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Lanzhou University (2022)

Soil Greenhouse Gas Emission from Sown Pastures in Hexi Oasis

宁娇

Titre : Soil Greenhouse Gas Emission from Sown Pastures in Hexi Oasis

Auteur : 宁娇

Grade : Doctoral Dissertation 2022

Université : Lanzhou University

Résumé partiel
Sown pasture produces 35.4%of the world’s livestock products and support 13%of the population ;livestock products of grass-feeding account for 85.4%of global livestock products and emit 68%of agricultural GHGs.Increasing population and improving living standards have rigidly increased the demand for cultivated grassland-livestock production systems.Increasing the productivity of sown pasture and reducing environmental footprints such as GHG emissions are important of the"carbon neutrality and emission peak"strategy.To this end,the effects of forage types,nitrogen application and utilization patterns on soil GHG emissions from sown pasture were studied in Hexi Oasis.The main findings are as follows :(1)Characteristics and factor analyses of soil GHG emissions for eight kinds of forage.In 2014,eight kinds of forage with two life forms of perennial and annual,two nitrogen-fixing kinds of legume and grass,and two photosynthetic kinds of C3 and C4.For the grass yield:sorghum sudan hybrid(Sorghum bicolor×S.sudanenese,S)>corngrass(Zea mays×Zea Mexicana.,C)and alfalfa(Medicago sativa,A)>maize(Zea mays,M)>common vetch(Vicia sative,V),barley(Hordeum vulgare,B),wheat(Triticum aestivum,W)=rye(Secale cereale,R),for the crude protein(CP)content:A,V>C,B,W,R>M,S and for CP yield:A>S,C>V,M>B,W,R.Cumulative soil CH4flux during the growth period A,S,C,W>B,W,R>V.Cumulative N2O emissions:A,S,C,M>B,W,R>V.Soil GHG emissions per unit of hay yield were 0.96–1.62 kg/kg hay,respectively were:M,W≥B,R≥A,V≥C≥S.Soil GHG emissions per unit of CP yield were6.89-14.58 kg/kg CP,respectively were:M≥R,W≥B>C,S>A,V.Soil GHG emissions per unit of metabolic energy(ME)yield were 0.100-0.200 kg/MJ ME,respectively were:B,W,R>M>A,V,C,S.Soil CO2 emission flux and CH4 uptake flux showed a"hump-shaped"curve with the changes of hay and CP yield,soil cumulative CO2 emission was significantly positively correlated with cumulative CH4uptake and cumulative N2O emission during the growth period.Soil CO2 emission,CH4 absorption and N2O emission had positive correlations with soil temperature(ST),available nitrogen(AN),p H,soil organic carbon(SOC)and total nitrogen(TN),but had negative correlations with soil water content(SWC).The Q10 value of soil respiration to temperature change was higher in grass pasture than in legumes pasture.The contribution of ST to soil respiration was 72.79%,the contributions of ST and AN to soil respiration respectively were75.54%and 8.53%in legume pasture.The contributions of ST and p H to soil CH4 absorption respectively were 70.39%and 2.65%in grass pasture and 66.35%and 7.22%in legume pasture.The contributions of ST and SWC to soil N2O emission respectively were 71.95%and 6.24%in grass pasture,the contributions of ST and AN to soil N2O emission respectively were51.18%and 18.96%in legume pasture.

Mots clés : sown pasture ;productivity;greenhouse gas ;nitrogen fertilizer ;grazing;emission intensity ;soil physical and chemical properties ;

Présentation (CNKI)

Page publiée le 19 octobre 2022