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 maizeand 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)、玉米//大豆间作(MI)2种种植模式下, 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: 在不同施磷梯度下, 玉米大豆间作显著提高了红壤有机碳储量、土壤活性有机碳组分含量、土壤碳固存量和固存速率, 显著促进了红壤的有机碳固存。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%;土壤有机碳含量(SOC)分别提高15.3%、34.4%、28.9%、25.5%, 土壤活性有机碳(LOC)含量分别提高20.1%、54.7%、39.1%、32.1%;土壤微生物量碳(MBC)分别提高26.5%、48.8%、38.5%、49.7%;土壤碳固存量分别提高42.6%、49.3%、42.8%、46.1%;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%。同时, 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, 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60-90 P2O5 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 investigate the effects of intercropping on organic carbon sequestration in red soil and its response to phosphorus application, this study was based on a 7-year continuous field positioning experiment in a typical low-phosphorus red soil region of Yunnan. Four phosphorus fertilizer gradients were set: 0 (P0), 60 (P60), 90 (P90), and 120 (P120) kg∙P2O5∙hm-2. The study systematically analyzed changes in soil organic carbon storage, soil organic carbon components, carbon sequestration amount, carbon sequestration rate, soil carbon pool activity index, and carbon pool management index under two planting patterns: maize monoculture (MM) and maize//soybean intercropping (MI), as well as their responses to different phosphorus fertilizer application rates. The results indicate that under different phosphorus application gradients, maize//soybean intercropping significantly enhances the organic carbon storage, the content of soil active organic carbon components, the soil carbon sequestration amount and rate in red soil, and notably promotes the organic carbon sequestration in red soil. Under P0, P60, P90, and P120 conditions, compared to corresponding monocultures, intercropping increased soil organic carbon storage (SOCs) by 21.3%, 31.8%, 30.1%, and 31.1%, respectively; soil organic carbon content (SOC) by 15.3%, 34.4%, 28.9%, and 25.5%, respectively; labile organic carbon (LOC) content by 20.1%, 54.7%, 39.1%, and 32.1%, respectively; microbial biomass carbon (MBC) by 26.5%, 48.8%, 38.5%, and 49.7%, respectively; soil carbon sequestration by 42.6%, 49.3%, 42.8%, and 46.1%, respectively; the activity index (AI) of red soil carbon pool by 9.0%, 36.1%, 20.3%, and 14.2%, respectively; and the carbon pool management index (CPMI) by 25.7%, 86%, 54.5%, and 39.7%, respectively. Simultaneously, the yields of intercropped maize increased by 38.6%, 46.1%, 24.2%, and 6.5%, respectively.Regardless of whether in monoculture or intercropping patterns, the rational application of phosphorus fertilizer significantly enhanced the organic carbon sequestration in red soil, with P90 showing the highest effect. The intercropping's promotion of red soil carbon sequestration was most pronounced at P60. In conclusion, on low-phosphorus red soil, maize//soybean intercropping significantly promotes soil carbon sequestration and increases maize yield advantages, with the intercropping advantage being optimal at 60-90 P2O5 kg∙hm-2. This is one of the optimized planting models for promoting maize yield increase and achieving green and low-carbon goals in the red soil region of Southwest China.

     

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