Linking Semiarid-Mountain Agriculture to Environmental Benefits and Adverse Impact

摘要

The soil erosion, runoff and nutrient-loss patterns were monitored in a mountainside with olive (Olea europaea cv. Picual) plantations under conventional and conservation agricultural systems based in two different soil management: 1) conventional tillage and 2) non-tillage with barley (Hordeum vulgare) strips of 4 m width, respectively. The erosion plots, located in Lanjaron on the southern flank of the Sierra Nevada Mountains in SE Spain, had 30% slope at an altitude of 565 m and 192 m2 (24 m x 8 m) in area. The highest erosion rate of 3.5 t ha"' was registered under conventional system and runoff of 11.4 mm under conservation system, over the entire study period (19 erosive events). The conservation system reduced the soil erosion by 69% with respect to the conventional system, and the runoff under conventional system in relation to conservation system by 54%. The total NPK fluxes by runoff from conventional system amounted to 2.87, 0.09 and 0.93 kg ha~(-1), and from conservation system 1.57, 0.09 and 0.98 kg ha~(-1), respectively. In general, the soluble average concentrations of plant nutrients (N-N0_3, N-NH_4, P H_2P0_4, and K) in the surface runoff were higher than the recommended level for standard water quality for from conventional system. These findings support the recommendation of conservation agricultural techniques for semiarid and sloped agricultural land with rainfed-tree crops for erosion and pollution control.