Meitan xuebao (Jul 2023)
Temporal response of soil carbon pool and agricultural productivity to different tillage methods in reclaimed land of mining area
Abstract
It is of great theoretical and practical value to reclaim the land destroyed by mining and explore the scientific farmland management modes for alleviating the contradiction between people and land and rapidly improving the productivity of reclaimed land. A long-term positioning experiment in the reclaimed soil of the mining area was conducted to explore a suitable tillage mode that is conducive to the rapid improvement of the reclaimed soil quality by comparing soil organic carbon (SOC), active organic carbon (AOC), carbon pool management index (ICPM) and yield performance under different tillage measures. Four tillage treatments including no-tillage (NT), shallow tillage (ST), deep tillage (DT) and DT-ST alternate rotation (DST) were set up before wheat sowing. The results showed that: ① Different tillage methods have different effects on SOC accumulation through influencing soil carbon sequestration rate (RCS). Compared with NT, DT contributes to the rapid increase of SOC and AOC of each soil layer in the early reclamation period, and DST is helpful to maintain higher SOC and AOC contents of each soil layer in the later reclamation period. ST contributes to the accumulation of SOC and AOC in surface soil, but has less effect on SOC and AOC in deep soil compared with DT and DST. ② Different tillage practices have different effects on the stratification ratio (RS) of SOC. In the early reclamation stage, the RS of ST, DT and DST is significantly higher than that of NT. However, NT and ST have high SR in the later reclamation period, and the RS of DT and DST decreases significantly. ③ By influencing SOC and AOC accumulation, different tillage practices affect the carbon pool index (ICP) and carbon pool activity index (IA) of each soil layer, thus affecting ICPM. After eight years of reclamation, the ICP, IA and ICPM of each soil layer in ST, DT and DST are higher than those of NT. DST has the highest ICP, IA and ICPM due to its accumulation of the highest SOC and AOC. DT promotes the mineralized decomposition of SOC due to its long-term over-ploughing, resulting in lower ICP, IA and ICPM than DST. Although ST can increase SOC and ICP in surface layer, its IA is lower than that of DT and DST, resulting in a significant decrease in ICPM. ④ Different tillage methods also affect crop production by affecting soil carbon sequestration. At the early stage of reclamation, the yield increase rate (YIR) and grain yield of ST, DT and DST are all higher than those of NT, DT has the highest yield and YIR, and DST has the highest gain yield and YIR at the late stage of reclamation. The correlation analysis shows that DT contributes to crop production by rapidly increasing the SOC content of whole soil layer at the early stage of reclamation, while at the later stage of reclamation, DST contributes to crop production by increasing the AOC and SOC content of the whole soil layer and reducing the SR of SOC. In conclusion, based on soil carbon sequestration and crop production capacity, DT should be adopted in the early stage of reclamation, DST is a better tillage method in the late stage of reclamation, while NT and ST are not conducive to the rapid improvement of soil carbon sequestration and crop productivity of reclaimed farmland.
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