The weed management systems applied in coffee plantations can promote changes in soil structure that compromise the capacity of the soil to infiltrate, distribute, transmit and retain water, in function of pore-size distribution. The aim of this study was to verify the effect of applying different techniques of weed management on the pore system and water retention capacity in a Latosol (Oxisol) in the inter-rows of a coffee plantation. The area of study is located at the Epamig Experimental Farm (Latitude 20º55'00" S and Longitude 47º07'10" W) in São Sebastião do Paraíso, southern Minas Gerais. The weed managements evaluated were: without hoe (SCAP), manual hoe (CAPM), post-emergence herbicide (HPOS); mower (ROÇA), rotary tiller (ENRT), coffee tandem disk harrow (GRAD) and pre-emergence herbicide (HPRE). Undisturbed soil samples were collected randomly in the inter-rows of the coffee plants under different weed managements at 0-3, 10-13 and 25-28 cm depths, totaling 315 samples. In a native forest (MATA) adjacent to the LVdf in the study area, 15 additional samples were collected per depth, as reference for the attributes. Soil water retention curve, pore size distribution (macroporosity: pores with effective diameter greater than 50 mm and microporosity: pores with effective diameter smaller than 50 mm) and volumetric total porosity (VTP) were also assessed. The main alteration in soil structure was observed in soil water retention curve and pore size distribution at 0-3 cm depth. The extreme behaviors for all the physical-hydric attributes assessed were for the LVdf under MATA and the soil under coffee with GRAD and HPRE. The other management systems presented intermediate behavior for all the attributes. The use of the soil with coffee plants decreases volumetric total porosity and macroporosity at 0-3 and 10-13 cm depths, compared to native forest. There was no effect of the different weed management systems on volumetric total porosity, macro-porosity and micro-porosity at 25-28 cm depth of LVdf in relation to the soil under native forest.
soil compaction; soil structure; soil water retention curve; pore distribution per size; mechanical and chemical management methods
