Estimation of Soil Nitrogen Mineralization in Corn-Grown Fields Based on Mineralization Parameters

The applicability of a new method of estimation of soil nitrogen mineralization based on nitrogen mineralization parameters (NMP) was examined in concrete-framed fields. In eight plots in 1983 and four plots in 1984, corn (Zea mays L.) was cultivated. The fresh soil samples collected before sowing were incubated at three temperature levels, and three kinds of NMP (N₀, nitrogen mineralization potential; k, mineralization rate constant; E_a, apparent activation energy) were determined by the kinetic analysis of the nitrogen mineralization curves. The amount of mineralized nitrogen during a growing season was estimated based on NMP with adjustments for the field soil temperature. The uptake of nitrogen by corn from soil nitrogen was determined by the use of ¹⁵N labeled fertilizer. When the estimated amount of mineralized nitrogen was less than 130 kg/ha, this value agreed with the measured one. These findings indicate that the use of NMP was effective for the estimation of nitrogen mineralization under field conditions. To apply this method for a soil testing program, some problems still remain to be solved. The characteristics of NMP obtained are also discussed.