Phosphorus dynamics in conservationist agroecosystem maize-cattle of neotropical savanna

Abstract

Phosphorus is one of the limiting elements in acid soils, so the incorporation of strategies for its cycling within an agroecosystem is one of the key variables, in order to optimize agricultural production. The dynamics of phosphorus in a maize-livestock agroecosystem were evaluated under the types of forages introduced: Brachiaria dyctioneura (Bd), a grass and Centrosema macrocarpum (Cm), a legume, which in turn served as associated perennial coverages maize grown with direct sowing. The dynamics of this element are contrasted in the savanna of natural vegetation (SN). It determined the availability of this element in the soil (0-15 cm), as well as the total P content in the excreta of the cattle and in the green fraction of the vegetation during the dry season, after the harvest of the corn, when the cattle a grazing is introduced. We analyzed the bromatological quality of livestock and the daily gain of weight in livestock (GDP). Concentrations of total P in the plant biomass varied according to the quality of the pasture forage, being higher in the Cm. This significantly affected (p<0.01) the excreta P and the available P of the soil, which resulted in a higher GDP. In the savanna conditions, P cycling in the subsystems of soil-plant-animal, is more effective when a forage legume is used as Cm, since it favors the incorporation of P through the excreta and by the decomposition of his necromass.

Keywords

• Forraje
• relación suelo-planta-excretas
• coberturas
• nutrición vegetal.