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Lanzhou University (2021)

Productivity and Evaluation of Sown Grassland-Sheep Grazing System in Hexi Oasis

娄珊宁

Titre : Productivity and Evaluation of Sown Grassland-Sheep Grazing System in Hexi Oasis

Auteur : 娄珊宁

Grade : Doctoral Dissertation 2021

Université : Lanzhou University

Résumé partiel
Grazing is one of the economic,efficient and green utilization of grassland.Sown grassland is one of the main food production bases in the world.The grazing utilization of sown grassland is an effective way to ensure the security of national food and ecology.Researches on grazing management of sown grassland is insufficient in China.Hence,a sown grassland-sheep grazing system was established in the Hexi Oasis.Based on 9years of grazing experiments,the characteristics of plant and livestock productivity and their formation mechanisms were studied,and a comprehensive evaluation was made from the perspective of the ecosystem.The main findings are as follows:1 The effect of grazing on the forage production of sown grassland(1)The effect of rational grazing on forage yieldThe annual average DM yields of barley,rye,wheat,alfalfa+tall fescue,alfalfa+bromus inermis,and alfalfa+bromus inermis+tall fescue pasture under grazing,were5.61、11.33、5.20、4.25、8.98 and 4.71 t/ha,respectively ;the CP yields were 1.50,1.40、1.38、0.65、1.33,and 0.79 t/ha,respectively ;the metabolizable energy(ME)yield were 146.44,147.4,136.28,31.77,54.54 and 40.15 GJ/ha,respectively.The mean DM yield for barley,rye and wheat monoculture pasture,alfalfa+tall fescue,alfalfa+bromus inermis and alfalfa+bromus inermis+tall fescue mixed pasture,varied by19.38%,46.10%,-11.79%(P>0.05),-3.44%(P>0.05),13.97%(P>0.05)and41.90%,respectively ;mean crude protein(CP)yield changed by 204.32%,432.79%,324.38%,-2.03%(P>0.05),27.77%and 42.40%,respectively ;the ME yield changed by 200.55%,239.91%,192.93%,-0.49%(P>0.05),24.73%and 117.93%,respectively.Interannual fluctuations in forage production were greater for wheat,alfalfa+tall fescue,and alfalfa+bromus inermis pasture.Grazing has a greater contribution rate to increase the forage production for annual pasture.The forge production of perennial pasture was affected by the interaction effect of utilization strategy and utilization years.(2)The effect of grazing on forage qualityThe annual average crude protein(CP)concentrations of barley,rye,wheat,alfalfa+tall fescue,alfalfa+bromus inermis,and alfalfa+bromus inermis+tall fescue grassland,were 11.53%,10.73%,10.60%,11.77%,9.63%and 10.43%DM,respectively ;neutral detergent fiber(NDF)concentrations were 47.28%,39.26%,47.61%,47.99%,41.63%and 47.06%DM,respectively ;acid detergent fiber(ADF)concentrations were 23.26%,20.72%,25.75%,22.05%,18.89%and 26.13%DM,respectively ;dry matter digestibility(DMD)were 71.72%,74.19%,68.55%,70.78%,72.76%and 68.84%DM,respectively.Compared to grassland for hay harvest,annual variation rate of CP concentrations for grazing barley,rye,wheat,alfalfa+tall fescue,alfalfa+bromus inermis,and alfalfa+bromus inermis+tall fescue mixed pasture,increased by 0.83%,49.26%,24.51%,0.83%(P>0.05),46.03%and13.63%(P>0.05),respectively ;NDF concentrations changed by(+indicates increase,and–indicates decrease)0.80%(P>0.05),-18.61%、8.89%,0.80%(P>0.05),-20.51%and 7.91%,respectively ;ADF concentrations changed-0.99%,-29.78%,9.27%(P>0.05),-0.99%(P>0.05),-31.64%and 10.17%(P>0.05),respectively ;DMD changed 0.24%(P>0.05),9.18%,-2.46%(P>0.05),0.24%(P>0.05),10.26%and-2.52%(P>0.05),respectively.Hence,the annual variations of quality for perennial pasture was greater than that for annual pasture.Grazing is an effective strategy to improve the forage quality of annual pasture.There was a significant interaction effect of grazing and utilization years on the forage quality of perennial pasture.

Mots clés : Annual pasture ;perennial pasture ;forage quality ;water use efficiency ;nitrogen use efficiency ;grazing behavior ;integrated crop-livestock production system ;

Présentation (CNKI)

Page publiée le 15 novembre 2021