Simulating soil conservation measures to control soil and nutrient losses in a small, vineyard dominated, basin

In recent decades, newly planted vineyards have been adapted for labor-saving mechanization. This has facilitated the use of machinery, but has meant that most of the soil and water conservation measures, which were assets in the original plantations, have had to be eliminated. This work analyses the effects of introducing drainage terraces and vegetative filter strips in a small basin (0.46 km2) whose main land use is vine cultivation. The basin is located in the municipality of Piera (Barcelona province, NE Spain). Soil and nutrient losses were simulated in scenarios with and without soil conservation measures, using SWAT, for years with different rainfall amounts and characteristics. The model was calibrated and validated using data collected in the basin during the period May 2010-December 2012. The annual rainfall during the study period ranged from 329.8 to 785 mm, with runoff rates of between 4.1 and 21% of total precipitation. In the scenario without conservation measures, annual soil losses ranged from less than 1 Mg ha−1, in the driest year, to 13.9 Mg ha−1, in the wettest. Average annual nutrient losses were around 2.7 kg nitrate (N-NO3) ha−1, 17 kg organic nitrogen (OrgN) ha−1, 0.5 kg soluble phosphorus (SolP) ha−1 and 5.5 kg organic phosphorus (OrgP) ha−1. These results highlight the fact that soil and nutrient losses from vineyards contribute to non-point source pollution and also to economic losses for grape producers. The introduction of drainage terraces produced a reduction in soil losses of up to 20%. Introducing filter strips further reduced these soil losses by up to 57%, while nutrient losses were significantly reduced by the introduction of both measures.