Soil respiration and carbon balance in fava bean farmland under conservation tillage
XIONG Ying;WANG Long-Chang;ZHAO Lin-Lu;DU Juan;ZHANG Sai;ZHOU Quan;College of Agronomy and Biotechnology,Southwest University,Key Laboratory of Eco-environments in Three Gorges Reservoir Region,Ministry of Education,Engineering Research Center of South Upland Agriculture,Ministry of Education;College of Agriculture,Henan University of Science and Technology;
Soil respiration is an important process in carbon cycling.This study investigated effects of two tillage practices(ridge tillage and traditional tillage)and straw mulching at 0,3750,or 7500 kg straw dry matter/ha on soil respiration of fava bean farmland.Six treatments applied were:traditional tillage without straw mulching(T),ridge tillage without straw mulching(R),traditional tillage+straw mulching at 3750kg/ha(TS1),ridge tillage+straw mulching at 3750kg/ha(RS1),traditional tillage+straw mulching at 7500kg/ha(TS2),and ridge tillage+straw mulching at 7500kg/ha(RS2).Soil respiration properties and carbon balance in dry-cropped farmland with a triple intercropping system of fava bean,maize,and sweet tomato were evalua-ted during the crop growth period,in a region of southwest China known as the purple hilly region.This study identified seasonal changes in soil respiration rate reflecting crop growth,with a peak in the middle of the fava bean growth cycle,and with a range from 0.885-10.213μmol/(m~2·s)in cropped soils,respectively.The soil respiration rates of the different treatments ranked TS2RS2RS1TS1TR [4.096,3.780,3.441,3.104,2.850,2.439μmol/(m~2·s),respectively].Ridge tillage reduced soil respiration in fava bean farmland,whereas straw mulching treatment resulted in increased respiration corresponding to straw mulching levels.In soil planted with fava bean,the respiration rate at different crop growth stages ranked ripeningseedlingseed filling branching flowering and podding.Soil respiration during flowering,filling and podding stages contributed 50% of the total soil respiration.The contribution of root respiration to total soil respiration was 49.12%(range 37.02%-60.64%)when measured by a root biomass regression equation,but was38.62%(range 19.49%-52.3%)when measured by root exclusion.The farmland system sequestered carbon during the life cycle of the fava bean crop with a net carbon sink ranging from 857.26 to 2236.25 kg C/(ha·yr).The treatments RS2,TS2,RS1,TS1,R increased carbon sequestration by 160.86%,101.44%,30.78%,47.63% and 110.41%,respectively(P0.05),compared to the treatment T.This study indicated that ridge tillage and straw mulching conservation improved carbon sequestration in a fava bean farmland ecosystem,and the best treatment was RS2(ridge tillage+straw mulching at 7500kg/ha).
【Fund】： 国家自然科学基金项目(31271673);; 公益性行业(农业)科研专项(201503127)资助
【CateGory Index】： S643.6
【CateGory Index】： S643.6