Adubação Fosfatada E Compactação Do Solo: Sistema Radicular Da Soja E Do Milho E Atributos Físicos Do Solo

Abstract

Associated with the benefits of the no-till system for the soil there may be the formation of a vertical gradient of fertility and a compacted layer caused by heavy farm machine traffic which may modify the root growth of crops The aim of this study was to evaluate the effect of rates and forms of phosphate fertilizer application and soil compaction by machine traffic on the physical properties and root system of soybeans and maize The study was conducted in Campo Novo do Parecis MT Brazil in a clayey Latossolo Vermelho-Amarelo distrófico (Oxisol) in a randomized block experimental design with three replications A 2 × 4 × 4 factorial arrangement was used consisting of two forms of phosphate fertilization (broadcast and in the furrow) four rates of P2O5 (0 50 100 and 150 kg ha- 1) and four levels of compaction (PT0 PT2 PT4 and PT8 - no-tillage with compaction induced by tractor traffic at zero two four and eight passes respectively) Machine traffic causes soil compaction in no-tillage increasing soil bulk density (Bd) and soil resistance to penetration (SRP) and reducing macroporosity and total porosity without effect from P fertilization The response of the species to the form of P fertilization was differentiated There was no significant influence on root growth in soybean but in maize broadcast fertilization provided for greater root area in the root zone in the 000-005 m layer and fertilization in the furrow led to smaller differences in root area between the layer The SRP values of 148 and 184 MPa (Us = 028 m3 m-3) and Bd values of 132 and 135 kg dm- 3 in the 005-010 and 010-020 m layers respectively resulted in a reduction of 19 and 27% in the average diameter of corn roots and an increase of 110 and 49% in the diameter of soybean roots