The Use of Straw Mulch in Mediterranean Vineyards to Reduce the Soil Losses.

Soil erosion in vineyards is not sustainable due to bare soils, low organic matter content, weak aggregates, sloping terrain and a millennia-old tradition of ploughing. To reduce soil erosion in vineyards, an increase of the vegetation cover is needed, but due to the farmers tradition to keep the soil clean all suggestions to use weeds and catch-crops got negative replies. A survey carried out  in the Terres dels Alforins district showed that 89% of the farmers rejected the use of weeds as a cover, 78% the use of catch crops, 56% the use chipped branches and 95% the use of geotextiles. However, only 45% of the farmers rejected the application of straw mulch. Upon this we developed measurements and experiments to determine the impact of the straw mulch cover on soil erosion. Eight plots of 1 x 2m (2m²) were constructed in vineyard Celler del Roure in Eastern Spain. Runoff, sediment concentration, vegetation cover, straw cover and rock fragment cover were monitored from 2010 to 2015 in 4 straw mulch covered plots and 4 bare plots. The results showed that the soil erosion rates reduced from 9.54 Mg ha^-1- y^-1 in the bare plot to 0.74 Mg ha^-1 y^-1 in the plots covered with straw mulch. The reduction of soil erosion started immediately after the straw mulch application and sustained for six years with 75 g of straw mulch per m². The runoff initiation took place after 8.5mm in the bare plot, and 15.9mm in the straw covered plot. Sediment concentration was on average, 6.65 times high in the bare plot, and the total runoff was on average 26 % higher in the bare plot.

Acknowledgements

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 603498 (RECARE project).