不同轮耕模式对豫北农田土壤固碳及碳库管理指数的影响

Effects of tillage rotation modes on soil carbon sequestration and carbon pool management index of farmland in northern Henan

  • 摘要: 为探究不同轮耕模式对豫北农田土壤固碳及碳库管理指数的影响, 本研究在豫北潮土区, 于2016—2020年小麦季以3年为一个轮耕周期, 设置5个处理: 连续旋耕(RT-RT-RT)、深耕-旋耕-旋耕(DT-RT-RT)、深耕-旋耕-浅旋耕(DT-RT-SRT)、深耕-浅旋耕-浅旋耕(DT-SRT-SRT)、深耕-浅旋耕-旋耕(DT-SRT-RT)。测定并分析了2019年和2020年0~50 cm土层土壤容重、总有机碳(SOC)、易氧化有机碳(LOC)、稳态有机碳(NLOC)含量及有机碳储量和碳库管理指数。结果表明, 各轮耕处理均能降低0~40 cm土层的土壤容重。在0~20 cm土层, DT-SRT-SRT处理的SOC、LOC和NLOC含量最高, 分别为11.54 g∙kg−1、3.31 g∙kg−1和8.30 g∙kg−1; 而相较于RT-RT-RT处理, DT-SRT-RT处理显著增加10~40 cm土层SOC、LOC和NLOC含量; 且各轮耕处理降低了LOC/SOC, 但提高了NLOC/SOC, 尤其是20~40 cm土层, 最高增长7.5%。试验期内, 各轮耕处理均能提高0~40 cm土层土壤有机碳储量, 2019年0~30 cm土层, DT-SRT-SRT处理有机碳储量最高, 为36.64 Mg∙hm−2; 但在2019和2020年, 0~40 cm土层, DT-SRT-RT处理的有机碳储量均为最高, 与RT-RT-RT处理相比分别提高12.8%和9.7%。随耕作年限的不同土壤碳库管理指数(CPMI)呈现出一定的差异, 2019年, DT-SRT-RT处理显著降低了0~40 cm土层中的活度指数, CPMI相对较低, 最高降幅为4.3%。而2020年, DT-SRT-RT处理显著提高了0~40 cm土层的碳库指数和CPMI, CPMI最高为108.5。综合以上分析, 深耕-条旋耕-旋耕处理显著降低了土壤容重, 提高SOC、LOC和NLOC, 增加0~40 cm土层有机碳储量, 具有明显的固碳效应。

     

    Abstract: To explore the effects of different tillage rotation modes on soil carbon sequestration and carbon pool management index of farmland in northern Henan, a field experiment comprising five treatments with different tillage modes was carried out during wheat seasons from 2016 to 2020 in fluvo-aquic soil in northern Henan. The treatments were: 1) continuous rotary tillage (RT-RT-RT, CK); 2) deep tillage-rotary tillage-rotary tillage (DT-RT-RT); 3) deep tillage-rotary tillage-shallow rotary tillage (DT-RT-SRT); 4) deep tillage-shallow rotary tillage-shallow rotary tillage (DT-SRT-SRT); 5) deep tillage-shallow rotary tillage-rotary tillage (DT-SRT-RT). Soil bulk density, soil organic carbon (SOC), liable organic carbon (LOC), non-liable organic carbon (NLOC), organic carbon storage, and carbon pool management index (CPMI) in 0–50 cm soil layers were measured and analyzed. The results showed that the soil bulk density in the 0–40 cm soil layer decreased under rotation tillage treatments. In the 0−20 cm soil layer, the SOC, LOC, and NLOC contents, with values of 11.54 g∙kg−1, 3.31 g∙kg−1, 8.30 g∙kg−1, respectively, were the highest under DT-SRT-SRT and were significantly higher than those under RT-RT-RT. Compared with those under RT-RT-RT, the SOC, LOC and NLOC contents in the 10−40 cm soil layer were significantly higher under DT-SRT-RT. The rotation tillage treatments reduced LOC/SOC but increased NLOC/SOC, especially in the 20−40 cm soil layer; the highest increment was 7.5%. During the experimental period, each rotation tillage treatment increased the soil organic carbon storage in the 0−40 cm soil layer. In 2019, the organic carbon storage in the 0−30 cm layer was highest under DT-SRT-SRT (36.64 Mg·hm−2). However, the organic carbon storage in the 0−40 cm soil layer, which increased by 12.8% and 9.7%, respectively, during 2019 and 2020 compared with that under RT-RT-RT, and was highest under DT-SRT-RT. In 2019, the activity index of carbon pool in the 0−40 cm soil layer under DT-SRT-RT was reduced. The CPMI was relatively low, with a maximum reduction of 4.3%. In 2020, DT-SRT-RT significantly increased the carbon pool index and CPMI values in the 0−40 cm soil layer; the highest CPMI was 108.5. Generally, deep tillage-strip rotary tillage-rotary tillage reduced soil bulk density; increased contents of SOC, LOC, and NLOC as well as NLOC/SOC value; and increased the organic carbon storage in 0−40 cm soil layer; therefore, it was suggested as the optimum practice for carbon sequestration of farmland in northern Henan.

     

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