Matéria orgânica do solo em sistemas de produção agrícola e cerrado do oeste baiano

Abstract

Soil preparation causes carbon losses (C) through increased aeration, improved soil temperature and humidity, as well as the release of a fraction of the organic matter (OMS) from the labile previously protected by the aggregates to decomposition. In addition to contributing to this soil aggregation, it plays an important role in the ability of cations to be exchanged through their fractions, helping the nutrients to be used in the soil solution by plants. In this scenario, the search for a more sustainable management is constant in order to reduce the impacts of intensive agriculture. The West Region of Bahia has 2.4 million hectares of agricultural production of grains and fibers, with the potential to double this area with agricultural use in areas of native cerrado. Based on this information, the aim of this work was to verify the availability of the OMS of cultivated areas in comparison to the native forest areas of the Cerrado. Soil samples (0-10cm, 10-20cm deep) were collected in eight properties of ten Cerrado Baiano microregions, which were cultivated in two cropping systems (CPS - Conventional Planting System, and NTS – No-Tillage System), and from reservation areas ( NC - Native Cerrado). By means of the chemical extraction of Carbon by heating, the attributes TOC, OMS and Humic Fractions were accessed, and ECC was calculated. The results were submitted to a joint analysis by applying the student's t test to identify which region and which production system presented the highest levels of the analyzed attributes The systems of agricultural management presented significant differences among the microregions studied. It was verified that the West Region presents levels of OMS in the range classified as low (0.7 to 2.0% of OMS), except for the Micro-regions of COACERAL (2.47%) and Cascudeiro (2.26%). In relation to Humic Fractions, the West Region of Bahia presents 75% HF, 12% HAF, and 13% FAF., This behavior of for most of the microregions, except for Cascudeiro that presented 68% of HF, 21% of HAF, and 11% FAF. The COACERAL Microregion has the highest carbon sequestration rate, followed by the Cascudeiro, with 62.30 t ha-1 and 60.98 t ha-1.

KEYWORDS: OMS; No-tillage System, Carbon Sequestration, West of Bahia, MATOPIBA.