Qualitative changes of organic matter affected by soil use and management systems as revealed by spectroscopic techniques

Abstract

Inappropriate land use through conversion of native vegetation to agriculture, with intensive tillage, has been decreasing the soil organic matter (SOM) and increasing greenhouse gases (GHG) emissions, especially CO2. However, conservation agriculture techniques, like no till, has been helping to reverse this process and several studies have demonstrated its beneficial effect in increasing SOM and soil quality. Nevertheless, qualitative changes in SOM from different soil use and management systems are still unknown, especially in tropical and subtropical soils. Thus, this project aims to advance in the knowledge about the chemical and structural composition of SOM and its stabilization mechanisms in management systems. This enables the development of strategies that promote the long-term sequestration and maintenance of SOM in the soil. As a result, it will efficiently contribute for the GHG mitigation and for the improvement of environmental quality in agricultural lands. To achieve the objectives of this project, it will be used soil samples from three long-term experiments in the soil use and management, located in subtropical and tropical regions of Brazil. Several spectroscopic techniques will be used in intact soil, functional fractions and humic substances, in order to determine their humification degree and recalcitrance. (AU)