豆科覆盖作物通过刺激微生物转化，比非豆科覆盖作物固存更多的土壤有机碳

豆科覆盖作物通过刺激微生物转化，比非豆科覆盖作物固存更多的土壤有机碳

本文原文为英文，由AI翻译而来。

覆盖作物是用于增加土壤有机碳固存的气候智能型农业措施之一。然而，不同覆盖作物（尤其是果园农业生态系统）的 SOC 固碳潜力及其内在机制尚未完全阐明。在此，我们利用 SOC 分馏方法、高通量测序和生物标记分析对中国的三个果园进行了调查。我们的目标是确定覆盖作物对 SOC 物理组分和化学成分以及微生物特性的影响，并阐明为什么豆科和非豆科覆盖作物对 SOC 的固碳效果不同。

研究结果表明，与未种植覆盖作物的对照地块相比，豆科和非豆科覆盖作物增加的 SOC 不同（+38% vs +16%）。豆科植物覆盖作物增加了矿质相关有机碳和颗粒有机碳，而非豆科植物覆盖作物只增加了矿质相关有机碳。这些差异归因于它们对微生物 SOC 转化途径的不同影响。

豆科覆盖作物通过增加土壤基质和氮的可用性对微生物转化途径产生了积极影响，如溶解有机碳（+84%）、O-烷基碳（+18%）和铵态氮（+42%）。碳酶和氮酶活性、微生物群落多样性指数、优势真菌类群（脊索真菌）丰度、微生物生物量碳（+105%）和微生物坏死物质碳（+47%）的增加也证实了这些结果。

非豆科作物覆盖可能会导致微生物缺氮，从而降低微生物途径的效率，β-葡萄糖苷酶与β-N-乙酰葡萄糖苷酶的比率较低（-7%）以及细菌香农指数或微生物坏死物质碳没有显著变化就证明了这一点。

此外，冗余分析表明，酶活性、微生物群落和微生物坏死碳共同主导了 SOC 物理组分的变化。特定地点的土壤特性（如土壤质地和氮的可用性）是影响覆盖作物下 SOC 固碳的重要因素。

我们的研究为优化覆盖作物管理以增加果园农业生态系统中的 SOC 固碳提供了重要启示。

Legume cover crops sequester more soil organic carbon than non-legume cover crops by stimulating microbial transformations

Cover crops are one of the climate-smart agricultural practices used to increase soil organic carbon (SOC) sequestration. However, the SOC sequestration potential and underlying mechanisms under different cover crops, especially in orchard agroecosystems, have not been fully elucidated. Here, we investigated three orchards in China using SOC fractionation methods, high-throughput sequencing, and biomarker analysis. Our objectives were to determine the effect of cover crops on the physical fractions and chemical compositions of SOC, as well as on microbial properties, and to clarify why legume and non-legume cover crops sequester SOC differently.

The results showed different increases in SOC between legume and non-legume cover crops (+38% vs. +16%) compared with those in the control plots without cover crops. Legume cover crops increased mineral-associated and particulate organic carbon, whereas non-legume cover crops increased mineral-associated organic carbon only. These differences were attributed to their distinct effects on microbial SOC transformation pathways.

Legume cover crops positively impacted microbial pathways by increasing the availability of soil substrates and nitrogen, such as dissolved organic carbon (+84%), O-alkyl carbon (+18%), and ammonium nitrogen (+42%). These results were supported by the increases in carbon and nitrogen enzyme activities, microbial community diversity indices, the abundance of dominant fungal taxa (Sordariomycetes), microbial biomass carbon (+105%), and microbial necromass carbon (+47%).

Non-legume cover crops might have induced microbial nitrogen starvation, decreasing the efficiency of microbial pathways, as evidenced by the low β-glucosidase to β-N-acetylglucosaminidase ratios (−7%) and the lack of significant changes in the bacterial Shannon index or microbial necromass carbon.

In addition, redundancy analysis revealed that enzyme activity, the microbial community, and microbial necromass carbon collectively dominated the changes in the SOC physical fraction. Site-specific soil properties such as soil texture and nitrogen availability were important factors influencing SOC sequestration under cover crops.

Our study provides essential insights for optimizing cover crop management to increase SOC sequestration in orchard agroecosystems.