水热耦合作用下尿素转化为铵态氮的动力学模型

The dynamic model of urea transforming into ammonium affected by interaction of temperature and water

在4种温度、5种土壤含水量共20种处理的室内控制条件下,研究了土壤含水量、温度及其耦合作用与尿素转化为铵态氮的关系,探讨水热耦合作用下尿素转化为铵态氮的动力学过程,以及旱地农田尿素利用率。研究结果看出,在本试验条件下,提高土壤温度和土壤含水量均可以促进尿素向铵态氮的转化,且在尿素转化为铵态氮的过程中,土壤温度和土壤含水量存在着交互效应。同时建立了土壤中尿素转化中铵态氮含量变化的动力学模型(Y=a+bt+c／t),模型分析表明,土壤温度和水分对a值存在负交互效应,而对b、c值却存在正交互效应。此外,通过对试验各温区比温值的分析,发现施用尿素后铵态氮产生的最敏感温区及最敏感湿度,并针对施肥方法提出了一些建议。

The relation of the soil water content, the soil temperature and their interaction to urea transforming into ammonium with 4 grades of soil temperature (15, 20, 25 and 30℃) and 5 grades of the soil water content (40, 60, 80, 100 and 120g/kg) was studied in the room. The urea transformation was analyzed by determining the content of ammonium nitrogen in the different time with FIA. There were two aims for the study, the first was to make it clear that the dynamic process of urea transforming into ammonium affected by the interaction of soil water content and soil temperature and the second was to improve the utilization efficiency of urea in arid farmland. The results showed that the transformation efficiency of urea into ammonium was promoted, when the water content of soil or the temperature of soil increased. There was a highest content of ammonium in each treatment, which appeared on about the firth day to the tenth day. The highest content of ammonium increased when the soil water content and the soil temperature rose. The dynamic model that urea transformed into ammonium in soil could be expressed by the eolation as Y = a + bt + c/t (Y is the content of ammonium, t is time, a, b and c are coefficients) . The three coefficients all related to the soil temperature and water content. When the soil temperature unchanged, a and c increased with the soil water content, but b decreased. When the soil water content unchanged, a, b and c increased with the soil temperature. The interaction of the soil water content and the soil temperature was existed under this trial conditions. The effect of the interaction between the soil water content and the soil temperature on the a value was negative, and on the b and c values were positive. There were the optimum temperature and soil water content range for urea transformation into ammonium, respectively under the trial condition. The optimum temperature range was between 20 and 25℃, and optimum soil water content was 80g/kg.