Adição de fosfato e de micorriza, e estabilidade de agregados em amostras de latossolos cultivados e não cultivados

Abstract

There is little information on the contribution of soil microorganisms on aggregate stability in Brazilian soils, although it is well known that crop residue and cropping, especially gramineae, can increase aggregate stability. This study attempted to evaluate the effect of earlier cropping, phosphate, inoculation, and brachiaria and soybean on the geometric mean diameter (GMD), particle flocculation index, root dry matter, and total hyphal length, in Dark- and Dusky- Red Latosol. Samples of both soils under crop and no crop condrtion were brought to the green house and received P fertilization and inoculation, and then, they were cultivated twice with brachiaria and soybean. The results showed that the soils that were previously cultivated had lower aggregate stability Gower GMD), and lower total hyphal length, whereas inoculation increased these parameters according to P level. Hierewasno effect of P fertilization on particle dispersion. Oppositely, P had an indirect benefit on aggregate stability by increasing total hyphal length and root dry matter.