Moist soil

Nitrogen mineralization potential (N_0 ) and mineralization rate constant (k) are major parameters used to estimate soil mineralizable nitrogen during the rice growth period. These parameters are determined with soil incubation tests, which are laborious and time-consuming. Thus, simple estimation of N _0 and k are required to use the parameters for planning fertilizer applications. The objective of this study was to investigate correlations between N0 or k of moist paddy soils and soil physicochemical properties. First, N_0 and k were calculated using kinetic analysis for soils collected at 16 paddy fields in Itoshima city, Fukuoka Prefecture. Next, correlations were analyzed between N_0 or k and soil physicochemical properties including total nitrogen (TN), total carbon (TC), clay, silt, sand contents, and cation exchange capacity (CEC). TN and TC are simply measured with a CHN analyzer, while clay, silt, sand contents, and CEC can be referred over years when the properties are measured once. For the relationship with N_0 , TN showed a positive correlation (r =0.602) at 1% significance level. TC, clay content, and CEC showed positive correlations (r =0.569, 0.526, 0.431, respectively) at 5% significance level, while sand content showed a negative correlation (r = − 0.504) at 5% significance level. For the relationship with k, sand content showed a positive correlation (r =0.481) at 5% significance level, while silt content showed a negative correlation (r = − 0.460) at 5% significance level. The result implicated that the correlations between k and sand or silt content are significant only when the ranges of the values are large.