Soil and available phosphorus losses in ecological olive groves.

摘要

Plant cover (PC) modifies water infiltration, altering runoff and sediment production, as well as the loss of chemical elements in surface runoff, in comparison to conventional tillage (CT). To determine the efficiency of plant cover in ecological olive groves in reducing extractable P loss, a study was established in three experimental fields located in the province of Cordoba (Andalusia, Spain), classified as Calcic Haploxerept (fields A1 and A2) and Ruptic Xerorthent (field A3). Soil, runoff and available P losses were analysed from 1 June 2003 to 1 June 2005. Plant cover significantly reduced available P losses in the experimental fields (by 41% in field A1, 78% in field A2 and 95% in field A3), soil losses (56% in A1, 80% in A2 and 81% in A3), and runoff (18% in A1, 55% in A2 and 45% in A3), with total rainfall of 689, 834 and 1016 mm in A1, A2 and A3, respectively. The cover percentage influenced available P loss as values of over 30% reduced it significantly in all the fields. Simple and multiple regression models were used to relate the available P loss to soil loss, runoff and the soil loss-runoff interaction. The selectivity of the erosion process was supported by values of the P enrichment ratio of between 2.3 in field A2 and 9.6 in field A3..