影响土壤尿素水解速率的一些因子

应用培养试验，以２种红油土为供试土样，研究了温度、水分、土壤前处理、加入葡萄糖或脲酶对尿素水解速率的影响；以２种红油土、１种黄绵土、１种黑垆土和１种黄褐土为供试土样，研究了土壤性质对尿素水解速率的影响。结果表明，温度对尿素水解速率的影响明显而突出，在５～３５℃范围内，温度系数（Q10）平均为１．７３，半水解期随温度升高而递减；土壤含水量在２０％～３０％时，水解速率基本稳定，但降至１５％时减少，风干后显著下降。土壤中分别加入葡萄糖和脲酶后会使水解速率增加，但前者持续时间长，后者持续短。尿素水解速率与土壤有机质和起始尿素浓度间有显著或极显著正相关，相关系数分别达０．９３*和０．９５*。

SOME FACTORS AFFECTING UREA HYDROLYSISRATES IN SOILS

With incubation experiments, 2 manural loessial soil were used to study the effects of temperature, moisture, soil pretreatment, glucose and urease on the rate of urea hydrolysis in soil; 1 dark loessial soil, 1 loessial soil ,2 manural loessial soil and 1 yellow cinnamon soil were used to study the effects of original urea concentration on the rate of urea hydrolysis; and 2 manural loessial soil, 1 dark loessial soil, 1 loessial and 1 yellow cinnamon soil were used to study the effects of soil properties on the rate of urea hydrolyses. The results showed that the temperature ranged from 5 to 35 has obvious effect on urea hydroysis rate and the average temperature coefficient (Q₁₀) is 1.73, the time in hour reguired to hydrolyse half the applied urea-N decrease with the raising of temperature. Althorgh the urea hydrolysis rates are stable at 20%30% of soil water content, the hydrolysis rates decrease apparently at the 15%, and rapidly decline after air-drying soil. Adding glucose and urease respectively, the urea hydrolysis rate increase pointedly, but the former treatment lasts longer period and the latter one quickly drops to previous level. Highly significant correlation is found between the urea hydrolysis rate and the organic carbon (correlation coefficient r is 0.93^*) and original urea concentration (r 0.95^{* *}).