长期施肥条件下水稻土有机氮组分及矿化特性研究

Fractions of Organic Nitrogen and N Mineralization Characteristic Under Long Term Fertilization on Paddy Soil

为探明长期定位试验条件下不同施肥处理和地下水位对水稻土有机氮组分及其矿化特性的影响,采用Keeney和Bremer酸解法对土壤有机氮进行分组研究,并利用改进后的Warning淹水培养-间歇淋洗法研究水稻土有机氮矿化特性。结果表明,不同处理土壤酸解氮占全氮的61.2%～64.4%,其中酸解未知氮,氨基酸态氮,氨态氮和氨基糖态氮分别占全氮26.9%～34.0%,13.0%～18.0%,12.6%～14.3%和2.3%～4.7%。恒温淹水培养106d后,以酸解未知氮降幅最大,且酸解未知氮与土壤氮矿化势之间有显著的正相关关系(r=0.865*),表明酸解未知氮是土壤可矿化态氮的主要贡献者。有机肥处理土壤矿化氮累积量及氮矿化势显著高于化肥处理,表明长期施用有机肥是提高土壤供氮潜力的有效手段。此外,低水位土壤矿化氮累积量及氮矿化势略高于高水位土壤。

In order to investigate the effects to long-term fertilization and underground water level on fractions of organic N and N mineralization characteristic in paddy soil,acid hydrolysis-distillation method proposed by Keeney and Bremer was adopted to investigate the fractions of organic N,and waterlogging incubation method proposed by Warning was used to investigate N mineralization characteristic.Results show that soil hydrolysable N accounted for 61.2%~64.4% of total N among different treatments,in which hydrolysable unidentified N,amino acid N,ammonium N and amino sugar N were 26.9%~34.0%,13.0%~18.0%,12.6%~14.3% and 2.3%~4.7% of total N,respectively.At 106 days after waterlogging incubation with constant temperature,the degree decrease of hydrolysable unidentified N was the largest,and there was significantly positive correlation between hydrolysable unidentified N and the potentially mineralizable N（r=0.865＊）,indicating that the unidentified hydrolysable N was the major contributor to the mineralized N in soil.Soil accumulation mineralized N and potentially mineralizable N in organic manure treatments were significantly higher than those of chemical fertilizer treatment,indicating that long-term application of organic manure was the effective method to enhance mineralizable N potential.In addition,the accumulation mineralized N and the potentially mineralizable N in soil with low water level was slightly higher than those with high water level.