Effects of temperature and water condition on soil nitrogen mineralization of different layers in Eum-Orthic Anthrosols of sub-humid area

Aerobic incubation experiment was conducted with Eum-Orthic Anthrosols(Cinnamon soils)of sub-humid area to study the effects of temperature and water condition on soil N mineralization of 090 cm soil layer which was divided into three layers(each 30 cm thick).Soil samples were incubated at different temperature of 8.0,16.0,24.0,32.0,40.0℃ in tubers,and water contents were adjusted to 11.0%,15.0%,19.0%,23.0%,27.0%(w/w),sampling 7,14,21,35,49,63, 84 days after incubation,respectively.The results showed that N mineralization accumulation quantity of all soil layers increased with the increase of temperature and water content,in the order of 030 cm3060 cm6090 cm.Mineralizable N of the 030 cm soil layer was the major part,which accounted for 67.9% of total amount in 090 cm soil layer.Every soil layer had different mineralization process: mineralization process of 030 cm soil layer could be described with linear equation and 3060 cm and 6090 cm soil layers with logarithm equation during incubation.Statistical analysis significant correlation was obtained between the soil N mineralization rate(k) and water content(w),which correlation coefficient was above 0.93.It was found that soil N mineralization rate of 030 cm soil layer was most sensitive to temperature,3060 cm was less,and 6090 cm was least.As a whole,under the condition of higher incubation temperature,the N mineralization rate would be shower with the increase of temperature and soil layer depth. Temperature and water content of soil had interactive effects on the quantity and rate of N mineralization.To 030 cm soil layer,the positive effect of moisture on N mineralization was more evident than temperature under the higher incubation temperature,while to 3060 cm and 6090 cm,the effect of temperature was more evident.