Organic Cereal/Forage Legume Rotation in a Mediterranean Calcareous Soil: Implications for Soil Parameters

摘要

In this study, we examined the effect of five years of organic farming on soil parameters of a dryland Mediterranean agroecosys-tem. The study involved a four-course rotation: barley I common vetch/oats/bitter vetch, with incorporation of crop residues into the soil, no fertilization, shallow tillage, and variable sowing practice. The overall effect of the organic rotation was to significantly affect soil organic matter (SOM), total nitrogen (N), and available phosphorus and potassium, even if theseeffects were inconsistent over the five years studied. Nevertheless, the overall effect of each crop in the rotation was to increase these soil quality parameters by comparison with the original values during the period of conventional cultivation. Giventhat SOM and total N content are key indexes of soil management sustainability, the principal finding was the positive effect of the rotation on them. Variable sowing had little influence on SOM, and had no effect on the other variables.