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土壤水分含量是影响氮肥氨挥发的重要因素,关于尿素(U)或尿素—硝酸铵(UAN)溶液的氨挥发与水分蒸发之间的关系以及这两个过程的动力学信息尚不多见。我们测定了St.Bernad土壤(壤质、混合矿物型、非酸性、寒冷型的弱发育湿润软土)以及Ste.Sophie土壤(沙质、混合矿物型、非酸性、寒冷型的弱发育湿润软土)表施U和UAN溶液的氨挥发量。土样水势为<-1.5到0.01MPa,使用通气培育装置测定。结果表明,氨挥发量随土壤含水量的增加而增加,湿润(>-0.038MPa)和风干土样(<-1.5MPa)之间的挥发量差异随土壤粘粒含量的增加而缩小。然而,当土壤风干时,粘粒含量对氨挥发量的影响变得更加显著。水分蒸发与一级动力学反应一致,而NH_3挥发符合两个一级动力学反应,在-0.01MPa水势和70%相对湿度下,U溶液的氨挥发量(0.0338——0.348天~(-1))的初始速率常数(K_1)总是高于水分蒸发(0.099—0.104天~(-1))的初始速率常数。这种差异归因于对能量的需求不同,氨挥发与水分蒸发二者呈对数关系。
Soil moisture content is an important factor affecting the ammonia volatilization of nitrogenous fertilizer. The relationship between ammonia volatilization and water evaporation of urea (U) or urea-ammonium nitrate (UAN) solution and the kinetic information of these two processes are not yet known. We measured the activity of St.Bernad soils (loamy, mixed mineral, non-acidic, cold-type weakly developed moist soft soil) and Ste.Sophie soil (sandy, mixed mineral, non-acidic, Soil) surface U and UAN solution ammonia volatilization. Soil water potential is <-1.5 to 0.01 MPa, measured using aeration incubator. The results showed that the amount of ammonia volatilization increased with the increase of soil water content. The difference of volatile content between wet (> -0.038MPa) and dry soil samples (<-1.5MPa) decreased with the increase of soil clay content. However, the effect of clay content on ammonia volatilization becomes more pronounced when the soil dries. The evaporation of water is consistent with the first-order kinetic reaction, while NH 3 volatilization accords with two first-order kinetic reactions. The ammonia volatilization of U solution (0.0338--0.348 days ~ (-1) at -0.01MPa and 70% RH) )) Is always higher than the initial rate constant of water evaporation (0.099-0.104 days -1). This difference is due to the different energy requirements, ammonia volatilization and moisture evaporation are logarithmic relationship between the two.