平后再继续提高，会给肥料氮的吸收利用带来不利影响，但可有效降低对肥料氮的依赖。（3）增加灌水量在不同土壤肥力条件下均可促进对总氮的吸收量，但对土壤氮吸收的促进作用远高于肥料氮，同时也提高了肥料氮的损失率、降低了土壤残留率和向子粒的分配率。（4）提高土壤肥力和增加灌水量均可提高小麦的经济产量、生物产量和土壤A值，降低收获指数；子粒蛋白质含量随肥力的提高而增加，随灌水的增加而下降。

Effects of Soil Fertility and Irrigation Quantity on Nitrogen Balance in Wheat-soil System

By the method of 15N tracing technique, combined three different soil fertility with two different irrigation quantity, the synthesis effect of nitrogen balance in wheat production was studied in cement-pool cultivation. The result showed that: (1) The absorption efficiency of nitrogen fertilizer varied from 39.08% to 53.08% in different treatment, N remained in soil ranged in 21.80%~33.59% and losses in 18.81%~34.62%. Above data showed that nitrogen balance in wheat production system could be regulated effectively in large scale with different combination of soil fertility and irrigation quantity. (2) The amount of total N accumulated in wheat plant and which derived from soil increased, but the proportion resorted in vegetative organs increased and the proportion distribution in grain decreased significantly with increase in soil fertility. The order of N amount derived from fertilizer respond to soil fertility was as follows: medium fertility >high fertility >low fertility, the loss efficiency was low fertility >high fertility >medium fertility and there were no significant difference in residue rate of N fertilizer. Based on above analysis, it could have negative effect on absorption efficiency of nitrogen fertilizer with soil fertility increased gradually after medium level achieved, but it could effectively reduce dependence on nitrogen fertilizer. (3) Irrigation quantity increasing could enhance the capacity to absorb nitrogen on different fertility, but the synergistic effect of irrigation on soil nitrogen uptake was more than fertilizer nitrogen uptake, it also increased loss efficiency of fertilizer nitrogen, decreased residue rate in soil and distribution rate in grain. (4) Economic yield, biological yield and soil A values increased and harvest index decreased with soil fertility enhanced and irrigation quantity increased, protein content of grain increased with soil fertility enhanced and decreased with irrigation quantity increased.