长期不同施肥模式对南方双季稻田生态系统净碳汇效应和经济收益的影响

Effects of different long-term fertilization patterns on net carbon sink effect and economic benefits in double cropping rice paddy ecosystem in southern China

施肥措施与稻田生态系统净碳汇效应、经济收益的关系密切。本研究以长期(35年)定位施肥试验田为平台,分析了单独施用化肥(MF)、秸秆还田+化肥(RF)、30%有机肥+70%化肥(OM)和无肥对照(CK)4种不同施肥模式对我国南方双季稻田耕层土壤固碳速率、碳密度、年碳汇平衡和经济收益的影响。研究表明:不同施肥处理双季稻田耕层土壤碳库变化范围为216.02~866.74 kg·hm^(-2)·a^(-1),OM处理土壤碳年变化量显著高于MF、RF和CK处理;双季稻田土壤固碳速率为51.5~650.7 kg·hm^(-2)·a^(-1),表土碳密度为55.64~78.42 t·hm^(-2),各施肥处理高低顺序均为OM>RF>MF>CK。各施肥处理双季稻田生态系统水稻的碳吸收为4.42~9.32 t C·hm^(-2)·a^(-1),其高低顺序为OM>RF>MF>CK;与MF处理相比,OM和RF处理稻田土壤净碳汇量分别提高了27.6%和13.6%。各施肥处理双季稻田生态系统的碳成本物质投入变化范围为1.49~2.17 t C·hm^(-2)·a^(-1),年经济收益变化范围为1.30×10^(3)~7.83×10^(3)元·hm^(-2)·a^(-1),其高低顺序为RF>OM>MF>CK;OM、RF和MF处理双季稻田生态系统经济效益的净收益均显著高于CK处理。总之,长期施用有机肥、秸秆还田配施化肥措施均有利于增加双季稻田土壤固碳速率、碳汇效应和经济收益,是提高南方双季稻田土壤有机碳贮量的施肥模式。

There is close relationship between fertilizer managements and net carbon(C)sink effect,economic benefits in rice paddy ecosystem.Based on a long-term(35-year)field experiment,we analyzed the effects of different fertilization patterns on soil C sequestration rate,C density of topsoil,annual C balance,and economic benefits in the double cropping rice paddy in southern China.There were four fertilization treatments,chemical fertilizer alone(MF),rice straw and chemical fertilizer(RF),30%organic manure and 70%chemical fertilizer(OM),and without any fertilizer input as a control(CK).The results showed that soil C pool in the double cropping rice paddy field under different fertilization treatments changed from 216.02 to 866.74 kg·hm^(-2)·a^(-1),and soil C pool under OM treatment were significantly higher than that of MF,RF and CK.The soil C sequestration rates in the double cropping rice paddy field under different fertilization treatments ranged from 51.5 to 650.7 kg·hm^(-2)·a^(-1),and that of C density of topsoil was from 55.64 to 78.42 t·hm^(-2).The order of soil C sequestration rates and C density of topsoil was OM>RF>MF>CK.The change range of C adsorption in the double cropping rice paddy field ecosystem was from 4.42 to 9.32 t C·hm^(-2)·a^(-1),with an order of OM>RF>MF>CK.Compared with the MF treatment,soil net C sink under OM and RF treatments increased by 27.6%and 13.6%,respectively.The change range of C cost material input ranged from 1.49 to 2.17 t C·hm^(-2)·a^(-1),and that of annual economic benefits was from 1.30×10^(3)to 7.83×10^(3)yuan·hm^(-2)·a^(-1)with an order of RF>OM>MF>CK.The net income of economic benefits of OM,RF and MF treatments were significantly higher than that of CK.Generally,soil C sequestration rate,C sink effect and annual economic benefits were increased by the long-term application of organic manure and rice straw returning together with chemical fertilizer,which could increase soil organic carbon storage in the double cropping rice paddy field of southern China.