施用氮肥对不同肥力红壤性水稻土硝化作用的影响

Nitrification in Red Paddy Soils Different in Soil Fertility Under N Fertilization

通过室内培养试验,研究了施用尿素、硫铵条件下不同肥力红壤性水稻土的硝化作用变化特征,以明确土壤肥力和施用氮肥对红壤性水稻土硝化作用的影响。结果表明,不施氮条件下,不同肥力红壤性水稻土硝化作用表现为高肥力土壤<低肥力土壤。施用尿素条件下红壤性水稻土硝化作用显著增强,120和360mg·kg-1施氮量下,高肥力土壤平均硝化速率分别比不施氮对照升高了75.8%和357.1%,而低肥力土壤则分别升高了52.0%和146.9%,硝化作用强度表现为:高肥力土壤>低肥力土壤,360mg·kg-1施氮量>120mg·kg-1施氮量。施用硫铵条件下红壤性水稻土硝化作用强度降低,120和360mg·kg-1施氮量下,高肥力土壤平均硝化速率分别比对照降低了41.8%和74.7%,低肥力土壤则分别降低了3.1%和65.3%,硝化作用表现为:低肥力土壤>高肥力土壤,120mg·kg-1施氮量>360mg·kg-1施氮量。

To better understand effects of soil fertility and N fertilization on nitrification in red paddy soil,an incubation experiment was carried out.The objective was to follow changes in nitrification in red paddy soils different in soil fertility and application of N fertilizer.Results show that without fertilizer-N application,nitrification in soils high in fertility was higher than that in those low in fertility.Application of urea significantly increased nitrification in the soils.When it was done at a rate of N 120 and N 360 mg·kg-1,on average the nitrification rate increased by 75.8% and 357.1% in soils high in fertility and by 52.0% and 146.9% in soils low in fertility,respectively,as compared to CK.In terms of nitrification intensity,the treatments followed the order：soil high in fertility soil low in fertility,and soils applied with N 360 mg·kg-1 of urea soils with N 120 mg·kg-1 of urea.However,nitrification in red paddy soils was decreased when ammonium sulphate was applied.When its application rate was N 120 and N 360 mg·kg-1,on average,the nitrification rate decreased by 41.8% and 74.7% in soils high in fertility and 3.1% and 65.3% in soils low in fertility,respectively.In terms of nitrification,the treatments applied with ammonium sulphate were in the order：soil low in fertility soil high in fertility,and soils applied with N 120 mg·kg-1 of ammonium sulphate soils with N 360 mg·kg-1 of the fertilizer.