短期秸秆颗粒还田对小麦-玉米系统作物产量与土壤呼吸的影响

Effects of short-term granulated straw incorporation on grain yield and soil respiration in awinter wheat-summer maize cropping system

秸秆直接还田易造成土秸混合度差、秸秆腐解慢和幼苗群体质量差等问题,不利于作物稳产和增产.秸秆颗粒具有还田性能好、还田质量高的优点,但还田后对作物生长和土壤碳排放特征的影响仍不清楚.通过田间微区试验,以秸秆不还田和常规粉碎还田为对照,分析了秸秆颗粒还田对冬小麦和夏玉米籽粒产量、还田一年内土壤呼吸速率和土壤碳排放效率的影响,为改进秸秆还田方式提供理论依据.结果表明:秸秆颗粒还田显著提高了冬小麦和夏玉米籽粒产量,其周年作物产量较秸秆不还田和常规粉碎还田分别显著提高14.0%和5.8%.秸秆颗粒还田促进土壤碳排放,其小麦生长季和玉米生长季土壤呼吸速率和碳累积排放量显著高于秸秆不还田.与常规粉碎还田相比,秸秆颗粒还田显著提高了冬小麦生长季土壤呼吸速率和碳累积排放量15.2%和8.9%,但夏玉米生长季两者无显著差异.此外,秸秆颗粒还田降低了土壤呼吸温度敏感指数(Q_(10)),提高了土壤碳排放效率.与秸秆不还田和常规粉碎还田相比,秸秆颗粒还田土壤呼吸敏感指数显著降低22.6%和10.1%,周年土壤碳排放效率提高2.3%和1.9%.可见,秸秆颗粒还田短期内显著促进土壤碳排放,但由于较高的作物产量,其碳排放效率能维持在较高水平.在黄淮海粮食主产区,秸秆颗粒还田可以作为一种新型的秸秆还田方式,但其土壤碳排放的长期效应仍需进一步研究.

Direct straw return to soils often leads to poor combination between soil and straw, decreases straw decomposition and suppresses crop growth. Those problems hamper crop yield and its stability. Granulated straw with high bulk density and small volume improves the straw quality and the soil-straw combination. It remains unknown how does the practice influence soil carbon emission and grain yield. A micro-field experiment was carried out to investigate the responses of wheat and maize yields, soil respiration and soil carbon use efficiency. There are three treatments： No straw incorporation （CK）, conventionally chopped straw incorporation （CCSI）, and granulated straw incorporation （GSI）. The results showed that the GSI treatment increased grain yield. Compared with the CK and CCSI treatments, the total yield of wheat and maize was significantly increased by 14.0% and 5.8%, respectively. Meanwhile, the GSI treatment promoted soil carbon emission. The average rate of soil respiration and the cumulative carbon emission during growing season were significantly higher than that in the CK treatment. Compared with the CCSI treatment, the rate and the cumulative amount of soil carbon emission during the wheat growing season were significantly elevated by 15.2% and 8.9%, but there was no significant difference during the maize growing season. The GSI treatment decreased the sensitivity of soil respiration to temperature and increased soil carbon use efficiency. Compared with the CK and CCSI treatments, the sensitivity of the GSI treatment was significantly decreased by 22.6% and 10. 1%, and the efficiency was increased by 2.3% and 1.9%. Although granulated straw incorporation promoted soil carbon emissions, it had higher soil carbon use efficiency than conventionally chopped straw incorporation due to the higher yield. The application of granulated straw incorporation could serve as a new option of straw return to soil in Huang-Huai-Hai region. Further research was needed to understand the longterm effects of granulated straw incorporation on soil carbon emission.