Tillage and mineral fertilization are important strategies for maintaining crop production, but their effects on soil organic carbon (SOC) and labile fractions in semiarid regions are controversial. A 10-year field experiment was conducted to evaluate the effects of fertilization and tillage on SOC stock, labile fractions, soil quality and crop yields in a wheat–maize cropping system at the Loess Plateau. Results showed that balanced fertilization could provide comprehensive nutrition for crops and increase the crop residue input carbon, thereby increasing the SOC, readily oxidizable carbon, particulate organic carbon and dissolved organic carbon contents. In 0–50 cm layers, the SOC stock was increased by 3% under balanced fertilization compared to conventional fertilization. For tillage, no-tillage (zero tillage) and subsoiling rotation with less soil disturbance and higher stabilization rate of input carbon was the most effective tillage practice for increasing SOC stock. This tillage technique increased the labile carbon contents by 41%–63%, 5%–19% and 26%–67% compared to ploughing in 0–10 cm, 20–35 cm and 35–50 cm layers, respectively. Balanced fertilization combined with no-tillage and subsoiling rotation (BF + NS) increased carbon pool management index due to higher SOC and labile carbon contents, which contributed to the improvement of soil quality and the promotion of crop growth. Among all treatments, BF + NS treatment produced the highest SOC stock as well as wheat and maize yields. Therefore, BF + NS is the best strategy to increase SOC sequestration and to improve soil quality and productivity in semiarid regions.

中文翻译：

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半干旱区轮作施肥优化提高土壤有机碳库和作物产量

耕作和矿物施肥是维持作物生产的重要策略，但它们对半干旱地区土壤有机碳 (SOC) 和不稳定部分的影响存在争议。进行了为期 10 年的田间试验，以评估施肥和耕作对黄土高原小麦 - 玉米种植系统中 SOC 储量、不稳定部分、土壤质量和作物产量的影响。结果表明，平衡施肥可以为作物提供综合营养，增加作物秸秆输入碳，从而提高土壤有机碳、易氧化碳、颗粒有机碳和溶解有机碳的含量。在 0-50 cm 层中，与常规施肥相比，平衡施肥下 SOC 储量增加了 3%。对于耕作，免耕（零耕）和深松轮作具有较少的土壤扰动和较高的输入碳稳定率，是增加 SOC 储量的最有效耕作方式。与耕作 0-10 厘米、20-35 厘米和 35-50 厘米层相比，这种耕作技术使不稳定碳含量分别增加了 41%–63%、5%–19% 和 26%–67%。平衡施肥结合免耕深松轮作（BF+NS），由于较高的SOC和不稳定碳含量，提高了碳库管理指数，有助于改善土壤质量和促进作物生长。在所有处理中，BF + NS 处理产生最高的 SOC 储量以及小麦和玉米产量。因此，BF + NS 是增加半干旱地区 SOC 封存和改善土壤质量和生产力的最佳策略。