玉米||大豆间作对红壤有机碳固存的影响及其施磷响应

Effect of maize and soybean intercropping on organic carbon sequestration in red soil and its response to phosphorus application

    摘要
  • 摘要: 为探究间作对红壤有机碳固存的影响及其施磷响应, 本研究基于云南典型低磷红壤区连续7年的田间定位试验, 设置0 (P0)、60 (P60)、90 (P90)、120 (P120) kg(P2O5)∙hm−2 4个磷肥梯度, 系统分析玉米单作(MM)和玉米||大豆间作(MI)种植模式下, 土壤有机碳储量、土壤有机碳组分、碳固存量、碳固存速率、土壤碳库活度指数和碳库管理指数的变化及其对不同磷肥施用量的响应。结果表明: 种植模式和施磷处理对红壤有机碳固存具有显著的协同促进作用。在不同施磷梯度下, 玉米||大豆间作显著提高了红壤有机碳固存能力, 在P0、P60、P90、P120下, 与对应单作相比, 间作土壤有机碳储量(SOCs)分别提高21.3%、31.8%、30.1%、31.1%; 土壤固存量土壤碳固存量分别提高42.6%、49.3%、42.8%、46.1%; 其中均以P60增幅最高。在不同施磷梯度下, 玉米||大豆间作显著提高了红壤碳库活性和稳定性, 在P0、P60、P90、P120下, 与对应单作相比, 红壤碳库活度指数(AI)分别增加9.0%、36.1%、20.3%、14.2%, 碳库管理指数(CPMI)分别增加25.7%、86%、54.5%、39.7%。其中均以P60增幅最高。在不同施磷梯度下, 玉米||大豆间作显著增加了玉米产量, 在P0、P60、P90、P120下, 与对应单作相比, 间作玉米产量分别提高38.6%、46.1%、24.2%和6.5%。无论单作还是间作模式, 合理施用磷肥均显著提高了红壤有机碳固存量, 其中以P90最高, 间作促进红壤碳固存的效应以P60增幅最高。综上, 在低磷红壤上, 玉米||大豆间作具有显著促进土壤碳固存、增加玉米产量优势, 间作优势在施磷(P2O5) 60~90 kg∙hm−2最好, 是促进西南红壤区玉米增产和绿色低碳的优化种植模式之一。

     

    Abstract: To explore the effect of intercropping on organic carbon sequestration in red soil and its response to phosphorus fertilization, this study was based on a 7-year continuous field experiment in a typical low-phosphorus red soil area of Yunnan, China. Four phosphorus fertilizer gradients were established: 0 (P0), 60 (P60), 90 (P90), and 120 (P120) kg∙P2O5∙hm-2. The study systematically analyzed the changes in soil organic carbon stock (SOCs), soil organic carbon fractions, carbon sequestration amount, carbon sequestration rate, soil carbon pool activity index (AI), and carbon pool management index (CPMI), as well as their responses to different phosphorus fertilization levels, under two planting patterns: maize monocropping (MM) and maize//soybean intercropping (MI).The results showed that planting pattern and phosphorus application had a significant synergistic promotion effect on red soil organic carbon sequestration. Under different phosphorus application gradients, maize//soybean intercropping significantly improved the organic carbon sequestration capacity of red soil. Compared with the corresponding monocropping, the intercropped soil organic carbon stock (SOCs) increased by 21.3%, 31.8%, 30.1%, and 31.1% under Under P0, P60, P90, and P120, respectively; the soil carbon sequestration amount increased by 42.6%, 49.3%, 42.8%, and 46.1%, respectively. The highest increase in both indices was observed at P60.Under different phosphorus application gradients, maize//soybean intercropping significantly improved the activity and stability of the red soil carbon pool. Compared with the corresponding monocropping, the red soil carbon pool activity index (AI) increased by 9.0%, 36.1%, 20.3%, and 14.2% under Under P0, P60, P90, and P120, respectively, and the carbon pool management index (CPMI) increased by 25.7%, 86%, 54.5%, and 39.7%, respectively. The highest increase in both indexes was observed at P60.Under different phosphorus application gradients, maize//soybean intercropping significantly increased maize yield. Compared with the corresponding monocropping, the intercropped maize yield increased by 38.6%, 46.1%, 24.2%, and 6.5% under P0, P60, P90, and P120, respectively. Regardless of the monocropping or intercropping pattern, rational phosphorus application significantly improved organic carbon sequestration in red soil, with the highest effect observed at P90. The promoting effect of intercropping on red soil carbon sequestration was highest at P60.In summary, maize//soybean intercropping on low-phosphorus red soil offers significant advantages in promoting soil carbon sequestration and increasing maize yield. The intercropping advantage is optimal at a phosphorus application rate of 60-90 P2O5∙hm−2. This system is one of the optimized planting modes for increasing maize yield and promoting green, low-carbon development in the red soil region of Southwest China.

     

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