长期不同施肥下水稻产量及土壤有机质和氮素养分的变化特征

利用开始于1982年的湖南祁阳官山坪水稻长期(1982-2010年)定位试验，研究不同施肥条件下水稻产量及土壤有机质、氮素养分的动态变化特征，试验设置NPK、NPKM(M为牛粪)、 NPM、NKM、PKM、M和CK等7个处理.28年长期不同施肥处理结果表明：肥料的施用均能提高土壤有机质、全氮、碱解氮含量和水稻产量.氮、磷、钾化肥+有机肥(NPKM)处理的水稻产量一直保持最高水平，氮、磷、钾化肥(NPK)处理随着试验年限的延长呈下降趋势，其水稻产量逐渐低于其他施肥处理.单施有机肥或有机无机肥配施各处理土壤有机质含量在试验开始后的前16年有一个快速增加的过程，之后略有下降，然后仍保持增长趋势；NPK化肥处理土壤有机质含量仅在试验开始后的前8年增加较快，之后在一个相对稳定的范围内波动.各施肥处理在试验开始后的前8年内土壤全氮含量均呈快速积累趋势，以NPKM处理增幅最大.各施肥处理土壤碱解氮含量在试验开始后的前12年增加较慢，平均每年增加0.66～2.25 mg·kg^-1，1994-1998年增加较快，平均每年增加6.45～32.45 mg·kg^-1；1998年之后，各施肥处理土壤碱解氮含量均略有下降，其中，有机无机肥配施处理增加较快，单施化肥处理增加较慢.表明有机肥的施用是红壤性水稻土有机质和氮素营养水平稳定提升的关键措施，是红壤稻田土壤可持续利用的重要保障.

Change characteristics of rice yield and soil organic matter and nitrogen contents under various long-term fertilization regimes

A long-term (1982-2010) field experiment was conducted in the Red Soil Experiment Station of Chinese Academy of Agricultural Sciences in Qiyang County of Hunan Province, South-central China to investigate the dynamic changes of rice yield and soil organic matter (OM) and nitrogen contents under different fertilization treatments. The treatments included NPK, NPKM (M: manure), NPM, NKM, PKM, M, and CK. Fertilization increased the soil OM, total N, and alkaline-hydrolysable N contents and the rice yield. In treatment NPKM, the rice yield across the 28 years maintained at the highest level; while in treatment NPK, the yield showed a decreasing trend, being lower than that in other fertilization treatments. In the treatments applied with manure only or in combining with chemical fertilizers, the soil OM content increased rapidly in the first 16 years, and then fluctuated around a constant level (29.42-39.32 g·kg^-1). In the treatments of chemical fertilization, the soil OM content only had a quicker increase in the first 8 years, and then fluctuated within a relatively stable range. Fertilization with manure increased the soil OM significantly, as compared to fertilization with chemical fertilizers only. The soil total N content in all fertilization treatments showed a rapid increase in the first 8 years, and the increment was the highest in treatment NPKM. The soil alkaline hydrolysable N content in all fertilization treatments had a slower increase in the first 12 years, with an average annual increment of 0.66-2.25 mg·kg^-1·a^-1. In 1994-1998, the soil alkaline hydrolysable N content in fertilization treatments had a quicker increase, with an average annual increment of 6.45-32.45 mg·kg^-1·a^-1; but after 1998, the soil alkaline hydrolysable N content had a slight decrease. It was concluded that organic fertilization was the key measure to stably improve the physical and chemical properties and the productivity of red paddy soils by increasing their OM and nitrogen contents, and to sustain the rice production in red soil region in subtropical China.