红壤稻田不同施肥制度对土壤钾平衡和水稻产量的影响

基于14年田间定位试验,研究了红壤稻田系统在不同化肥配施条件下,有机养分循环利用对土壤K素平衡和水稻产量的影响。结果表明:不施肥或仅施化肥,土壤K素严重亏缺,其中以不施K的NP处理最严重,平均每年亏损K120.1kg/hm2,有机物养分循环利用的施肥制度可大幅度降低稻田土壤K素的亏损甚至出现K素盈余,NP C处理平均每年亏损K素2.2kg/hm2,而NPK C处理平均每年盈余K素154.5kg/hm2,但过高的K输入可能导致K营养元素的大量流失,降低K肥资源利用效益并增加环境污染风险,实行有机物养分循环利用时应适当减少化肥K的施用量;在不同施肥基础上的有机物养分循环利用都能显著提高水稻产量,但“循环”增产率随化肥配施程度提高而降低,不施肥基础上有机物养分循环利用的稻谷增产率为56%,与NP配施后,有机物养分循环利用的增产率降至18.8%,而在NPK配施基础上有机物养分循环利用的增产率只有10.2%,处理NPK C2与处理NPK之间的稻谷产量却没有显著差异,可见有机养分循环利用可以代替化肥K的施用;有机养分循环利用降低了K内部利用效率(IKUE)值,大小顺序为NPK C

Effect of different modes of fertilizer application on soil potassium balance and rice yield

Based on fourteen years field experiment,the effect of mineral fertilizer and organic nutrient recycling(C) on soil K balance and rice yield was studied in the double-rice-cropping region of subtropical China.The results show that zero-fertilizer or only mineral fertilizer application makes the soil deficient in K.NP treatment shows grievous deficit with average K shortage of 120.1kg/hm2.Combined application of organic manure and NP or NPK reduces negative K balance effect and even results in an increased soil K release.For instance,treatment NP C has a negative K balance of 2.2kg/hm2 deficit per year,and treatment NPK C has a positive K balance of 154.5kg/hm2 surplus per year.However,exorbitant K input can lead to a great deal of K nutrient loss,which reduces K use efficiency and increases risk of environmental pollution.In comparison with mineral fertilizer,organic nutrient recycling improves rice yield significantly.But the rate of production increase by recycling decreases with increasing proportion of N,P and K.Based on zero-fertilizer rice production-increasing rate of organic nutrient recycling is 56%,and incorporation with organic nutrient recycling,NP and NPK yield production-increasing rates are 18.8% and 10.2%,respectively.Treatments NPK C2 and NPK have no significant difference in rice yield.It is obvious that organic nutrient recycling can substitute chemical potassium fertilizer.Organic nutrient recycling decreases internal potassium use efficiency by the given sequence:NPK C