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脲与磷酸结合形成的脲-磷酸脲(UUN)可减少氨的挥发,但尚未在田间条件下进行广泛研究。本试验旨在于实验室和田间条件下评价UUP(34-17-0)的肥效。试验系在酸性砂质土上进行的,这是美国东南部广为分布的典型的老成土。在室内和田间均用鼓风法直接测定氨的挥发量,此外还比较UUP及其它6种氮肥对免耕制中籽实高粱产量的影响。室内测定结果表明:在裸地和复盖地土壤上,UUP的氨挥发量都很小;而脲的氨挥发率在裸地上为所施氮的15-32%,在复盖地上为所施氮的68-82%。田间直接测定结果表明:脲、UUP和硝酸铵(施肥量均为200公斤N/公顷)的氨挥发率分别为所施氮的19%、5%和2%。田间小区试验结果表明:作物对UUP的反应优于对硝酸铵和硝酸钙的反应。氨挥发率的减少看来是由于UUP的酸性部分的pH缓冲功能所致。因此,在免耕制中,UUP是一种施于非石灰性土壤土表的较好的氮肥。
The urea-urea phosphate (UUN) formed by the combination of urea and phosphoric acid reduces ammonia volatilization but has not been extensively studied in the field. This experiment aimed to evaluate the efficiency of UUP (34-17-0) under laboratory and field conditions. The test was conducted on acid sandy soil, a widely distributed, typical aged soil in the southeastern United States. The ammonia volatilization was determined directly by the blast method indoors and in the field. In addition, the effect of UUP and other six nitrogen fertilizers on the sorghum yield in no-tillage was also compared. The results of laboratory tests showed that the ammonia volatilization of UUP was very small on the bare soil and the topsoil, while the ammonia volatilization rate of urea was 15-32% of the applied nitrogen on the bare soil, 68-82% of nitrogen. Direct field measurements showed that the ammonia volatilization rates of urea, UUP and ammonium nitrate (both 200 kg N / ha) were 19%, 5% and 2%, respectively, of the applied nitrogen. Field plots showed that the response of crops to UUP was superior to that of ammonium nitrate and calcium nitrate. The reduction in ammonia volatilization appears to be due to the pH buffering function of the acidic portion of the UUP. Therefore, in no-till, UUP is a better nitrogen fertilizer applied to non-calcareous soil surface soil.