温度和水分对华中地区菜地土壤氮素矿化的影响

为研究华中地区菜地土壤的矿化特征和矿化规律,拟定菜地土壤合理的氮肥施用量,本文以华中地区两种典型菜地土壤——黄棕壤和潮土为研究对象,利用室内连续培养试验研究了温度、水分对菜地土壤矿化的影响。结果表明,黄棕壤的矿化速率和氨化速率均随着温度的升高而升高;硝化速率在15%和25%含水量下随温度的升高而升高,而在35%含水量下随温度的升高而降低。潮土矿化速率在15%含水量时随温度的升高而升高,而在25%和35%含水量下随温度的升高先增加后减小;硝化速率在15%和35%含水量时随温度的升高而增加,25%含水量时随温度的升高先增加后降低;氨化作用随温度的升高而降低。黄棕壤的矿化量在含水量为25%、温度35℃时高达34.9 mg.kg 1;潮土的矿化量在含水量为25%、温度为25℃时最高,为63.9mg.kg 1。不同温度下潮土矿化量均大于黄棕壤。黄棕壤的氨化速率随含水量的增加而增加,硝化速率随含水量的增加而降低,矿化速率则在含水量25%时最大。潮土的氨化、硝化和矿化作用随水分变化不明显。本研究还发现,25%的含水量是黄棕壤微生物活性的水分临界点,潮土的水分临界点不明显。通过对土壤氮素的矿化速率与水分含量和温度之间的函数关系模拟发现,黄棕壤模拟效果好于潮土。

Influence of temperature and moisture on nitrogen mineralizationin vegetable fields of central China

The processes of nitrogen(N) mineralization was determined in order to establish reasonable N application in vegetable fields in central China.The study researched the influence of temperature and water on N mineralization in two typical vegetable soils(yellow-brown and fluvo-aquic soils) in an indoor cultivation experiment.The results indicated that mineralization and am-monification rates in yellow-brown soils increased with increasing temperature.While nitrification rate at 15% and 25% water con-tents increased with increasing temperature,it decreased with increasing temperature at 35% water content.At 15% water content,mineralization rate of fluvo-aquic soil increased with increasing temperature.At 25% and 35% water contents,however,mineraliza-tion rate initially increased and then decreased.Nitrification rate in fluvo-aquic soil increased with increasing temperature at 15% and 35% water content.At 25% water content,however,it initially increased then decreased.Ammonification rate generally decreased with increasing temperature.At 25% water content and 35 ℃,mineralization rate in yellow-brown soil was 34.9 mg?kg?1.Also at 25% water content and 25 ℃,mineralization in the same soil was 63.9 mg?kg?1.Under different temperature conditions,mineraliza-tion rate of fluvo-aquic soil was higher than that of yellow-brown soil.While ammonification rate of yellow-brown soil increased with increasing water content,the reverse was true for nitrification rate.The maximum mineralization rate was at 25% water content.Variations in ammonification,nitrification and mineralization rate with water content in fluvo-aquic soil were not so evident.It was noted that the critical moisture content for microbial activity in yellow-brown soil was 25%,and that in fluvo-aquic soil was not evi-dent.The functional relationship of nitrogen mineralization rate with water content and temperature condition in yellow-brown soil was more significant than that in fluvo-aquic soil.