测土配方施肥对湖北省N2O减排的贡献

为弄清测土配方施肥项目实施后对氧化亚氮(N_2O)排放产生的影响及其带来的经济效益.本研究通过比较传统施肥和测土配方推荐施肥的农田氮(N)投入量,依据《2006年IPCC国家温室气体清单指南》方法,分别估算了农田N_2O的直接排放和间接排放.结果表明,测土配方施肥项目从2004年开始实施至2013年的10年时间里,共减少氮肥的施用量74.39×104t(折纯N),作物产量增加1898.05×104t;10年里共减少N_2O排放总量为2.24×104t,其中由氮肥施用量减少带来的N_2O减排量为1.57×104t,作物产量提高带来的N_2O减排量为0.67×104t;湖北省不同区域的N_2O减排量与该地区项目实施面积密切相关,项目实施10年来襄阳市N_2O减排总量最大,为0.31×104t,其次是荆州市,减排量为0.26×104t,神龙架林区N_2O减排总量最小,仅为0.0034×104t;不同作物对N_2O减排的贡献以玉米减排总量最大,为0.54×104t,占减排总量的24.17%,其次为水稻,减排量为0.49×104t,芝麻减排总量最小,仅0.018×104t.按照湖北省碳交易市场最新交易价格25元·t-1C来计算,湖北省实施测土配方施肥项目10年来仅N_2O减排所带来效益可达1.74亿元.测土配方施肥项目不仅在湖北省粮食增产上有重要贡献,对减少N_2O排放也有重要贡献,并带来一定的经济效益.

Contribution of soil testing for formulated fertilization to N2O mitigation in Hubei Province

This study was aimed to understand the effects of soil testing for formulated fertilization on N₂O emission and economic benefit in Hubei Province. Following the IPCC(2006) guidelines and methods, the N₂O mitigation was estimated from the farmland N inputs of conventional fertilization and recommended fertilization. The results showed that, in the past 10 years, the soil testing for formulated fertilization project decreased N application by 7.44×10⁵ tons, increased yield by 1.90×10⁷ tons and mitigated 2.24×10⁴ tons N₂O. The mitigation from reduced N fertilization and increased yield were 1.57×10⁴ tons and 6.7×10³ tons, respectively. N₂O mitigation was closely related to the study area. The highest N₂O mitigation was found in Xiangyang, with a reduction of 3.1×10³ tons. Jingzhou was the second largest area of mitigated N₂O, about 0.26×10⁴ tons. Shennongjia was the lowest, only 34 tons. The contributions of different crops to the N₂O mitigation were different. Corn was the leading N₂O mitigation crop which reached to 5.4×10³ tons and accounted for 24.17% of total contribution, followed by rice and sesame. According to the latest price in Hubei Carbon Trading Market, soil testing for formulated fertilization has benefited 174 million yuan from the N₂O mitigation in past 10 years. Soil testing for formulated fertilization project plays an important role not only in grain production, but also in N₂O mitigation, and brings economic benefits.