Soil microbes in the topsoil have long been the centre of cropping systems, yet the influence of subsoil microbes on soil functions remains elusive. Sustainable crop management will require an in-depth understanding of interactions of cropping patterns, soil microbials and multifunctionality. This study aimed to explore the relationships between soil microbials and multifunctionality in both topsoil and subsoil of different cropping systems. We did paired samplings from four cash crops and adjacent wheat/ maize rotation system fields at 0–15 cm and 15–30 cm depths on calcareous soils: cotton (C)-wheat (WC), grape (G)-wheat (WG), vegetable (V)-wheat (WV) and watermelon (W)-wheat (WW). The results showed that soil multifunctionality in topsoil was higher than in subsoil across all soil samples. In topsoil, soil multifunctionality in W was significantly higher than other cash crops, and the highest and lowest values were in the WG and WC, respectively. In the subsoil, soil multifunctionality in the C was significantly lower than other cash crops. Across the wheat fields, soil multifunctionality were significantly higher in WG and WW than in WC and WV. The structural equation model showed that soil organic carbon, bacterial community composition and fungal diversity were positively correlated with soil multifunctionality in both soil depths. Proteobacteria and Bacteroidetes in topsoil were the important drivers, while Firmicutes and Gemmatimonadetes were in the subsoil. Our results suggest that microbes in both topsoil and subsoil should be integrated into agricultural management practices. The alteration of fungal diversity and bacterial community composition may significantly affect soil multifunctionality in intensive agroecosystems.

中文翻译：

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细菌分类群和真菌多样性是决定不同种植系统土壤多功能性的关键因素

表土中的土壤微生物长期以来一直是种植系统的中心，但底土微生物对土壤功能的影响仍然难以捉摸。可持续作物管理将需要深入了解种植模式、土壤微生物和多功能性之间的相互作用。本研究旨在探讨不同种植系统表土和底土中土壤微生物与多功能性之间的关系。我们在 0-15 厘米和 15-30 厘米深度的钙质土壤上对四种经济作物和相邻的小麦/玉米轮作系统田地进行了配对采样：棉花 (C)-小麦 (WC)、葡萄 (G)-小麦 (WG) 、蔬菜 (V)-小麦 (WV) 和西瓜 (W)-小麦 (WW)。结果表明，在所有土壤样品中，表土的土壤多功能性高于底土。在表土中，W 的土壤多功能性显着高于其他经济作物，最高和最低值分别在 WG 和 WC 中。在底土中，C中土壤多功能性显着低于其他经济作物。在整个麦田中，WG 和 WW 的土壤多功能性显着高于 WC 和 WV。结构方程模型表明，土壤有机碳、细菌群落组成和真菌多样性与两种土壤深度的土壤多功能性呈正相关。表土中的变形杆菌和拟杆菌是重要的驱动因素，而底土中的厚壁菌门和 Gemmatimonadetes 是重要的驱动因素。我们的研究结果表明，表土和底土中的微生物应纳入农业管理实践。