Phosphorus fractions and soybean and bean yield in succession to grass fertilizer with different phosphorus source / FraÃÃes de fÃsforo e produÃÃo da soja e do feijoeiro em sucessÃo a gramÃneas adubadas com diferentes fertilizantes fosfatados

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The present work was intended to evaluate (1) the growth and P accumulation by cover forage grasses fertilized with triple superphosphate and reactive arad phosphate; (ii) the alteration of the soil phosphorus fractions after cultivation of the forage grasses and P accumulation by soybean and bean plant grown in succession to the grasses fertilized with triple superphosphate and reactive arad phosphate. Two experiments were undertaken, one under a Cambissolo HÃplico tb distrÃfico tÃpico, medium texture and the others under Latossolo Vermelho distrÃfico tÃpico very clayey texture. The experiments were performed in two steps. In the first step, the forage grasses were grown in pots with two phosphorus fertilizers. In the second step, after the cutting of the forages and deposition of straw on the surface of the pots, both soybean and bean plant were cultivated. For the evaluation of P accumulation and forage plantsâ growth, the completely randomized design was utilized in a 2 x 4 factorial scheme, four being forage plants (Brachiaria decumbens, Brachiaria brizanta, millet and forage sorghum) and two sources of P (triple superphosphate âSFT and Reactive Arad phosphate - FRA). For evaluation of P accumulation in grains and shoot, growth and yield of soybean and bean plant, the design utilized was that completely randomized in a 4 x 2 + 2 factorial scheme, the four treatments of soil cover being represented by the previous cultivation of the four forage plants (Brachiaria decumbens, Brachiaria brizanta, millet and forage sorghum) , two sources of P (SFT and FRA) and further two additional treatments. The additional treatments were represented by the two soils fertilized with the sources of P at the same time of the treatments with the cover grasses but that were not grown, remaining therefore, in fallow during the previous cultivation of the forage grasses. The results showed that in both soils the millet and sorghum presented hight growth and P accumulation when fertilized with SFT. The growth and P accumulation for the plants of the genus Brachiaria did not differ in function of the applied P source. Like this, when the forages were fertilized with FRA, the Brachiaria decumbens and Brachiaria brizantha presented larger relative efficiency of growth and P accumulation. For the fractions of P. the growing of cover forage plants with SFT provided greater accumulation of the fractions of inorganic and organic P, labile and little labile (P-resin, Pi-bic, Po-bic, Pi-hid and Po-hid). With the application of FRA after the growing of the forage plants, the highest contents of the fraction of Ca-linked P (P-HCL) and residual-P were obtained. The cover forage plants influenced the forms of P in soil as related with the potential of P accumulation in each plant and of the chemical and mineralogical characteristics of the soils. The forage plants immobilized the P of SFT, reducing its residual effect to soybean and bean plant. When the forage grasses are fertilized with FRA, there is a increase of the residual effect with increased soybean and bean yield in succession to cover plants with the exception of the growing of legumes in succession to Brachiaria brizantha.

ASSUNTO(S)

sorgo bean; soy bean; brachiaria dsecumbens; brachiaria brizantha; millet; forage sorghum; phosphorus fractions; phosphorus fertilizer ciencia do solo milheto braquiarÃo feijÃo fraÃÃes de fÃsforo braquiÃria soja adubaÃÃo fosfatada

ACESSO AO ARTIGO

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