土壤地力和长期施肥对潮土区小麦和玉米产量演变趋势的影响

为潮土区合理施肥管理提供依据，对32个长期定位点、24年（1987～2010）不施肥和化肥配施秸秆（农民常规施肥）处理的小麦和玉米产量及其与土壤地力和施肥量间的关系进行了分析。结果表明:潮土区土壤地力对小麦和玉米产量的平均贡献率分别为51.4%和54.0%，变异系数分别为39.0%和41.2%。不施肥处理小麦和玉米产量每年分别下降4.1 kg/hm2和96.6 kg/hm2；常规施肥处理的小麦和玉米每年分别增产61.5 kg/hm2和26.8 kg/hm2。施化肥量与作物增产量（常规施肥产量－不施肥产量）呈显著正相关。通过通径分析进一步证明，施氮量对小麦产量具有显著直接作用。同时，磷肥对提高小麦和玉米的产量具有重要作用。总之，在农民习惯耕作施肥管理水平下，潮土区不施肥处理的产量下降缓慢（含品种对产量的贡献），常规施肥区产量表现出缓慢增加的趋势。

Effect of soil fertility and long-term fertilizer application on the yields of wheat and maize in fluvo-aquic soil

Long-term trends of crop yields and soil fertility have been used as a means to evaluate the sustainability of intensive agriculture, soil management and fertilizer application. Effect of soil fertility and long-term fertilizer application on the tendency of wheat and maize yield was analyzed based on 24-year data (1987-2010) collected from 32 sites, two treatments (no-fertilizer and normal fertilizer, which means NPK with straw) of long-term experiment of Drab Fluvo-aquic soil. The results showed that the average contribution rate of soil fertility to wheat and maize yield was 51.4% and 54.0%, separately. And the coefficient of variation (CV) of the contribution rate was 39.0% in wheat season, and 41.2% in maize season. The yields of wheat and maize in no-fertilizer field decreased slowly at a rate of 4.1kg/hm2 and 96.6 kg/hm2 per year, separately. In normal fertilizer application field, the yields of wheat and maize increased at a rate of 61.5 kg/hm2 and 26.8 kg/hm2 per year, separately. There was significant positive relationships between the amount of fertilizer and yield increase (yield in fertilized treatment – yield in unfertilized treatment). Path analysis of the relationship between fertilizer, soil fertility and crop yield confirmed that N fertilizer amount had significant direct effect on wheat yield. Phosphate fertilizer also had an important effect on the wheat and maize yield. In conclusion, crop yield in Drab Fluvo-aquic soil decreased slowly under no fertilizer condition, increased slowly under fertilizer treatment.