Humate Combined with Film-Mulched Ridge-Furrow Tillage Improved Carbon Sequestration in Arid Fluvo-Aquic Soil

Abstract

Commercial humic fertilizers (humates) can be used to improve carbon sequestration. In this study, a 3-year field trial (2016–2018) employed four treatments to investigate the mechanism by which humate increases carbon sequestration in fluvo-aquic soils: (1) blank: bare soil with no agricultural treatment; (2) control: standard film mulch (FM) ridge-furrow tillage (which acts as CK); (3) humate: FM tillage plus humate; and (4) straw: FM tillage plus straw. The three treatments strongly affected the soil carbon sequestration, with the humate and straw treatments more significant than the blank treatment. Moreover, the ≥2.0-mm macroaggregate fraction, >1-mm soil aggregate-associated carbon, weight mean diameter (MWD) and geometric mean diameter (GMD), and microbial biomass nitrogen (MBN) values for the straw and humate treatments were all significantly increased (p < 0.05), increasing the carbon sequestration by 1.9 and 0.9 Mg C ha−1y−1 compared to the control, respectively. Carbon sequestration was significantly associated with >1.0-mm aggregate-associated C, MWD, GMD, MBN, and organic C input. Humate and straw synergistically regulate the soil and microbial processes and greatly increase the straw C return to soil while efficiently increasing the macroaggregate fraction and stability, macroaggregate-associated carbon, and physical protection of aggregates, thereby increasing the carbon sequestration. Therefore, humate may be a novel economical alternative to straw to efficiently increase the carbon sequestration in dry fluvo-aquic soils.