Melhoria dos indicadores físicos de um argissolo coeso por meio da aplicação de gesso e biomassa de leguminosas arbóreas.

Abstract

In humid tropics regions, a combination of factors related to soil rootability conditions contribute to reductions in nutrient use efficiencies. The aim of this work was evaluate the combined effects of the application of gypsum and mulch from leguminous trees on soil rootability in the root zone, root growth and phosphorus recovery efficiency in maize planted in a sandy loam soil prone to cohesion. The experiment was conducted in a randomised block design with four replications and the treatments: control, without residue and gypsum (C); leguminous residue (L); leguminous residue and 6 t/ha of gypsum (LG6); urea, 6 t/ha of gypsum (UG6); leguminous residue, urea and 6 t/ha of gypsum (LUG6); and leguminous residue, urea, and 12 t/ha of gypsum (LUG12). Gypsum plus leguminous residues can enhance the soil rootability when applied in tropical soils due to the combined effects of increased porosity and decreased penetration strength. These effects facilitate root growth in the deeper soil layers and promote phosphorus uptake. Application of crop residue increases the input and retention of calcium derived from the gypsum in the lower layers. The use of large amounts of gypsum with residue, despite a strong increase in phosphorus uptake by maize, did not result in a proportional increase in dry matter production. Given the small differences in calcium content between the treatments with 6 and 12 t/ha, parcelling the application of gypsum in combination with residue applications, rather than administering a single high dose, is recommended for tropical sandy loam soils with low cation retention capacitys