Prediction of Soil and Nutrient Losses on Chianti Vineyard with SWAT Model

Abstract

In Mediterranean area, hillside vineyards are frequently subjected to high soil losses due mainly to improper management techniques which influence the dynamics of nutrients. The aim of this study is to evaluate the Soil and Water Assessment Tool (SWAT) performance in predicting nitrogen and phosphorus content in runoff and soil particles transported from experimental fields. Runoff volume and composition was measured during several rainfall events (87), measured from January 2005 to December 2008, in instrumented up-down slope vineyard at the Montepaldi Farm - University of Florence, in Tuscany (Italy). Both harrowed and grassed inter-row management techniques were evaluated. SWAT was tested using a 10 min runoff model to simulate hydrology, then model results were compared with field observations. Notwithstanding the SWAT model overestimates the soil loss and the runoff, the results of this study show good agreement between simulated and measured data both for runoff and soil loss with Nash-Sutcliffe efficiency (NSE) values, both for harrowed and grassed plots higher 0.89. Moreover the SWAT model performed satisfactorily in simulating daily nitrogen and phosphorus losses, both on grassed and harrowed plots, with a NSE higher than 0.92 both for the calibration period and validation period.