施入不同土层的秸秆腐殖化特征及对玉米产量的影响

耕作和秸秆还田是打破犁底层、改善黑土肥力的重要措施.本研究利用田间试验,分析了耕作和秸秆还田对秸秆腐殖化系数、总有机质含量(SOC)和玉米产量的影响.结果表明:深耕+秸秆施入20～35 cm(ST+S)能够打破犁底层,与浅耕(TT)、深耕(ST)和浅耕+秸秆还田(TT+S)相比,试验6年间土壤容重平均降低了5.7%、3.3%和5.7%,其中ST和ST+S试验第一年效果最好;试验6年后秸秆腐解率表现为0～20 cm土层(72.0%)>20～35 cm土层(59.2%);0～20和20～35 cm土层秸秆腐殖化系数在试验的第一年达到了最大值,分别为15.9%和12.7%;与初始土壤相比,TT、ST和ST+S处理0～20 cm土层SOC和轻组有机碳(LFOC)含量呈下降趋势,而TT+S处理分别增加了2.9%和12.4%,ST+S处理20～35 cm土层分别增加了9.2%和9.9%;对玉米产量的影响表现为ST+S>TT+S>ST>TT,耕作和秸秆还田的时间效应明显,其中ST处理玉米产量的影响可以持续3年,而ST+S处理可以持续6年.因此,通过耕作的方式将秸秆施入20～35 cm土层是一种有效的、可持续改善黑土质量的农业措施.

Effects of straw incorporated to different locations in soil profile on straw humification coefficient and maize yield.

Tillage and straw incorporation are important agricultural practices that can break plough layer and improve black soil fertility. The effects of tillage and straw incorporation on straw humification coefficient, soil organic carbon (SOC), and maize yield were investigated in a field experiment. Subsoil combined with straw incorporation in 20-35 cm soil layer (ST+S) could break plough layer and decrease the bulk density by 5.7%, 3.3% and 5.7% compared with traditional til-lage (TT), subsoil (ST) and traditional tillage combined with straw incorporation (TT+S) in six experimental years, respectively, and the best effects were observed in ST and ST+S treatments in the first expe-rimental year. The rate of straw decomposition was higher in 0-20 cm (72.0%) than in 20-35 cm (59.2%), and the straw humification coefficient in 0-20 cm and 20-35 cm soil la-yers reached the peak in first experimental year with 15.9% and 12.7%, respectively. Compared with initial soil sample, SOC and light fraction organic carbon (LFOC) of TT, ST and ST+S treatments in 0-20 cm soil layer was decreased in experimental years, but was increased by 2.9% and 12.4% within TT+S, respectively. SOC and light fraction organic carbon (LFOC) of ST+S in 20-35 cm soil layer was increased by 9.2% and 9.9%, respectively. The effect of field treatments on maize yield showed in a decreasing trend of ST+S>TT+S>ST>TT, effects of tillage and straw incorporation on maize yield could continue 3 and 6 years, respectively, indicating that tillage and straw incorporation had time effect. Therefore, straw incorporated into 20-35 cm soil layer based on tillage was an effective, sustainable agricultural practice of improving black soil quality.