Arrobas, MargaridaPereira, ErmelindaFerreira, Isabel Q.Rodrigues, M.A.2013-09-172013-09-172013Arrobas, Margarida; Pereira, Ermelinda; Ferreira, Isabel C.F.R.; Rodrigues, M.A. (2013). The effect of legume cover crops on soil phosphorus availability. In First Legume Society Conference 2013: A Legume Odyssey. Novi Sad, Serbiahttp://hdl.handle.net/10198/8781Legume can fix atmospheric N and sequester carbon. Some legumes are able to uptake sparingly soluble soil phosphorus. Additionally, all those effects may contribute to a beneficial increase in soil microbial activity. In this work three ground-cover treatments were imposed to an olive orchard located in NE Portugal: Natural vegetation (Nat veg); Natural vegetation fertilized with 60 kg N ha-1 yr-1 (Nat veg +N); and a mixture of self-reseeding annual legumes (Legumes). Three years after the establishment of the ground-cover treatments, soil samples were taken from the 0- 10 and 10-20 cm depths. Extractable soil P was determined by the Olsen and Egner-Riehm methods, the acid phosphatase activity accordingly to Tabatabai and Bremner and soil organic carbon by the Walkley-Black method. In the 0-10 cm soil layer, the acid phosphatase activity was significantly higher in the treatments Legumes and Nat veg+N (7.81 and 7.30 f-Lg p-Nitrophenol g-1 ) than in the Nat veg (4.73 f-Lg p-N g-1 ). Considering both soil layers, there was observed a significant linear relationship between oxidizable organic C and the acid phosphatase activity (R2=0.69). The P extracted by the Egner-Riehm method was better correlated \vith the acid phosphatase activity (R2=0.42) than P extracted by the Olsen method (R2=0.31) when all samples were taken into account. It seems that a similar effect of the legumes species on the add phosphate activity may be achieved with the natural vegetation if fertilized with N.engSoil phosphorusCover cropsLegumesOlea europaeconference object