Estoque de nutrientes sob diferentes sistemas de uso do solo de Colorado do Oeste-RO

Abstract

A substituição da floresta por outro tipo de uso do solo pode levar a perdas significativas na matéria orgânica do solo, alterando sua dinâmica e como consequência alterando as entradas e saídas de nutrientes do sistema. Neste trabalho o objetivo foi avaliar o estoque de nutrientes em diferentes sistemas de uso de solo em Colorado do Oeste-RO. Os sistemas avaliados foram o agroflorestal (teca e cacau), florestal (teca com cinco anos), teca com oito anos, agrossilvopastoril (teca, cacau e pasto) e pastagem tendo a mata nativa como referência. Em cada sistema foram abertas três minitrincheiras, nas quais foram coletadas amostras deformadas e indeformadas nas profundidades de 0 a 5, 5 a 10, 10 a 20 e 20 a 30 cm. Nessas amostras foram determinados os nutrientes: N, P, K, Ca e Mg, a matéria orgânica, a densidade do solo e os teores de argila. The replacement of forest by other land use can lead to significant losses in soil organic matter, changing its dynamic and the nutrients inputs and outputs of the system. The objective of this study was to assess nutrient stocks under different land use systems in Colorado do Oeste-RO. The agroforestry (teak, and cocoa), forestry (teak with five years), teak for eight years, farming areas (teak, cocoa and pasture) and pasture were the systems evaluated and the native forest was taken as reference. In each system three small trenches were dug, in which deformed and undeformed soil samples, at depths of 0 to 5, 5 to 10, 10 to 20 and 20 to 30 cm were taken. In these samples the nutrients N, P, K, Ca and Mg, organic matter, bulk density and clay content were determined. A completely randomized design with split plots and, three replications in each system was adopted. Differences were observed in soil nutrient stocks among the usage systems and with depth. The concentration of nutrients was influenced by the system. Ca was the nutrient most stored (2912.86 to 5188.48 kg ha -1 ) in all systems and K was the least(17.33 to 46.22 kg ha -1 ). The system of teak five years is the system which is closer to the forest, for the storage of nutrients.

Nutrient availability and organic matter content under different soil use and management

“…We notice that use and management systems were not efficient in increasing OM content in the 0.0-0.40 m depth at levels similar to or higher than NC. These negative correlations are different from those observed by Magalhães et al (2013), who evaluated nutrient stocks under different soil uses in Colorado do Oeste-RO; these authors concluded that the principal component analysis reduced the original variables to two main components, and the OM content was one of the variables that most contributed to the formation of MC1.…”

Organic Carbon and Total Nitrogen in the Densimetric Fractions of Organic Matter Under Different Soil Management

“…This argument is justified because, as reported by Rangel and Silva (2007), Iwata et al (2012) and Magalhães et al (2013), systems that favor the constant production of plant or animal biomass increase the content of carbon and various nutrients in the soil including nitrogen.…”

Spatialization of Fractions of Organic Matter in Soil in an Agroforestry System in the Atlantic Forest, Brazil

“…Current techniques can reverse or reduce the negative impacts of deforestation, reconciling food production with increasing biodiversity and protecting soil against degradation . The agroforestry system (AFS) is a form of land management, in which trees, agricultural crops and / or animals are intercropped, being deployed simultaneously or sequentially (MAGALHÃES et al, 2013). This system is a form of soil use that combines agricultural production and the conservation of natural resources (JOSE, 2009), providing environmental services such as soil conservation, carbon sequestration, biodiversity preservation, and an increase in water quality (NAIR, 2011).…”