Nitrogen mineralization from mature bio-waste compost in vineyard soils III Simulation of soil mineral-nitrogen dynamics

Abstract

A model for nitrogen (N) dynamics in compost-amended vineyard soils was tested for its predictive power. A soil-mineral N data set from a 3-year field study on four different vineyard sites was used for model evaluation. The soils were treated with mature bio-waste compost (30 and 50 Mg ha-1 fresh matter, respectively). The model calculated soil mineral-N contents at all sites with an overall mean bias error of -2.2 kg N ha-1 for layers of 0.1 m thickness and an overall mean absolute error of 7.4 kg N ha-1 layer-1. Modeling efficiencies for the simulations of the respective treatments ranged from -0.05 to 0.41, and Willmott's Index of Agreement showed values of between 0.41 and 0.81. Acceptable model predictions as defined by the observed variability of mineral-N contents in the respective soils ranged from 40% to 72%. A strong increase in soil mineral-N concentration following the compost application at all sites could not be reproduced with the model, thereby reducing the prediction accuracy significantly. The model performance confirms that previously derived N-mineralization parameters are suitable to describe the N release from soil-applied mature bio-waste compost under the environmental conditions of vineyards in Germany. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.