连续秸秆还田替代钾肥对作物产量及土壤钾素平衡的影响

Effect of continuous straw incorporation substitute for K-fertilizer on crop yield and soil potassium balance

为了探索油菜-水稻轮作体系中连续秸秆还田替代钾肥效果,试验研究了连续秸秆还田配施钾肥对油菜-水稻轮作体系中油菜和水稻产量、地上部钾素累积量、钾肥利用率、土壤钾素含量的影响,探讨了秸秆还田可替代化学钾肥的用量。结果表明:1)油菜季秸秆还田可以替代1/3~2/3的化学钾肥而油菜不减产,水稻季随着试验年限的增加,秸秆还田能够替代化学钾肥的量呈减少趋势。轮作周期上,秸秆还田可以替代1/3的化学钾肥而油菜和水稻的总产量不减少。2)与单施钾肥(NPK)处理相比,油菜季,秸秆替代钾肥(NP+1/3K+S、NP+2/3K+S)处理均显著提高了钾肥吸收利用率和偏生产力;水稻季,NP+2/3K+S处理显著提高了钾肥吸收利用率和偏生产力,同时NP+1/3K+S处理也显著提高了钾肥偏生产力。3)在3个轮作周期中,不施钾肥(NP)、单施钾肥(NPK)始终处于亏缺状态,而秸秆替代钾肥处理(NP+S、NP+1/3K+S、NP+2/3K+S)的土壤钾素虽然在第1个轮作周期时均处于亏缺状态,但随着秸秆还田年限增加,亏缺量逐渐减少,至第3个轮作周期时,土壤钾素均处于盈余状态。4)秸秆还田配施钾肥均不同程度增加了耕层土壤速效钾含量,减缓了耕层土壤缓效钾含量的下降。上述结果表明:油菜-水稻轮作区秸秆还田减施钾肥有利于弥补土壤钾素亏缺,对维持土壤钾素平衡有重要意义。

The effects of continuous straw returning to field and recommended potassium fertilizer on yields of rapeseed and rice,K uptake,K efficiency and soil potassium content were studied to explore the effect of continuous straw returning to replace potassium fertilizer under rice-rapeseed rotation system.The results show that:1)The rapeseed season returning straw can replace 1/3~2/3 of potash without reducing the yield of rapeseed.With the increase of trial years in rice season,the amount of straw returning which can replace chemical potassium fertilizer is decreasing.In the rotation cycle,straw returning can replace 1/3 of chemical potassium fertilizer without reducing the total yield of rapeseed and rice.2)Compared with NPK treatment,NP+1/3K+S and NP+2/3K+S treatment significantly increased potassium absorption efficiency and partial productivity in rapeseed season;The NP+2/3K+S treatment significantly improved potassium fertilizer absorption efficiency and partial productivity,while NP+1/3K+S treatment also significantly increased potassium fertilizer partial productivity in rice season.3)In the three rotation cycles,the soil potassium of no potassium fertilizer(NP)and single application potassium fertilizer(NPK)were always in a deficit state.Although the soil potassium of straw replacement potassium fertilizer treatment(NP,NP+1/3K+S,NP+2/3K+S)was in a deficit state during the first rotation cycle,the deficit decreased gradually with the straw returning to field.By the third rotation cycle,the soil potassium was in surplus state.4)The treatments of straw returning with potassium fertilizer increased the available potassium content in the plough layer and slowed down the decline of potassium content in the plough layer.It indicates that straw returning with potassium fertilizer is beneficial to reduce the soil potassium deficiency,which is of great significance for maintaining soil potassium balance.