摘要:土壤盐渍化造成氮素的损失，限制了作物对氮素的有效利用。为研究滨海盐渍化农田等氮量投入条件下，有机无机肥配施对农田土壤盐分和作物氮素养分吸收利用及氮平衡的影响，以江苏东台滩涂围垦农田为研究平台，选取玉米品种‘长江玉8号’为供试作物，设6个处理：不施肥（CK）、全有机肥（OM1）、1/4化肥+3/4有机肥（OM3/4）、1/2化肥+1/2有机肥（OM1/2）、3/4化肥+1/4有机肥（OM1/4）、全化肥（OM0）。在玉米播种前、生长期和收获后采集土样，同时在收获后采集植株样品，分析土壤盐分、pH、水分、无机氮含量和玉米植株不同部位的氮含量和累积量，计算氮肥利用效率和氮平衡。结果表明：1）有机肥代替部分化肥的施入，降低了滨海盐渍化农田土壤的电导率，且呈现出随有机肥施用量增加电导率逐渐降低的趋势，但其对土壤pH影响不显著。2）有机肥的施入提高了土壤有机质含量，改善了土壤结构，降低了土壤容重，同时提高了土壤含水率，增强了土壤的持水性能。3）就不同处理玉米产量和吸氮量来看，OM1/4处理玉米产量、籽粒含氮量和全植株吸氮量最高。同时，氮收获指数、氮肥当季回收率、氮肥农学效率和氮肥偏生产力等指标也较高。4）就氮素平衡状况来看，氮素输入量远大于作物吸收量和土壤残留量，有很大一部分无机氮损失掉。其中，OM1/4处理氮素表观损失量较小。综合有机无机肥配施对降低土壤盐分和作物养分吸收利用两者来看，在225 kg·hm-2氮用量条件下，OM1/4处理效果最好，既能在一定程度上降低土壤含盐量，又能维持较高的作物产量和氮素利用效率。同时对于改善土壤结构，提高土壤的保水性和土壤有机质含量都具有重要意义。
关键词:土壤盐渍化/
有机无机肥配施/
土壤盐分/
氮利用率/
氮平衡
Abstract:Salinization reduces soil N utilization and must be controlled. The objective of this study was to evaluate the effect of application of organic and inorganic fertilizers in various combinations on soil salt content and N utilization. A series of field experiments were conducted in newly reclaimed and salinized farmland in Dongtai, Jiangsu. Maize 'Changjiangyu 8' was grown in soils receiving no fertilization (CK) or applied with one of the following combinations of fertilizers:OM1 (manure only), OM3/4 (1/4 chemical fertilizer and 3/4 manure), OM1/2 (1/2 chemical fertilizer and 1/2 manure), OM1/4 (3/4 chemical fertilizer and 1/4 manure), and OM0 (chemical fertilizer only). All combinations provided 225 kg·hm-2 N. Soil samples were collected before sowing, during the growing stage of maize, and after maize was harvested. Samples were analyzed for salt content, pH, moisture, and inorganic N. Harvested maize plants were analyzed for N. Crop N uptake and soil N balance and use efficiency were computed. Application of manure increased soil porosity and reduced soil density and surface salt. As a result, the electric conductivity of the soil decreased, and the decrease appeared to be proportional to the rate of manure application. Soil pH was not affected. Application of manure increased soil moisture and organic matter content, and the increase was in proportion to the rate of manure application. Application of OM1/4 resulted in the highest corn N uptake, N content, and yield among all treatments. The combination was also highest in N harvest index, N recovery, N agronomy efficiency, and N partial productivity. While balance analysis showed loss of N from the soil for all treatments due to leaching, runoff, and volatilization, the loss was lowest for OM1/4. Application of combined 3/4 chemical fertilizer and 1/4 manure to provide 225 kg·hm-2 N reduced soil salinity and resulted in the highest corn production and N efficiency. Meanwhile, it also had significant influence on the improvement of soil water holding capacity, soil structure and organic matter content.
Key words:Soil salinization/
Organic and inorganic fertilizer combinations/
Soil salt/
Nitrogen use efficiency/
Soil nitrogen balance
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