State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China (the Institute of Agricultural Resources and Regional Planning), Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China (the Institute of Agricultural Resources and Regional Planning), Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
J Environ Manage. 2024 Dec;371:123130. doi: 10.1016/j.jenvman.2024.123130. Epub 2024 Oct 30.
Soil salinity poses a major threat to crop growth, microbial activity, and organic matter accumulation in agroecosystems in arid and semiarid regions. The limitations of carbon (C) accrual due to salinity can be partly mitigated by the application of organic fertilizers. Although microorganisms are crucial for soil organic carbon (SOC) stabilization, the relationships between living and dead microbial C pools and the community features of SOC accrual in saline soils are not known. A two-year field experiment was conducted to examine the effects of organic fertilizers on the microbial regulatory mechanisms of C sequestration in saline soil (chloride-sulfate salinity). Compared to manure addition alone, manure plus commercial humic acid increased SOC stock by 11% and decreased CO emissions by 10%, consequently facilitated soil C sequestration. We explain these results by greater bacterial necromass formation due to the dominance of r-strategists with faster turnover rate (growth and death), as well as larger necromass stability as supported by the increased aggregate stability under the addition of humic acids with manure. Humic acids increased the abundance of bacterial phylum Proteobacteria (copiotrophs) and decreased Acidobacteria (oligotrophs) compared with straw, indicating that r-strategists outcompeted K-strategists, leading to bacterial necromass accumulation. With larger C/N ratio (88), straw increased leucine aminopeptidase to mine N-rich substrates (i.e., from necromass and soil organic matter) and consequently reduced SOC stock by 8%. The decreased salinity and increased organic C availability under straw with manure addition also led to a 13% higher CO flux compared with manure application alone. Thus, humic acids added with manure benefited to SOC accumulation by raising bacterial necromass C and reducing CO emissions.
土壤盐度对干旱和半干旱地区农业生态系统中作物生长、微生物活性和有机物质积累构成重大威胁。盐分导致的碳（C）积累受限可以部分通过施用有机肥得到缓解。虽然微生物对土壤有机碳（SOC）稳定至关重要，但在盐渍土壤中，活微生物和死微生物 C 库与 SOC 积累的群落特征之间的关系尚不清楚。一项为期两年的田间试验研究了有机肥对盐渍土壤（氯化物-硫酸盐盐度）中 C 固存的微生物调节机制的影响。与单独添加粪肥相比，粪肥加商品腐殖酸增加了 11%的 SOC 储量，并减少了 10%的 CO 排放，从而促进了土壤 C 固存。我们通过由于更快周转率（生长和死亡）的 r 策略者的主导地位导致的更大细菌尸体形成，以及腐殖酸与粪肥一起添加时由于更大的团聚体稳定性而支持的更大的尸体稳定性来解释这些结果。腐殖酸增加了细菌门变形菌（富养生物）的丰度，并降低了酸杆菌（寡养生物）的丰度，与秸秆相比，这表明 r 策略者竞争过 K 策略者，导致细菌尸体积累。秸秆的 C/N 比（88）较大，增加了亮氨酸氨肽酶以挖掘富含 N 的底物（即来自尸体和土壤有机质），从而使 SOC 储量减少了 8%。与单独施用粪肥相比，由于秸秆添加粪肥降低了盐分并提高了有机 C 的有效性，CO 通量也增加了 13%。因此，腐殖酸加粪肥有利于通过提高细菌尸体 C 和减少 CO 排放来促进 SOC 积累。
