青海湖地区高寒草地暖冷放牧季节土壤和牧草营养动态综合评价OA

In this study,three natural grasslands in Halejing Township,Qinghaihu Township and Ganzihe Township of Haiyan County in the Qing-hai Lake region were used as sample plots.Twenty forage samples and 20 soil samples were randomly collected from each plot in the warm season(August)and cold season(November),respectively,with three replicates for each sample.By determining soil nutrients,forage nutrient contents and in vitro fermentation parameters of forage,a comprehensive evalu-ation was conducted on soil nutrients,forage nutritional quality and grassland carrying capacity of the natu-ral grasslands.The results showed that in the warm season,the contents of soil total potassium(TK)and total phosphorus(TP)in grasslands of Halejing Township and Ganzihe Township were significantly higher than those in Qinghaihu Township(P<0.05).The soil ammonium nitrogen(NH₄⁺-N)content in Qinghaihu Town-ship was the highest,and the contents of neutral detergent fiber(NDF),acid detergent fiber(ADF),calcium(Ca)and phosphorus(P)in natural forage were significantly higher than those in Halejing Township.In the cold season,the soil available potassium(AK)content in Halejing Township was relatively high.The con-tents of crude protein(CP),calcium(Ca)and phosphorus(P)in forage from Qinghaihu Township were signifi-cantly higher than those from Ganzihe Township(P<0.05),while the soil NDF and ADF contents in Ganzihe Township were relatively high.For in vitro fermentation parameters of forage,the GP24 h,GP36 h and GP48 h of forage from Qinghaihu Township in the warm season were significantly higher than those from Ganzihe Township(P<0.05),and the concentrations of acetic acid and isobutyric acid were also significantly higher(P<0.05).In the cold season,the GP36 h and GP48 h of forage from Qinghaihu Township were significantly higher than those from Ganzihe Township(P<0.05),and the total volatile fatty acid(TVFA)concentration was significantly higher than that in Halejing Township(P<0.05).In terms of theoretical livestock carrying capacity,the quantitative livestock carrying capacity of grasslands in Halejing Township in the warm season was 4.41%and 2.94%higher than that in Qinghaihu Township and Ganzihe Township,respectively,and the digestible crude protein(DCP)nutritional carrying capacity was 10.77%and 4.94%higher,respectively.In the cold season,the quantitative livestock carrying capacity of grasslands in Halejing Township was 20.38%higher than that in Qinghaihu Township,but the DCP nutritional carrying capacity decreased by 40%,while its quantitative and DCP nutritional carrying capacities were still 5.98%and 29.41%higher than those in Ganzihe Township,respectively.This indicated that Halejing Township had certain advantages in grassland quantitative livestock carrying capacity,but showed certain differences in DCP nutritional carrying capacity.Based on comprehensive nutritional indexes and livestock carrying capacity,it is recommended that grass-land forage in Halejing Township should be preferentially utilized in the warm season,while forage in Qing-haihu Township should be prioritized in the cold season to facilitate the overwintering of yaks.Meanwhile,grassland grazing management strategies should be further optimized in combination with grassland distance and transfer costs..