Abstract
Environmental benefits from bioenergy production derived from sugarcane crop residues (straw) can be lost by soil organic matter depletion resulting from excessive straw removal rates from fields. Soil organic carbon stock is the core for sustaining soil health, supporting nutrient cycling, and sequestering carbon dioxide. To find out that how much sugarcane straw can be removed from the field to produce bioenergy without changes in soil C concentrations, we investigated effects of straw removal rates (total, moderate, and no removal of sugarcane straw) on soil carbon and nitrogen fractions in an Oxisol and an Ultisol in southeastern Brazil for two years. Soil C and N fractions were affected by increased rates of straw removal at the second year. In the Oxisol, total straw removal decreased labile and microbial-C by ~30% and soil C stock by 20% compared to no straw removal. No removal decreased microbial-N and total N stock by ~15% and ~20%, respectively. In the Ultisol, no straw removal resulted in increases in C stock by >10% and labile and microbial-C by ~20% related to total straw removal. Total straw removal showed more microbial-N (~10%) and total-N stock (~25%) compared to no straw removal. The moderate straw removal intensity (i.e., 8 to 10 Mg ha−1 of straw) may control the straw-C release to soil by straw decomposition. This study suggests that excessive straw removal rates should be avoided, preventing SOM depletion and consequently, soil health degradation. Moderate straw removal seems to be a promising strategy, but long-term soil C monitoring is fundamental to design more sustainable straw management and bioenergy production systems.
Highlights
A global effort has been done to diversify energy sources and reduce the consumption of fossil fuels towards a planet safe from environmental threats [1]
The Nmic stock was influenced by total sugarcane straw removal from the field [S- -] (p < 0.10; Figure 3j) in the Ultisol site
The effects of straw removal showed significant depletion of soil microbial N stock upon complete removal of the sugarcane straw under Ultisol (p < 0.10; Figure 3j), suggesting that straw removal enhances the soil N mineralization due to the limited source of C for microbiota. In both experimental sites in 2016, soil Clab and Cmic stocks were the highest in the plots that sugarcane straw was maintained in the surface soil (p < 0.1, Figure 3c–f) and the concentration of those attributes in soil followed the same trend (p < 0.1 Supplementary material; Table S1), indicating an increase in labile and microbial fractions of soil C with decreasing in straw removal rates in both areas
Summary
A global effort has been done to diversify energy sources and reduce the consumption of fossil fuels towards a planet safe from environmental threats [1]. With gradual change on harvest systems in the last decade, the south-central region of Brazil has more than 90% of sugarcane fields being harvested mechanically in a green cane system management [8]. In this system, most of the sugarcane straw is maintained on the soil surface, equivalent to, on average, 14 Mg ha−1 yr−1 of straw (dry weight) in Brazilian sugarcane fields [9], which results in annual straw-carbon (C) inputs into the soil [10]. The amount of straw produced, and the soil C retention depend on climatic conditions, sugarcane type, and management practices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
