The effects of long-term no tillage and stubble retention on soil nutrient, grain and forage productivity in a forage-crop rotation system in rainfed areas

We explored the changes in crop and forage productivity and their driving factors after 22 years of conventional tillage (T), conventional tillage combined with stubble retention (TS), no tillage (NT), and no tillage combined with stubble retention (NTS) in a forage-crop rotation system on the Loess Plateau. The results indicated that TS and NTS increased system production by 19% and 32%, respectively. Among them, NTS had the greatest effects on maize yield, wheat yield, soybean biomass, which increased by 19%, 14% and 52%, compared with T, respectively. Moreover, the NTS had the highest soil carbon and nitrogen accumulation, enzyme activity and soil conditions. The soil carbon and nitrogen storages of NTS increased by 41% and 53% in the 0-10 cm soil depth, respectively. Moreover, the activities of βG (β-glucosidase), CBH (cellobiohydrolase), βX (β-xylosidase), LAP (leucine-aminopeptidase), NAG (β-N-acetylglucosaminidase) of NTS increased by 45%, 98%, 39%, 50% and 53%, respectively.本研究针对黄土高原粮草轮作系统，探究了22年常规耕作（conventional tillage, T）、常规耕作结合秸秆还田（conventional tillage combined with stubble retention, TS）、免耕（no tillage, NT）以及免耕结合秸秆还田（no tillage combined with stubble retention, NTS）四种耕作模式下，作物与饲草生产力的变化及其驱动因子。研究结果显示，TS与NTS处理分别使系统生产力提升19%与32%。其中，NTS对玉米产量、小麦产量及大豆生物量的提升效果最为显著，相较T处理分别提升19%、14%与52%。此外，NTS处理的土壤碳氮累积量、酶活性及土壤理化状况均为最优。在0-10 cm土层中，NTS处理的土壤碳、氮储量分别提升41%与53%。此外，NTS处理下的β-葡萄糖苷酶（β-glucosidase, βG）、纤维二糖水解酶（cellobiohydrolase, CBH）、β-木糖苷酶（β-xylosidase, βX）、亮氨酸氨基肽酶（leucine-aminopeptidase, LAP）与β-N-乙酰氨基葡萄糖苷酶（β-N-acetylglucosaminidase, NAG）活性分别提升45%、98%、39%、50%与53%。