Glomalin contribution to soil organic carbon under different pasture managements in a saline soil environment
Natalia Banegas, Daniel Andrés Dos Santos, Fernanda Guerrero Molina, Ada Albanesi, Raúl O. Pedraza
Abstract
The glomalin produced by arbuscular mycorrhizal fungi has beneficial effects on soils. We studied the vertical profile of glomalin-related soil protein (GRSP) in pasturelands grown under saline soils and exposed to different management practices. Treatments included haying and grazing of Chloris gayana subject to either N-fertilization or not. We measured mycorrhizal colonization, spores, root biomass, total GRSP, GRSP-carbon (GRSP-C), organic carbon (OC) and total nitrogen (TN). In the meanwhile, we also developed a mathematical procedure to fit continuous power functions to binned soil data. Power decay functions adjusted excellently well the measured data across the 1-meter soil profile. Meaningful increases of root biomass, OC, TN, GRSP and GRSP-C values were associated with grazing and fertilization. Particularly, GRSP-C averaged 1,134 kg C ha−1 at the beginning experiments and increased significantly up to 1,261 kg C ha−1 in grazed and fertilized pastures at the end of the study period. Carbon accounted for between 17% and 50% of GRSP, representing in turn 0.52–1.62% of SOC stock. So, a tropical perennial grass can contribute to the carbon stock in saline soils by promoting production of GRSP. This contribution increases when inputs and cycling of nutrients are enhanced (grazing and N-fertilization).