太湖地区长期施肥条件下水稻-油菜轮作生态系统净碳汇效应及收益评估

以太湖地区水稻-油菜轮作系统长期施肥处理试验田为研究对象，利用历年作物产量、凋落物固碳和农田CO₂排放等实测资料，以及生态系统的物质投入和管理投入等调查资料，估算了该系统的年碳平衡和经济收益.结果表明：不同施肥处理的年碳汇量在0.9～7.5 t C·hm^-2·a^-1，有机无机肥配施的净碳汇量是单施化肥的3倍.系统物质投入的碳成本在0.37～1.13 t C·hm^-2·a^-1，人工管理的碳成本在1.69～1.83 t C·hm^-2·a^-1，年度经济收益在5.8×10³～16.5×10³ CNY·hm^-2·a^-1，有机无机肥配施下的经济效益是单施化肥下的1.1倍.与单施化肥相比，有机无机肥配施单位碳汇的边际成本为217.1 CNY·t^-1 C，与欧盟碳交易市场的碳价格每吨20欧元相近.与单施化肥相比，有机无机肥配施下生态系统不仅生产力较高，而且表现出更高的碳汇效应和经济收益.

An evaluation of net carbon sink effect and cost/benefits of a rice-rape rotation ecosystem under long-term fertilization from Tai Lake region of China

Taking a long-term fertilized rice-rape rotation system in Taihu Lake as test objective, its annual C balance and economic benefit were estimated, based on the measurement of past years grain yield, litter C content, and field CO2 emission as well as the investigation of material and management inputs. The calculated annual C sink under different fertilizations ranged from 0.9 t C·hm-2·a-1 to 7.5 t C·hm-2·a-1, and the net C sink effect under combined inorganic/organic fertilization was three folds as that under chemical fertilization. The C cost of material input ranged from 0.37 t C·hm-2·a-1 to 1.13 t C·hm-2·a-1, and that of management input ranged from 1.69 t C·hm-2·a-1 to 1.83 t C·hm-2·a-1. The annual economic benefit ranged from 5.8×103 CNY·hm-2·a-1 to 16.5×103 CNY·hm-2·a-1, and was 2.1 times higher under combined fertilization than under chemical fertilization. Comparing with that under chemical fertilization, the marginal cost for per ton C sink under combined inorganic/organic fertilization was estimated as 217.1 CNY· t-1 C, very close to the C price of 20 Euro·t-1 C in the EU. In sum, under combined inorganic/organic fertilization, this rice paddy ecosystem could not only have higher productivity, but also present greater net C sink effect and higher economic benefit, compared with under chemical fertilizer fertilization.