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Low wheat grain yield under conservation tillage has been reported, and growth duration could determine the yield. Thus, an 11-year field experiment was conducted to assess the relationship between growth duration and grain yield under different tillage and residue managements. Four treatments were investigated: no-till with residue removal (NT0), conventional tillage with residue removal (CT0), no-till with residue retention (NTR, conservation tillage), and conventional tillage with residue incorporation (CTR). Beginning at 20 days after anthesis (DAA), NTR significantly increased physiological activities, indicating that NTR had a longer growth duration. NTR significantly prolonged growth duration by 2–3 days compared with the other treatments attributed to delayed emergence of seedlings caused by higher soil compaction and moisture under NTR. The CT0 had the highest grain yield on the standard harvest date used in the local area (36 DAA). Whereas the plants in NTR reached physiological maturity (39 DAA), the grain yield in NTR was significantly increased by 7.8–8.8% compared with yield at 36 DAA, and no significant difference was observed between NTR and CT0 due to the increased thousand kernel weight of NTR. Thus, it is practicable for harvesting at physiological maturity in NTR to obtain higher grain yield. [ABSTRACT FROM AUTHOR]

Mechanisms of soil organic carbon (SOC) stabilization have been widely studied due to their relevance in the global carbon cycle. No‐till (NT) has been frequently adopted to sequester SOC; however, limited information is available regarding whether sequestered SOC will be stabilized for long term. Thus, we reviewed the mechanisms affecting SOC stability in NT systems, including the priming effects (PE), molecular structure of SOC, aggregate protection, association with soil minerals, microbial properties, and environmental effects. Although a more steady‐state molecular structure of SOC is observed in NT compared with conventional tillage (CT), SOC stability may depend more on physical and chemical protection. On average, NT improves macro‐aggregation by 32.7%, and lowers SOC mineralization in macro‐aggregates compared with CT. Chemical protection is also important due to the direct adsorption of organic molecules and the enhancement of aggregation by soil minerals. Higher microbial activity in NT could also produce binding agents to promote aggregation and the formation of metal‐oxidant organic complexes. Thus, microbial residues could be stabilized in soils over the long term through their attachment to mineral surfaces and entrapment of aggregates under NT. On average, NT reduces SOC mineralization by 18.8% and PE intensities after fresh carbon inputs by 21.0% compared with CT (p <.05). Although higher temperature sensitivity (Q10) is observed in NT due to greater Q10 in macro‐aggregates, an increase of soil moisture regime in NT could potentially constrain the improvement of Q10. This review improves process‐based understanding of the physical and chemical mechanism of protection that can act, independently or interactively, to enhance SOC preservation. It is concluded that SOC sequestered in NT systems is likely to be stabilized over the long term. [ABSTRACT FROM AUTHOR]

Soil total nitrogen (STN) and the carbon/nitrogen ratio (C/N) influence both crop production and microbial activity, but their distributions under different tillage practices are not clearly understood. This study investigated the effects of tillage practices on the vertical and temporal distributions of STN and the C/N ratio as well as on the distributions of STN fractions in a double rice cropping system from 2012 to 2017. Four tillage practices were established in 2005 in Southern China, i.e. no-till with rice straw mulch (NTS), rotary tillage with rice straw retention (RTS), plough tillage with rice straw retention (CTS), and with rice straw removal (CT). Even at 20–30 cm soil depth, long-term rice straw retention significantly increased STN and its fractions compared to those for CT. Noticeably, at 0–5 cm soil depth, the C/N ratio under NTS was 1.6–6.5% lower than those of other treatments, with a larger amount of rice straw input. In addition, long-term rice straw retention (NTS, RTS, and CTS) increased rice yield by 6.2–14.2% compared to that for CT. Therefore, long-term rice straw retention is recommended in this region due to its ability to increase N accumulation (even at deeper soil depths), which might improve the rice production. [ABSTRACT FROM AUTHOR]