Pruning Residues as an Alternative to Traditional Tillage to Reduce Erosion and Pollutant Dispersion in Olive Groves

During the seasons 2003/04, 2004/05 and 2005/06, a study was made of the evolution of runoff as well as soil and available P and K losses in the sediment carried away in a conventional till system—that most used at the present time—and in a no till system with added pruning remains in an olive grove of the picual variety located in Torredonjimeno (Jaén, Spain). A group of microplots for sediment collection in a randomized complete block design was established. The samples were collected in the field after each storm. In the study period, a total of 21 storms were recorded, with a precipitation of 450 mm in 2003/04, 179 mm in 2004/05 and 388 mm in 2005/06. The erosivity of the rainfall was characterized and the cover percentage in the plots throughout the time was determined. The establishment of pruning remains reduced soil loss with respect to conventional tillage (CT) in the 3 years (72%). Likewise, the available P loss greatly declined in the study (46.4%) under conservation agriculture. The reduction in available K loss (72.4%) was much greater than that of available P. The close relationship between both variables and sediment production also stands out. Runoff was the parameter on which the pruning remains had the least influence with only an 11% average reduction.