Short-term soil chemistry changes in a fire-free land use system for smallholdings in Brazilian Amazon

摘要

The aim of this study was to evaluate short-term effects of a low input fire-free system for land use by smallholders in Brazilian Amazon. Changes in soil pH, organic matter and extractable nutrients were evaluated during the first and second croppingperiods after lime and three fertilizer level application while using corn intercropped with rice and cowpea. During the first cropping period, lime application combined with fertilization resulted in higher soil pH in comparison with no lime and no fertilization treatments. In the second cropping period, larger value for soil pH was only observed if lime was combined with the higher fertilizer level. No lime application resulted in the decrease of soil pH, mainly when plants received fertilizer. Differences for soil organic matter were only observed during the second cropping period and the combination between liming and fertilization increased organic matter content. Both soil calcium and magnesium contents increased due to the association between liming and fertilization, while soil P was slightly increased because of fertilization. With the use of lime and the specific fertilizer levels, the soil chemistry of the fire-free land system did improve, indicating that the proposed system is suitable for smallholders in the Brazilian Amazon.