Kinetics of mineralization of nitrogen in forest soil, 2: Effects of soil water content and pH on mineralization of soil nitrogen
1994
Toda, H. (Tokyo Univ. of Agriculture and Technology, Fuchu (Japan). Faculty of Agriculture)
The effects of soil water content and pH on the mineralization of soil nitrogen were studied using the soil from an established sugi (Cryptomeria japonica D. Don) stand. The soil samples were incubated in vitro at three temperatures (20, 25, and 30 degrees C) with soil water contents of 40, 60, 80%. The samples of soil water content of 60% were incubated with CaCO3 added at rates of 0, 600,1,800 mg.100g dried soil(-1). The pH of the standard treatment (soil water content of 60% and no added CaCO3) decreased at first. NO3-N production increased throughout incubation for the soil water contents of 60 and 80%, but the residual NH4-N of the standard treatment increased later. Nitrification was reduced in the 40% soil water content treatment. The addition of CaCO3 raised the pH values, increased the NO3-N production, and decreased the residual NH4-N. The annual mineralization curves for soil nitrogen were similar to the soil water contents of 60, 80,%, and the addition of CaCO3, treatments. The curve for the soil water content of 40% reached a plateau sooner than the other treatments, but the maximum was less. The effect of the soil water content and the Ph on the annual amount of soil nitrogen mineralized were small for a forest soil. The effect of soil drying appeared at a soil water content of 40%. Kinetics analyses using in vitro incubation must take precaution against soil drying
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