有机无机肥配施对水稻氮素利用率与氮流失风险的影响

农田土壤–作物系统对畜禽粪便有一定的消纳作用,有机粪肥与无机氮肥配施是未来农业生产中进一步增加产量、减少化肥施用和保护环境的重要生产模式。本研究采用盆栽试验,分析在施用一定量有机粪肥基础上,不同无机氮肥用量对水稻产量、氮素利用率和氮流失风险的影响,探讨有机肥与无机氮肥的最优比例,为有机肥施用条件下稻田无机氮肥的合理施用提供科学依据。结果表明:与单施有机肥(M)相比,配施0.8倍的无机氮肥效果最佳,水稻产量、株高、分蘖数、籽粒吸氮量和氮肥利用率达最高。有机肥作底肥时,水稻生长前期田面水无机氮浓度随配施无机氮肥量的增加而增加,而后期配施无机氮肥各处理田面水氮素浓度则随着氮肥施用量的增加呈现先降低后升高趋势,其中,增施0.4倍、0.6倍和0.8倍无机氮肥时稻田田面水氮素浓度较单施有机肥处理分别降低17.5%、11.9%和9.3%,差异达显著水平(P0.05)。与单施无机氮肥处理(N)相比,同样以0.8倍无机氮肥+有机肥处理作物产量和氮肥利用率最高,田面水氮浓度降低了30.2%,差异达显著水平(P0.05)。综上,消纳有机肥基础上,在满足作物需氮量的前提下,无机氮肥与其配比为1︰1时,既可以提高水稻增产潜力,又降低稻田氮素流失风险和适当减少稻田无机氮肥施用量。

Effects of Combined Application of Organic Manure and Different Levels of Chemical Fertilizers on Nitrogen Use Efficiency and Nitrogen Loss Risk in Rice Growing System

Soil-crop system plays an important role in the consumption of livestock manure, and the combination of organic manure and inorganic fertilizer is an important agricultural mode in increasing crop production, reducing the application of chemical fertilizer and protecting environment in the future. A pot experiment was conducted to study the effects of different dosages of inorganic nitrogen fertilizer on rice yield, nitrogen utilization and nitrogen loss risk in order to explore the optimal proportion of organic fertilizer and inorganic fertilizer and to provide scientific basis for the rational application of inorganic nitrogen when organic fertilizer used as base fertilizer in paddy fields. The results showed that when organic fertilizer used as base fertilizer in paddy fields, compared to the treatment of single organic fertilizer, crop yield, plant height, tillering number, nitrogen absorption by grains and nitrogen use efficiency all reached the highest when 0.8 times of inorganic nitrogen fertilizer was applied. With the increased application of inorganic nitrogen, nitrogen concentration in surface water of rice fields increased at the early stage of rice growth but decreased and then increased in the later stage of rice. Compared to the treatment of single organic fertilizer, nitrogen concentration in surface water significantly decreased by 17.5%, 11.9% and 9.3%, respectively under the treatments with 0.4, 0.6 and 0.8 times of conventional inorganic N application. Compared with the treatment with single nitrogen application, rice yield and nitrogen use efficiency were the highest under 0.8N+M treatment, and in which nitrogen concentration in surface water decreased by 29.9%. Therefore, based on the consumption of organic fertilizer and meet nitrogen demand of crops, 1:1 of organic nitrogen to inorganic nitrogen can not only increase rice yield, but also reduce nitrogen loss risk and the application rate of nitrogen fertilizer in paddy field.