秸秆还田下晚播稻茬麦适宜施氮量研究

    Economical Nitrogen Application on Late Sowing Wheat With Rice Straw Returning Under Rice-Wheat Rotation

    • 摘要: 研究了前茬水稻秸秆全量还田条件下,不同施氮水平(0、90、180、270和360 kg·hm-2)对晚播小麦土壤矿质氮积累、秸秆氮释放、氮素平衡特征和产量的影响。结果表明,基肥施用提高了越冬期0~30 cm土壤矿质氮量,追施氮肥提高了开花期0~15 cm土壤矿质氮量。施氮量高于180 kg·hm-2时会造成小麦成熟后土壤矿质氮量的显著增加。氮平衡分析结果表明,小麦全生育期氮素净矿化量为48 kg·hm-2;随施氮水平的增加,秸秆氮释放量、植株氮积累量、土壤矿质氮残留量和氮表观损失量均随之增加;N90、N180、N270和N360处理氮表观损失率分别为27.9%、37.6%、43.2%和47.6%;N90处理损失量以播种至越冬期最高,其余处理均以开花至成熟期最高。适量增施氮肥有利于提高籽粒产量,但施氮量若超过180 kg·hm-2,增产效果则不显著。综合考虑,水稻秸秆全量还田条件下氮肥施用量为180 kg·hm-2有利于兼顾晚播小麦生产和生态效益。

       

      Abstract: The straw of preceding rice was returned to field totally,and winter wheat was sowed with five N rate treatments( 0,90,180,270 and 360 kg·hm-2 applied to investigate the mineral N accumulation,straw N release,N balance and grain yield of winter wheat. The results show that mineral N accumulation amount in 0- 30 cm soil layer at overwintering stage increased with basal N application rates,as increased with top dressing N application rates in 0- 15 cm soil layer at anthesis stage. Mineral N residual was significantly higher than before planting when nitrogen rate was applied higher than180 kg·hm-2 .The analysis on N balance further indicat that the soil net mineralization N was 48 kg·hm-2 the amount of straw N release,plant N uptake,mineral N residual and apparent N losses increased as nitrogen application rate increased. The N loss ratio of N90,N180,N270 and N360 treatment was 27. 9%,37. 6%,43. 2% and 47. 6%,respectively. The loss of N mainly occurred before overwintering stage in N90 treatment,while in other treatments it was found after anthesis. There was no significant increase in yield when nitrogen rate exceed 180 kg·hm-2 .Considering both the grain yield and ecological effect,we suggest that the proper amount of nitrogen application for late sowing wheat with total preceding rice straw returning is 180 kg·hm-2 in those growing areas similar to this experimental condition.

       

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