Effect of sugarcane residue management (pre-harvest burning versus green cane retention) on soil organic carbon fractions and aggregate stability in Umbric Rhodic Ferralsols

Abstract

ABSTRACT Pre-harvest burning of sugarcane is a major management system globally and could have a significant effect on soil organic carbon (SOC) fractions, aggregates stability and nutrient cycling, while green cane harvest system can be more beneficial to soil quality and environmental sustainability. The current study examined the effects of sugarcane harvest systems on SOC fractions and aggregate stability of sandy loam Umbric Rhodic Ferralsols, with relatively high SOC. Soil aggregate stability was determined using the wet-sieving method. SOC fractions were determined using the physical and chemical separation method, thereafter the SOC content in different fractions was determined by the wet oxidation method. Pre-harvest burning reduced soil aggregate stability by >100 and 64.3% when compared to green cane in the top 0–5 and 5–10 cm depths, respectively. The carbon in the macro-aggregates fraction constituted more than 60% of total SOC, making it the primary C storage fraction for both green cane and pre-harvest burning. Pre-harvest burning had 20.4 and 45.2% lower SOC content in macro- and micro-aggregate fractions, respectively, when compared to green cane. Also, coarse particulate organic matter carbon and fine particulate organic matter carbon were lower in pre-harvest burning management after the dispersion of macro-aggregates when compared to green cane. Pre-harvest burning increased mineral-associated C in µSilt + µClay from bulk soil fractionation by 23.7% when compared to green cane. All the C fractions decreased with an increase in soil depth in both green cane and pre-harvest burning, except for the mineral-associated C. These findings demonstrate that green cane production increases aggregate stability and SOC storage in different soil fractions, with a potential reduction in greenhouse gas emission and sustainable sugarcane production when compared with the pre-harvest burning on sandy loam Umbric Rhodic Ferralsols.