Dynamic of Phosphorus in Soils Fertilized with different Phosphorus Sources and Phosphorus Acquisition by Lotus Corniculatus

The dynamic of the reaction between a clayey and sandy soil and three P-sources differing in P-solubility was study in a greenhouse experiment were Lotus corniculatus was cultivated and harvested several times during 287 days. The absorbed P by the plants with time was interpreted by an equation representing the P already present, added P, extracted P and the retained P even after the extraction by a soil-P test. The dry yield and P uptake differed between soils and for each soil among P-sources. In the clayey soil there was little difference with time between the two water soluble P-sources, both dry yield and P uptake, but in the sandy soil P uptake was significantly higher for poultry litter compared with triple superphosphate. Dry yield and P uptake were lower for phosphate rock with respect to both water soluble P-sources. In the clayey soil P uptake from the three P-sources with was mainly interpreted by the decrease of both the extracted and retained P, whereas in the sandy soil and for phosphate rock addition P uptake was described by the decrease of the retained P meanwhile extracted P was constant with time. Native P had little influence in both soil for all P-sources.