Some Soil Factors Affecting Air Pollution by Ammonia Volatilization from Urea Fertilizer

摘要

AMMONIA volatilization from urea reduces nitrogen fertilizer efficiency of crops andvincreased air pollution. Some soil factors such as clay percent, calcium carbonate content, moisture regime and organic matter content were studied in two of laboratory incubation experiments under aerobic conditions at 20 ± 2 deg. Soil samples were collected from Qalubia Govemorate, Ismailia Govemorate and Alexandria Goyernorate which represented clay loam, sandy and calcareous soils, respectively. Ammonia volatilization losses from urea reached 14.4, 26.7 and 32.6% of the applied urea fertilizer to clay loam, sandy and calcareous soils, respectively. Whereas, ammonia volatilization increased as a result of increasing calcium carbonate content in the soil (calcareous soil) by about 2.3, and 1.2 times compared to clay loam and sandy soils, respectively. Moreover, the increases of ammonia volatilization from soil at 50% of water holding capacity were 38, 76 and 88 % relative to those found at 100 % water holding, capacity after three weeks of applied urea to the investigated soils, respectively. Also, application of cattle manure at rates of 2 and 5% decreased the amount of NH_3 volatilization from calcareous soil by about 43.1 and 53.6 % at full water holding capacity. The concentration of NH~+_4 in the soil solution increased due to application of urea fertilizer particularly when cattle manure and clay content were increased along with low water content in soil. Such increases recorded 57, 135 and 165% at theend of experiment (21 days) at low moisture in clay loam, sandy and calcareous soils, respectively. On the other hand, the values of nitrate concentration decreased with increasing water content in the different soils. So, the results showed that soil pH, water content and organic matter content are major factors influencing ammonia losses from soils compared with the other studied factors.