Resolving the Trade‐Offs by Conservation Deep Tillage

Conservation tillage may involve trade-offs between crop productivity and ecosystem services across different climatic and soil conditions (Zhang et al. 2026). While conservation tillage practices, with no-till as the core idea, can enhance soil organic carbon (SOC) sequestration, improve soil structure, and reduce erosion, these ecological benefits do not consistently translate into crop yield enhancement. Alternatively, traditional tillage such as ploughing can alleviate soil compaction and improve crop productivity, but at the cost of disrupting soil structure and reducing SOC stability (Zhang et al. 2026). A fundamental trade-off is therefore demonstrated between ecological conservation and agronomic performance, which is largely driven by subsoil constraints, particularly compaction, restricting root penetration and limiting access to water and nutrients in deeper soils (Kan et al. 2022; Keller et al. 2025; Zhang et al. 2026). This raises an important question of whether this trade-off can be reconciled by integrating the strengths of conservation tillage and traditional tillage through targeted subsoil management. Here, we provide evidence from a 15-year field experiment showing that conservation deep tillage, implemented through ditch-buried straw return, can effectively address this trade-off by integrating the benefits of conservation tillage and traditional tillage within a conservation framework (Kan et al. 2025). This practice disturbs only a small proportion of the soil, approximately 10%, through localized deep tillage at depths of 0.2–0.3 m, with the disturbed zones periodically rotated while maintaining the majority of the field under no-till conditions (Figure 1A) (Yang et al. 2019). This targeted intervention significantly reduces penetration resistance and bulk density in subsoil layers from 0.1 to 0.4 m compared with no-till (Figure 1B,C). These structural improvements are accompanied by enhanced aggregate stability (Figure 1D), as reflected by increased mean weight diameter, particularly in subsoil layers, suggesting improved soil structural integrity. As a consequence, root systems penetrate deeper into the soil profile, enhancing access to water and nutrients and improving belowground resource acquisition (Figure 1E). Concurrently, conservation deep tillage substantially increases soil organic carbon stocks by approximately 53% within the 0–0.4 m soil profile relative to no-till, due to enhanced carbon sequestration capacity in subsoil (Figure 1F). These improvements are associated with significant increases in grain yield, with wheat yields increasing by 16% and rice yields by 13% (Figure 1G,H). Collectively, these results demonstrate that targeted subsoil intervention can simultaneously enhance soil structure, SOC sequestration, and crop productivity, effectively reconciling the trade-offs between conservation tillage and traditional tillage. The effectiveness of conservation deep tillage arises from the coupling of soil structural improvement and biologically mediated carbon stabilization processes. By alleviating subsoil compaction and enhancing structural stability, conservation deep tillage facilitates deeper root penetration and improves access to water and nutrients, thereby supporting crop productivity. Meanwhile, straw burial and enhanced root growth increase carbon inputs to subsoil, providing substrates that promote aggregation and stimulate microbial activity (Fontaine et al. 2007; Six et al. 2000). Enhanced microbial turnover leads to the accumulation of microbial necromass, which contributes to the stabilization of mineral-associated organic carbon (Kan et al. 2025; Wen et al. 2025). Improved structural stability further enhances the physical protection of SOC, reinforcing its persistence in subsoil (Kan et al. 2022). Together, these interacting processes establish a functional linkage between soil structure, carbon inputs, and microbial transformation. Importantly, conservation deep tillage can be implemented using existing agricultural machinery with limited additional cost, making it suitable for large-scale farming systems (Kan et al. 2025; Wu et al. 2022). These findings suggest that integrating minimal disturbance with targeted subsoil improvement provides a practical and scalable pathway to overcome the inherent trade-offs between yield performance and ecosystemic benefits under conservation tillage, thereby enhancing ecosystem multifunctionality in agricultural systems. Zheng-Rong Kan: conceptualization, writing – review and editing, writing – original draft, funding acquisition. Johannes Lehmann: conceptualization, investigation, writing – review and editing. Feng-Min Li: writing – review and editing, investigation, conceptualization. Rattan Lal: conceptualization, visualization, writing – review and editing. Haishui Yang: conceptualization, supervision, writing – review and editing, project administration. This study was supported by the National Key R&D Program of China (2023YFD2302400) and the National Natural Science Foundation of China (32501545). The authors declare no conflicts of interest. This article is a Letter to the Editor regarding Zhang et al. https://doi.org/10.1111/gcb.70825. See also the Response to the Letter by Linchuan Fang, https://doi.org/10.1111/gcb.70940. Data sharing not applicable to this article as no datasets were generated or analyzed for the published articles.