No-till (NT) farming has been widely adopted to assist in reducing erosion, lowering fuel costs, conserving soil moisture and improving soil physical, chemical and biological characteristics. Improvements in soil characteristics are often driven by the greater soil organic matter accumulation (as measured by soil organic carbon (SOC)) in NT compared to conventional tillage (CT) farming systems. However, to fully understand the effect of NT it is important to understand temporal changes in SOC by monitoring over an extended period. We investigated the long-term effect of NT and stubble retention (SR) on changes in SOC and total soil nitrogen (STN) using results from an experiment that has been running for 50 years in a semi-arid subtropical region of north-eastern Australia. In this experiment, the effects of tillage (CT vs NT), residue management (stubble burning (SB) vs SR), and nitrogen (N) fertiliser (0 and 90 kg-N ha–1) were measured in a balanced factorial experiment on a Vertisol (Ustic Pellusert). The use of NT, SR and N fertiliser generally improved SOC (by up to 12.8%) and STN stocks (by up to 31.7%) in the 0–0.1 m layer relative to CT, SB and no N fertiliser, with the greatest stocks observed where all three treatments were used in combination. However, declines in SOC (up to 20%) and STN (up to 25%) occurred in all treatments over the course of the experiment, indicating that changes in management practices were unable to prevent a loss of soil organic matter over time in this farming system. However, the NT and SR treatments did lose less SOC than CT and SB treatments, and SR also reduced STN loss. The δ13C analysis of samples collected in 2008 and 2015 highlighted that crop residues have significantly contributed to SOC stocks at the site and that their contribution is increasing over time.

中文翻译：

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澳大利亚东北部Vertisol不同耕作、茬茬和施肥管理47年后土壤有机碳和氮的变化

免耕 (NT) 耕作已被广泛用于帮助减少侵蚀、降低燃料成本、保持土壤水分和改善土壤物理、化学和生物特性。与传统耕作 (CT) 耕作系统相比，北领地的土壤有机质积累量（以土壤有机碳 (SOC) 衡量）通常会推动土壤特性的改善。然而，要充分了解 NT 的影响，重要的是通过长时间监测来了解 SOC 的时间变化。我们使用在澳大利亚东北部半干旱亚热带地区进行了 50 年的实验结果，研究了 NT 和留茬 (SR) 对 SOC 和土壤总氮 (STN) 变化的长期影响. 在这个实验中，耕作的影响（CT vs NT），在 Vertisol (Ustic Pellusert) 上的平衡析因实验中测量了残留物管理（残茬燃烧 (SB) 与 SR）和氮 (N) 肥料（0 和 90 kg-N ha-1）。相对于 CT、SB 和不施氮肥，NT、SR 和 N 肥料的使用普遍提高了 0-0.1 m 层的 SOC（高达 12.8%）和 STN 储量（高达 31.7%），其中储量最大观察到所有三种处理组合使用的情况。然而，在整个试验过程中，所有处理的 SOC（高达 20%）和 STN（高达 25%）均出现下降，表明管理实践的变化无法防止土壤有机质随时间的推移而流失。农业系统。然而，NT 和 SR 处理确实比 CT 和 SB 处理损失更少的 SOC，并且 SR 也减少了 STN 损失。