Effects of Nitrogen and Phosphorus Fertilization on Yield of Medicago sativa-Leymus chinensis Mixed Grassland
A field experiment was conducted in mildly saline-alkaline areas of central and western Inner Mongolia to investigate the effects of nitrogen and phosphorus fertilization on yield stability of Medicago sativa-Leymus chinensis mixed grassland,relevant to dryland agriculture.The study aimed to elucidate how fertilization influences the plant community characteristics of the mixed grassland.The results showed that:(1)Nitrogen and phosphorus addition significantly increased the yield of both M.sativa and L.chinen-sis in the mixed grassland.In both September 2021 and June 2022,the total yield of M.sativa and L.chi-nensis in the mixed grassland under fertilization treatments was significantly higher than that in the control group(P<0.05).The highest total yield was observed under combined nitrogen and phosphorus addition,with the total yield of M.sativa and L.chinensis reaching 3.57 t/hm² and 4.55 t/hm²,respectively,repre-senting increases of 59.38%and 85.71%compared to the control.(2)Fertilization treatments altered the relative yield contribution of M.sativa and L.chinensis.In June 2021,L.chinensis exhibited a higher yield proportion(56%)than M.sativa under nitrogen addition alone.However,under phosphorus addi-tion and combined nitrogen and phosphorus addition,M.sativa became the dominant species,contributing 56%and 54%of the total yield,respectively.(3)The faster regrowth rate of M.sativa compared to L.chinensis resulted in a significant shift in yield proportion following harvest.By September 2021,M.sativa exceeded 76%of the total yield in all treatments,and this dominance further increased to over 87%by June 2022.In conclusion,nitrogen and phosphorus fertilization promoted yield increases in M.sativa and L.chinensis mixed grassland.Notably,M.sativa emerged as the dominant species,influencing overall bio-mass production and potentially contributing to yield stability in the mixed grassland.
Artificial grasslandFertilizationForage yieldMixed sowingSaline-alkali land
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