Short‐term Responses of Soil Organic Carbon and Chemical Composition of Particle‐associated Organic Carbon to Anaerobic Soil Disinfestation in Degraded Greenhouse Soils

Anaerobic soil disinfestation (ASD) is a short-term practice to conquer soil degradation, yet its effects on soil organic carbon (SOC) and its composition remain unclear. A field experiment was conducted in degraded greenhouse soils (C-3) that were previously used for production of vegetable (VP) and flower (FP), with three treatments (i.e., control, ST [maize straw addition [C-4]] and ASD [both ST and water flooding]) for 21 days. Results indicated that the control soil lost 1.3 Mg C ha(-1) in VP and 0.94 Mg C ha(-1) in FP, while ST increased SOC storage by over 1.0 Mg C ha(-1) in both VP and FP. The ASD increased SOC storage by over 2.0 Mg C ha(-1) by forming new SOC and decreasing old SOC loss. Additionally, ASD increased OC concentration in particulate size fractions, particularly in particulate organic matter (POM) with lower basal respiration, and higher hydrophobicity as indicated by an increased ratio of C-H/C=O from POM observed by FTIR. The SEM-EDS found an enhanced C signal in particle size fractions, especially in POM. Overlap of C, O, Si, Ca, and Fe in mineral-associated organic matter upon ASD indicated the possible crosslinking between intra-OC and minerals containing O, Si, Ca, and Fe. The ASD also controlled soil salinization and the pathogen Fusarium oxysporum, resulting in increased tomato yields in both VP and FP. Overall, apart from increasing tomato yields, ASD can enhance SOC storage by increasing OC in particle size fractions within a short term.