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比较研究了3年定位试验后稻草还田和施N水平对红壤双季稻作系统土壤供N能力、水稻吸N特征和水稻生产的影响。结果表明:头年晚稻草秋季还田对来年早稻土壤NH4+-N和作物吸N量的提高具有促进作用,而早稻新鲜稻草还田使晚稻土壤NH4+-N和作物吸N量均略低于移走稻草处理。稻草还田处理3年后,土壤可矿化N与移走稻草处理相比提高了35.4%~53.9%,且水稻各生育期干物质生产量均高于移走稻草处理,稻谷增产率达4.0%~4.7%。施用N肥可以显著增加土壤NH4+-N和可矿化N含量,且随着N肥用量的增加,水稻植株的累积吸N量和系统生产力(地上干物质量和产量)均显著的增加,建议N(全年施N量185 kg hm-2)和习惯N(全年施N量265 kg hm-2)处理相对于无N处理的增产率分别为35.2%和45.3%,而N肥的吸收利用效率分别为27%和25%,农学产量效益分别为每公斤纯N增产谷粒12.7 kg和11.4 kg。
The effects of rice straw returning and nitrogen application on soil N supply capacity, rice N uptake and rice production in double cropping system of red soil were compared and studied after 3 years of location experiment. The results showed that the late fall of rice straw in the first year could promote the increase of soil NH4 + -N content and N uptake of crops in the next year, while the fresh straw incorporation in early rice improved soil NH4 + -N and N uptake in cropland slightly Take the straw treatment. After 3 years of straw returning to field, the mineralizable N in soil increased 35.4% -53.9% compared with the removal of straw, and the dry matter production of rice at all growth stages was higher than that of straw removal, and the yield of rice reached 4.0 % ~ 4.7%. Application of N fertilizer can significantly increase soil NH4 + -N and mineralizable N content, and with the increase of N fertilizer, the cumulative N uptake and system productivity (aboveground dry matter yield and yield) of rice plants increased significantly. It is suggested that N (Annual nitrogen application rate of 185 kg hm-2) and conventional N (annual nitrogen application rate of 265 kg hm-2) were 35.2% and 45.3%, respectively, compared with no N treatment, while the absorption and utilization of N fertilizer The efficiencies were 27% and 25% respectively. The agronomic yield benefits were 12.7 kg and 11.4 kg of grain yield per kg of pure N, respectively.