Effects of the soil compaction on root growth of cover crops in the western Amazon

Abstract

The intensification of agriculture has increased the traffic of heavy machines, which can cause soil compaction, becoming a limiting factor for plant growth and development. The aim of this work was to evaluate the effects of machine traffic on soil physical attributes, root growth and dry mass production of legumes and grasses cultivated as cover. The experiment was carried in Rolim de Moura (RO). The experimental design was randomized blocks, in a split-plot scheme, with three replications. The treatments in the plots consisted of four induced soil compaction states: 0, 1, 4, 7 passes of an agricultural tractor, and in the subplots four cover crops species: Crotalaria, Stylosanthes, Millet and Palisadegrass. After two days of intense rainfall, compaction was carried out by passing the wheelsets of a New Holland-TL85E agricultural tractor, with 88hp of power, 4x2 TDA, standard tires 7.5x16 and 18.4x34, with blowing pressure of 110 kPa and 124 kPa, with a total mass of 3.16 Mg. Density, microporosity, macroporosity and total porosity were evaluated, surface area, root length and diameter and dry mass were also evaluated. During the period of full flowering of each crop, trenches were opened in each subplot for root evaluation and deformed soil and shoot dry mass samples were collected for evaluation. Significant discrepancies were observed for the physical attributes evaluated, surface area, length and root diameter of grasses in relation to legumes. After a tractor pass, there is an increase in soil density, and reductions in macroporosity and total porosity.