Relationships between net nitrogen mineralization and soil characteristics within an arable field

Within-field variations in plant-available soil nitrogen are likely to be affected by differences in soil characteristics. To study this, a 3-year field investigation was conducted during 1998-2000 on a 15-ha arable field in Sweden with considerable within-field soil texture variability. In 34 plots soil nitrogen uptake by crops, net nitrogen mineralisation (Nm) during the growing season and soil mineral nitrogen in spring and shortly after harvest were determined. Beside these parameters, topography, soil organic matter content (SOM), clay content, pH(H2O) and grain yield were recorded. The variations in Nm were considerably large both within the field and between years. The within-field variation in Nm could partly be explained by the variation in SOM and clay content (r2adj = 0.23***). The pattern in Nm differed between years, partly due to seasonal variations in soil moisture. For these reasons, the pattern of Nm is difficult to predict without seasonal adjustments