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).

摘要

丛枝菌根真菌产生的球菌素对土壤有益。我们研究了盐渍土下生长的牧场中glomalin相关土壤蛋白（GRSP）的垂直分布，并暴露于不同的管理实践。治疗包括干草和放牧Chloris gayana无论是否施氮肥。我们测量了菌根定殖、孢子、根生物量、总 GRSP、GRSP-碳 (GRSP-C)、有机碳 (OC) 和总氮 (TN)。同时，我们还开发了一种数学程序，将连续幂函数拟合到分箱土壤数据中。功率衰减函数很好地调整了 1 米土壤剖面上的测量数据。根系生物量、OC、TN、GRSP 和 GRSP-C 值的显着增加与放牧和施肥有关。特别是，GRSP-C 在开始实验时平均为 1,134 kg C ha ^-1，并显着增加至 1,261 kg C ha ^-1在研究期结束时在放牧和施肥的牧场中。碳占 GRSP 的 17% 到 50%，反过来又占 SOC 存量的 0.52% 到 1.62%。因此，热带多年生草可以通过促进 GRSP 的生产来增加盐碱地的碳储量。当养分的投入和循环增加（放牧和氮肥）时，这种贡献就会增加。