Effect of Phosphorus Fertilization on the Chemical Composition of Lotus tenuis and Trifolium repens

One way of increasing forage yield and quality of natural pastures is through the inclusion of legumes in the grass cover. In order to achieve an appropriate crop establishment it is necessary to have an adequate availability of phosphorus (P) in the soil. Given the poor levels of this nutrient in many soils, it is necessary to fertilize. The objective of this study was to evaluate the effect of P fertilization at various doses on the content of P and nitrogen (N) in Lotus tenuis Waldst. & Kit ex. Willd. (lotus from the lowlands) and Trifolium repens L. (white clover) in a smectitic, fine, thermic Oxiaquic vertic argiudoll at Cerro Largo, Uruguay. The treatments were four phosphorus levels (0, 21,8, 43,6 and 65,4 kg P ha-1) broadcasted at seeding as triple superphosphate (0-46-0). The experimental design was randomized blocks, with eight repetitions. At 120 days post seeding, 10 plants/plot/specie were collected to determine the aerial part and root dry weight, and P and N content. P concentration in dry matter increased with P doses for both species, while N concentration showed significant differences only in T. repens.