基于温室气体减排的竹林施肥可持续管理方式研究

Sustainable fertilizer management for reduction of greenhouse gases emission in bamboo forest

针对竹林施肥中的温室气体(greenhouse gases,GHG)排放问题,评估不同施肥管理模式对竹林温室气体排放及毛竹生长的综合影响。结合调查统计法、反硝化分解(denitrification-decomposition,DNDC)模型过程模型法和情景分析方法,以2000—2010年间浙江省安吉县毛竹林为案例进行剖析。结果显示,在不同用量有机农家肥和无机氮肥的7种施用情景模式下,有机农家肥能有效增加土壤有机碳含量从而降低土壤CO2净排放量,3倍于常规用量下的有机农家肥可将CO2、N2O 2种温室气体净排放的综合增温潜势(global warming potential,GWP)从1.7t/(hm2·a)降至-11.3t/(hm2·a),具有最高的GHG减排效应;无机氮肥对CO2排放无明显影响但对N2O有明显增排作用,其中3倍于常规用量的高用量无机氮肥模式下GWP较不施肥时高12.2倍,具有最高的GHG增排效应;在维持竹林高产前提下,以高有机肥模式下单位质量竹林生物质增长的同时温室气体净排放量-2.4kg/kg为最小,最有利于减少竹林GHG排放。从温室气体减排效应的竹林可持续发展角度,推广有机农家肥并控制无机含氮化肥施用,可实现产量保证与GHG减排的双重目标。

Excessive fertilizer use has been recognized as a key factor in increasing agricultural and forestry greenhouse gases （ GHG） emission . Previous studies found that proper fertilizer using control strategy can reduce agricultural CO2 , N2 O , CH4 emission , however , influence crop yields as well . Bamboo is an important economic plant in China , which has been intensively cultivated in recent years to satisfy increasing social demands of bamboo products . To maintain rapid growth of bamboo , the fertilizer using amount in bamboo forest is significantly higher than other human-planted forests such as Pinus massoniana and eucalyptus forest . Therefore , it is necessary to explore a sustainable fertilizer management approach which could achieve the optimum balance between low GHG emission and high production in bamboo forest . The purpose of this study is to develop a sustainable fertilizer management approach by estimating the impact of different fertilization practices on GHG emission and biomass production of bamboo forest comprehensively . It is supposed to reduce current GHG emission from bamboo plantation without inhibiting bamboo production . Integrated with the surveys/statistics data , the DNDC （ denitrification-decomposition） biogeochemical model was applied to simulate seven typical fertilization scenarios of a Moso bamboo forest in Anji County , Zhejiang Province during 2000-2010 . The fertilization scenarios were designed by different fertilizer types （ commercial organic compound fertilizer , cow manure , ammonium bicarbonate） and application dosages （ medium , low , high） . Three indicators were adopted for the assessment ：1） the global warming potential （GWP） to assess the total CO 2 and N2 O emission from studied bamboo plantation; 2） the net primary production （ NPP） to assess the bamboo production;3） the GHG emission per bamboo biomass increments （ Cflux/Cbiomass ） . All the indicator values were calculated from the DNDC modeling results . According to the assessment results , manure had the strongest effect on reducing GHG emission by increasing the soil organic carbon （ SOC ） , and the GWP under high amount of commercial organic fertilizer and manure application （ scenario M H） decreased to -11.3 t/（ hm^2·a） while the value under none fertilization condition was 1.7 t/（ hm2. a ） ; the inorganic N fertilizer showed no obvious impact on CO 2 emission but had strong effect on stimulating N2 O emissions , and the high amount of inorganic N fertilizer （ scenario ABH） led to a 12.2 times higher net GWP than the situation without fertilization , which was recognized as the most negative scenario for low-carbon fertilizer management . Under seven fertilization scenarios , the bamboo biomass increments showed no obvious difference compared with the situation without fertilization . However , the NPP under the M scenario （ common amount of commercial organic fertilizer and manure） was slightly higher than other scenarios with the value of 4.71 t/（ hm^2·a） , indicating that organic fertilizers and manure have stronger effect on improving bamboo production . Without inhibiting bamboo production , the high amount of manure application resulted in the lowest net GWP for per net primary production increment （ -2.4 kg/kg） , which had the most significant GHG reduction among all other scenarios . As a consequence , organic fertilizer shows more potential on reducing CO 2 , N2 O emission without decreasing bamboo production . From the GHG emission reduction perspective in sustainable fertilizer management for bamboo forest , advocating organic fertilizer application and reducing inorganic N fertilizer use can be a plausible approach towards the dual objectives of high bamboo production and GHG emission reduction .