SOIL EROSION IN CITRUS PLANTATIONS ON SLOPE. CANYOLES RIVER BASIN, VALENCIA.

Abstract

During the last decades the citrus orchards in the Mediterranean has moved from the lower topographical positions to the hillsides searching a free frost climatic areas. All this has been possible since the introduction of the drip-irrigation, promoted by the urban development pressure on the coastal land and valley bottoms, and fomented by the cost reduction in the groundwater pumping. The new plantations occupy now spaces of high slope angles where the losses of soil are high. In spite of the change in the location of the orchards -from plains to hillsides - the soils are being intensely ploughed or applying herbicides in order to eliminate the weeds. The conservation and organic farming agriculture can help to detain the high losses of soil. Experiments with simulated rainfall (60 mm h-1) in citrus fi elds on the Montesa’s valley (Valencia) where herbicides have been applied, on straw mulch and cash crops applied were carried out to quantify very different rates from erosion according to the applied management. The rate of erosion was negligible on the straw mulch and cash crops, meanwhile on the ploughed fi eld reached 10 g m-2 h-1, whereas in those with herbicides the loss of soil ranged between 37 and 58 g m-2 h-1.