| Greenhouses were almost closed environment. Environmental problems in greenhouses began to emerge as vast use of nitrogen fertilizer and the low utilization rate of fertilizer and volatilization N not easier to go out than outside . Laboratory and field experiments in greenhouses were carried out to study :short-term changes of soils pH and volatilization of ammonia by fertilizing urea in different temperature; changes of soils pH and volatilization of ammonia by fertilizing different types of urea; nitrogen transformation and the availubility of Al, Mn, Cu, Zn, Ca elements by fertilizing general urea and mineral coated urea; variation of NH3, NO2, O3 in greenhouses by fertilizing urea in soil. The results were as follows:1 .In 3 types of soil by fertilizing urea , pH rose first, then fell. Volatilization of ammonia became greater, peak value appeared at the beginning, then fell; the order of ammonia volatilization intensity was alluvial vegetable garden soil > red vegetable garden soil > tea garden soil. With the raising of temperature, the urea hydrolysis rate became faster; ammonia volatilization intensity increased and peak value appeared in advance. The reason for this difference was related to soil factors such as pH, CEC, OM, urease activation and the factor-temperature outside.2. The research on changes of pH and ammonia volatilization by fertilizing 4 types of urea showed that the fallen rate of pH by fertilizing Germany slow-release urea was the slowest, at the fifth week the pH value in alluvial vegetable garden soil was 7.95, 7.12 in red vegetable garden soil, the amount of ammonia volatilization was the biggest, 352.70 mg/kg soil in alluvial vegetable garden soil, 292.22 mg/kg soil in red vegetable garden soil. The fallen rate of pH by fertilizing mineral coated urea was the fastest while the ammonia volatilization was the smallest, 110.95 mg/kg soil in alluvial vegetable garden soil, 71.34 mg/kg soil in red vegetable garden soil. Because there was inhibitor(DCD) in Germany slow-release urea, which controlled nitroreaction and the fallen velocity of pH was slow, the amount of ammonia volatilization was great. The mineral coated urea was coated ground phosphate rock and reduced nitrogen release, decreased ammonia volatilization and betterthan other urea.3. By the formula Y=atb simulating the relationship of ammonia volatilization and incubated days, in the first 9 days the velocity of ammonia volatilization by fertilizing mineral coated urea was slower than that by fertilizing general urea, then they were close to the same. In 2 weeks the amount of ammonia volatilization by fertilizing mineral coated urea, 108.85 mg/kg soil in alluvial vegetable garden soil, 70.04 mg/kg soil in red vegetable garden soil, was half of that by fertilizing general urea. After incubated 48 days, the concentrations of NH4+ and NO3- in soil were bigger by fertilizing mineral coated urea than that by fertilizing general urea, the total of NH4+-N and NO3- -N was over 90% by fertilizing mineral coated urea.4. By fertilizing urea in soil, the concentrations of 5 elements of Al , Mn, Cu, Zn, Ca with the pH raising were more and more lower, then with the pH dropping they were more and more higher. The pH influence on Al was the most important factor, when the value raising to over 7.00, the concentrations of exchangeable Al were much lower. The pH influence on Ca was not so considerable. By formula Y=ax2+bx+c simulating the relationship of concentrations of these elements and pH , in pH 4-8, concentrations of these elements were negatively correlated with soil pH.5. The concentrations of NH3, NO2 were increased by fertilizing urea in greenhouses, which were higher by fertilizing general urea than by fertilizing mineral coated urea. The highest concentration of NH3 was 42.36 g/m3, 41.95 g/m3of NO2, not beyond the A grade criterion of atmosphere environment. The concentrations of O3 were higher in greenhouses than out of greenhouses. The highest concentration of O3, 118.87 g/m3, very cl...
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