Abstract
The substitution of native vegetation by agricultural ecosystems can change the quantity and quality of soil organic matter (SOM), and the intensity of these changes depends on the soil type, climate, and land use. The objective of this study was to evaluate the quality of organic matter in chronosequences of Jatropha cultivation in contrasting soil and climatic conditions. Soil samples were evaluated at depths of 0.00-0.10, 0.20-0.30, and 0.80-1.00 m in chronosequences located in Planaltina, Distrito Federal (Cerrado-Pasture-Jatropha), Dourados, Mato Grosso do Sul (Atlantic Forest-Corn-Jatropha), and Araripina, Pernambuco (Caatinga-Jatropha). To assess SOM quality, we determined C contents in the SOM fractions, C stocks, the carbon management index (CMI), the SOM humification index (HLIF), and the C and N concentrations in the microbial biomass. The conversion of native vegetation to agropastoral systems changed the composition of SOM in the biomes evaluated, especially in the surface layers. The CMI and the C and N contents in the microbial biomass were the most responsive to land use changes in all the biomes studied. The pasture improved SOM quality by increasing the CMI (116) and the C content by 8, 21, and 6 % in the organic, mineral, and organomineral fractions, respectively, while maintaining the SOM humification index and the C and N contents in the microbial biomass in the 0-0.10 m layer. The lowest values of C in the SOM fractions, the CMI (52), and C microbial biomass (136 mg kg-1) were observed for annual crops. Jatropha cultivation increased C contents in the SOM fractions, C stocks, the CMI, and C and N in the microbial biomass with an increase in cultivation time, which demonstrates the potential of this long-term system for improving SOM quality.
Highlights
The most recent report prepared by the Intergovernmental Panel on Climate Change (IPCC) emphasizes that the greenhouse gas (GHG) emissions from anthropic actions, including farming, are the main causes of climate changes (Stavi and Lal, 2013; IPCC, 2014)
Jatropha cultivation increased C contents in the soil organic matter (SOM) fractions, C stocks, the carbon management index (CMI), and C and N in the microbial biomass with an increase in cultivation time, which demonstrates the potential of this long-term system for improving SOM quality
The use of biodiesel produced from oilseed plants such as Jatropha spp. can bring important benefits by substituting fossil fuels, which attenuates the exacerbated accumulation of greenhouse gases in the atmosphere
Summary
The most recent report prepared by the Intergovernmental Panel on Climate Change (IPCC) emphasizes that the greenhouse gas (GHG) emissions from anthropic actions, including farming, are the main causes of climate changes (Stavi and Lal, 2013; IPCC, 2014). Among the oilseed plants available for biodiesel production, various species of the Jatropha genus are promising due to their high oil production per unit of growing area and adaptability to marginal and degraded areas that are unsuitable for food, not competing with food crops (Wani et al, 2012). The use of biodiesel produced from oilseed plants such as Jatropha spp. can bring important benefits by substituting fossil fuels, which attenuates the exacerbated accumulation of greenhouse gases in the atmosphere. It is estimated that reduction in GHG emissions by replacing fossil fuels with biodiesel (i.e., offsetting) ranges from 30 to 60 % (Souza et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
