酸性稻田添加生物炭对水稻生长发育及产量的影响——基于5年大田试验

Effects of biochar on growth and yield of rice in an acidic paddy field: findings from a five-year field trial

开展生物炭对农田生态系统长期效应的大田试验对全面评价生物炭调控农田生产力的效果具有重要意义。以南方酸性稻田为对象,采用单因素随机区组设计开展了5年大田试验,探讨不同水平生物炭(0、20、40、60、80 t/hm^2和100 t/hm^2)一次性添加对水稻生长和产量的多年效应。主要结果为:(1)水稻齐穗期的LAI、倒4叶叶绿素含量及地上部干物质积累量和产量均随生物炭添加量增加而增加;(2)生物炭对齐穗期剑叶叶绿素含量以及粒叶比的影响不显著;(3)生物炭显著促进稻田增产的添加量分别为:≥60 t/hm^2(增幅17.0%—23.7%,第1年)、≥40 t/hm^2(增幅15.5%—32.4%,第2年)、20—100 t/hm^2(增幅9.6%—21.8%,第3年)、均无显著差异(第4年)、100 t/hm^2(增幅15.7%、第5年);(4)生物炭对稻田累计产量的增幅分别为:5.9%—23.7%(第1年)、5.5%—27.8%(第2年)、6.8%—25.9%(第3年)、5.4%—22.0%(第4年)、4.6%—20.6%(第5年);(5)产量与齐穗期的LAI、倒4叶叶绿素含量、干物质积累量及每穗粒数显著正相关。综上表明:酸性稻田生物炭一次性添加有利于改善水稻群体质量,促进稻田增产,高炭量添加(80 t/hm^2和100 t/hm^2)相比于中低炭量添加持续增产效应更好,至少可稳定维持3年。研究结果可为指导生产实践中利用生物炭以实现稻田增产提供科技支撑。

Biochar has been widely suggested as an effective amendment to improve crop growth and productivity. However, its long-term effects on rice growth and productivity, especially in acidic paddy are less understood. We conducted a five-year(2015—2019) field experiment with the single factor randomized block design in an acidic paddy of Changsha, Hunan Province, south China. We aim to investigate(1) how do rice growth and productivity respond to different amount of biochar amendment(i.e., 0 t/hm^2(CK), 20 t/hm^2(B20), 40 t/hm^2(B40), 60 t/hm^2(B60), 80 t/hm^2(B80), and 100 t/hm^2(B100)) and(2) how long can the effects of biochar amendment sustain? The results showed that:(1) leaf area index(LAI), the chlorophyll content of the reciprocal fourth leaf, and dry matter accumulation at the heading stage increased with the increasing amount of biochar amendment, so did the rice yield.(2) Biochar amendment showed no significant effects on the chlorophyll content of the flag leaf at the heading stage and the grain-leaf area ratio.(3) The amount of biochar amendment significantly impacted its role in increasing rice yield. Rice yield significantly increased 17.0%—23.7% in the first year with ≥ 60 t/hm^2 biochar amendment compared with CK). The corresponding numbers for the other four years were 15.5%—32.4% rice yield increase with ≥40 t/hm^2 biochar amendment in the second year, 9.6%—21.8% rice yield increase with 20—100 t/hm^2 biochar amendment in the third year, no significant increase for all treatments in the fourth year, and 15.7% rice yield increase with 100 t/hm^2 biochar amendment in the fifth year.(4) Biochar amendment increased the accumulated rice yield for the consecutive five years by 9%—23.7%, 5.5%—27.8%, 6.8%—25.9%, 5.4%—22.0%, and 4.6%—20.6%, respectively.(5) Rice yield significantly correlated with LAI, the chlorophyll content of the reciprocal fourth leaf, and dry matter accumulation at the heading stage, and also significantly correlated with grain number per panicle. We found that biochar amendment could significantly improve rice growth and productivity in acidic paddy and the effects were stronger with higher amount of biochar amendment(i.e., 80 t/hm^2 and 100 t/hm^2). We also found these effects could sustain at least three years. The findings of this study can extend our understanding of the long-term effects of biochar amendment on rice growth and productivity and can also help farmers to increase rice yield through proper biochar amendment in acidic paddy.