湖南省稻田表层土壤固碳潜力模拟研究

稻田土壤有机碳的储存对于缓解大气温室效应具有不可忽视的作用。我国作为水稻产量最大的国家,迫切需要掌握稻田生态系统固碳现状及相应固碳措施。文章利用自主建立的土壤有机碳模型对湖南省稻田生态系统不同有机物投入方式下土壤有机碳的变化进行了模拟研究。结果表明,常规施肥(现状)方式下稻田表层土壤有机碳的饱和固碳量为39.75～64.90th/m₂,半数模拟点已基本饱和,其余点仍具有3.38～4.19th/m₂的固碳潜力;50%秸秆还田效果低于常规施肥方式,而50%秸秆+绿肥效果高于常规方式(平均高10.94th/m₂);全量秸秆还田(冬闲)情况下稻田表层土壤饱和固碳量在55.57～94.25th/m₂之间,与稻田现有碳储量比较有4.15～33.46th/m₂的潜在提高幅度。如果全量秸秆还田结合冬季种植绿肥,土壤饱和固碳量则可以在稻田土壤现有碳储量的基础上平均提高65.77%。模拟结果还表明,湖南稻田土壤中,每年投入1th/m₂的新鲜有机碳可最终形成土壤有机碳饱和固碳量约12th/m₂。研究表明,稻田土壤的饱和固碳量可以通过人为措施进行调控,增加有机物质的投入量(秸秆还田)和冬季绿肥种植是提高稻田土壤固碳能力的有效途径。

Simulation of Carbon Sequestration Potential of Paddy Soils in Hunan Province, China

Organic carbon sequestration of paddy soils plays an important role in mitigating the global warming.China is the largest country of rice production in the world,and for UNFCCC,carbon sequestration status,potential and corresponding measures to enhance the carbon stocks of rice cultivation system should be investigated independently and urgently.With SCNC model we developed independently,this paper simulated the potential of carbon sequestration in paddy soils in Hunan province,and the aim is to illustrate the carbon sequestration potential of paddy soils and find the countermeasures to improve the current conditions.The simulated results showed that saturated carbon storage of paddy soils ranged from 39.75-64.90t/ha under conventional fertiliza-tion,and half of the modeling plots have been saturated,while for the remaining plots,the carbon sequestration potential ranged from 3.38-4.19t/ha.The saturated carbon storage under 50% of straw incorporation was lower than the conventional fertilization,but the storage of 50% straw incorporation combined with green manure plantation treatment was higher than the conventional fertilization(increased by 10.54t/ha averagely).The saturated carbon storage with 100% straw incorporation ranged from 55.57-94.25t/ha,compared with current carbon storage,the potential in-crement was 4.15-33.46t/ha.The saturated carbon storage of 100% straw combined with green manure incorporation was 65.77% higher than that of current carbon storage.The simulation results also showed that the saturated carbon storage would hit 12t/ha under the condition of incorporating 1t/ha fresh organic material annually into paddy field of Hunan Province.Therefore,increasing the amount of organic material and planting green manure are effective measures to enhance carbon storage of paddy field.