Effects of Mushroom Residue Organic Fertilizer Combined with Desulfurized Gypsum on Active Organic Carbon and Its Sensitivity in Saline-Alkali Soil of the Yellow River Delta

Abstract

[Objective] In order to investigate the effects of mushroom residue organic fertilizer and desulfurized gypsum on organic carbon components and carbon pool management index (CPMI) of saline-alkali soil. [Methods] The newly reclaimed wheat-maize rotation land in the Yellow River Delta was used as the research subject, and the randomized block experiment method was conducted to set up four treatments: no fertilization (CK), conventional farming fertilization (CN), mushroom residue organic fertilizer (MCOF), mushroom residue organic fertilizer and desulfurized gypsum (MCOG), which were treated by field fertilization for 3 years. [Results] The combined application of mushroom residue organic fertilizer and desulfurized gypsum significantly reduced the salinity of 0—20 cm soil layer, and increased the soil nitrogen, phosphorus and potassium nutrition content and cation exchange capacity (p<0.05). The contents of total organic carbon (TOC), easily oxidized organic carbon (EOC) and microbial biomass carbon (MBC) in 0—20 cm soil layer were higher than those in 20—40 cm soil layer, while the water-soluble organic carbon (WSOC) was lower than that in 20—40 cm soil layer. In the 0—20 cm soil layer, compared with the CN treatment, the MCOG treatment significantly increased soil TOC, EOC, WSOC, and MBC by 15.48%, 23.50%, 18.98%, and 51.40%, respectively. The effective rates of EOC and MBC increased by 13.94% and 30.49%, respectively. There was no significant effect on the effective rate of WSOC. The combined application of organic fertilizer and desulfurized gypsum significantly increased the soil CPMI, which increased by 15.38% and 20.00% compared with the CN and the CK treatments, respectively. The sensitivity index of MBC was higher than that of other organic carbon components, and the MBC value of MCOG treatment was the highest. Correlation analysis showed that soil TOC content depended on its active components, while the main factors affecting the content and effective efficiency of organic carbon active components, as well as the CPMI, are pH, CEC, and EC. [Conclusion] Therefore, the combined application of mushroom residue organic fertilizer and desulfurized gypsum can significantly decrease soil alkalinity, improve soil fertility and enhance carbon sequestration efficiency of saline-alkali soil. This research provides a theoretical basis and data support for expanding organic improvement methods in saline-alkali soil of the Yellow River Delta.

Keywords

• saline-alkali land
• mushroom residue organic fertilizer
• desulfurization gypsum
• activated organic carbon
• carbon pool management index