Estoques de carbono orgânico do solo em cafezais sob diferentes sistemas de controle de plantas invasoras

Abstract

Soil organic carbon (SOC) is an important indicator of soil quality, as its levels and stocks can change by soil preparation. This study aimed to evaluate SOC stocks on a clayey Oxisol cultivated with coffee and subject to different weed control systems in southern Minas Gerais, Brazil. The experimental design was in randomized blocks, and weed control systems were: no weeding, manual weeding, pre-emergence herbicide, post-emergence herbicide, rotary tiller, rotary mowers and disk harrow. Undisturbed soil samples were collected at two positions in the coffee plantation (tire tracks and planting line), at depths of 0-3, 10-13, and 25-28 cm. A nearby native forest was sampled as a reference. A higher bulk density of soils under coffee plantations occurred compared to soil under the forest. There was little difference between SOC concentrations in the plating line in relation to the native forest, but for the tire track position, the amount of SOC was generally lower. After correction for soil compaction, it was estimated a loss of ca. 20% in SOC stock for the 0-30 cm depth for herbicide post-emergence, rotary tiller, manual weeding and disk harrow, and a 35% loss when using herbicide pre-emergence. SOC stocks under no weeding and rotary mowers did not differ from native forest (37 M-1g ha SOC), indicating that the rotary mower, which allows temporary growth of weeds and does not disrupt soil structure, is the most appropriate weed control for the preservation of COS in coffee plantations.