长期定位施肥对土壤有机质、不同形态氮含量及作物产量的影响

Effects of Long-Term Located Fertilization on Soil Organic Matter, Nitrogen Forms and Crop Yields

通过长期定位试验,研究不同施肥处理对河北省低平原区土壤有机质、不同氮形态含量及作物产量的影响,旨在为该区冬小麦-夏玉米轮作系统秸秆全量还田下土壤肥力和作物产量的提高提供理论依据。结果表明,经过36个小麦玉米轮作周期的不同施肥处理后,与不施肥处理(CK)相比,施肥可以提高土壤有机质和全氮含量,且随化肥施用量的增加而逐渐增加。在化肥施用量≤N 360kg/hm^(2)+P_(2)O_(5) 240kg/hm^(2)时,秸秆还田较不还田可显著提高土壤有机质和全氮含量,在化肥施用量为N 540kg/hm^(2)+P_(2)O_(5) 360kg/hm^(2)时,增加速度减缓。与CK相比,长期施肥提高了土壤碱解氮和硝态氮含量,而对土壤铵态氮含量没有显著影响。单施化肥时,表层土壤碱解氮和硝态氮含量随氮肥施用量的增加而增加;在秸秆还田下,N360+P240+S9000处理表层土壤碱解氮和硝态氮含量最高。施肥显著提高了作物产量,单施化肥处理,小麦、玉米产量均随施肥量的增加而逐渐增加;秸秆还田条件下,小麦产量在化肥施用量≤N 360kg/hm^(2)+P_(2)O_(5) 240kg/hm^(2)时较单独施用化肥的处理增产。由以上结果可知,长期施肥可提高土壤肥力,增加土壤有机质和全氮含量,适宜的氮肥施用量配合秸秆还田可固持土壤有机碳和全氮,过量氮肥不利于土壤有机质的累积。长期单施化肥或化肥配合秸秆还田均可提高土壤碱解氮和硝态氮含量,对土壤铵态氮含量无显著影响。长期施肥可提高作物产量,在秸秆还田条件下,化肥施用量为N 360kg/hm^(2)+P_(2)O_(5) 240kg/hm^(2)时,增产效果较好。

To provide a basis for promoting soil fertility and increasing crop yield for winter wheat and summer maize rotation system under the straw returning in Hebei low plain, it is necessary to study the effects of long-term located fertilization test on soil organic matter, nitrogen forms, and crop yields. The results showed that after 36 wheat-maize rotation cycles of fertilizer experiment, compared with CK, the soil organic matter and total N and gradually increased with the increase of chemical fertilizer application. When the application of chemical fertilizer was less than or equal to N 360 kg/ha+P_(2)O_(5) 240 kg/ha, compared with no straw returning, the straw returning could significantly increase treatments of soil organic matter and total N, and the increasing rate was decreased under the treatment of N 540 kg/ha+P_(2)O_(5) 360 kg/ha. Compared with CK, long-term fertilization increased soil alkalihydrolyzable nitrogen(AHN) and NO_(3)^(-)-N contents, however, NH_(4)^(+)-N was not affected. The contents of soil AHN and NO_(3)^(-)-N increased with the increase of N fertilizer application with only chemical fertilizer treatments. Under straw returning, the contents of soil AHN and NO_(3)^(-)-N were the highest under the treatment of N360+P240+S9000. Fertilization significantly increased crop yield, with the single application of chemical fertilizers, the wheat and maize yields were increased gradually with the increase of fertilizer. When the application of chemical fertilizer was less than or equal to N 360 kg/ha + P_(2)O_(5) 240 kg/ha, compared with only chemical fertilizer, could increase wheat yield under the condition of straw returning. The long-term fertilization enhanced soil fertility and increased soil organic matter and total N, soil organic carbon and total N could be increased by suitable nitrogen application combined with straw returning, and excessive N fertilizer was not conducive to the accumulation of soil organic matter. Both long-term single application of chemical fertilizer and chemical fertilizer combined with straw returning could increase the contents of soil AHN and NO_(3)^(-)-N, but had no significant effect on the content of soil NH_(4)^(+)-N. And it also could increase crop yields. The effects of increasing yield of the application of chemical fertilizer(N 360 kg/ha+P_(2)O_(5) 240 kg/ha) was better than other fertilizering treatments.