Abstract: 【Objective】To evaluate the effects of different mowing frequencies on the contents of Ca,Fe,Zn and amino acids in Leymus chinensis leaves in natural grassland. And to find a more scientific and reasonable mowing method.【Methods】The experiment was carried out in a random block design. The levels of Ca,Fe,Zn,and 14 amino acids in Leymus. chinensis leaves were measured during the course of 19 years of mowing at various frequency.【Results】Ca content in Leymus chinensis leaves mowed every two years and rested for a year,once a year,and twice a year increased by 13.6%,21.8%,and 11.8%,respectively,when compared to no mowing. The difference was statistically significant（P<0.05）. Without mowing and mowed at varied frequency,there was no significant difference（P>0.05）in Fe and Zn concentration in Leymus chinensis leaves. The total amount of 14 amino acids increased by 30.95%,40.19% and 33.76% in Leymus chinensis leaves mowed one year and rest for a year,mowed every two years and rest for a year,and mowed once a year,with satistically significant（P<0.05）differences compared with no mowing. Under different mowing frequencies,the content of Ca in Leymus chinensis leaves was the highest when mowed once a year,followed by mowing every two years and rest for a year. The total amount of the 14 amino acids was highest in mowing every two years and rest for a year,followed by mowing every year.【Conclusion】Mowing once a year and mowing every two years and resting one year were scientific and reasonable approaches for improving Leymus chinensis grassland quality.

Key words: Natural Leymus chinensis grassland, Mowing frequencies, Calcium, Ferrite, Zinc, Amino acid