The accumulating amounts of nutrient element in Trifolium pratense population in different utilization periods

The accumulating amounts of nutrient element in artificial Trifolium pratense population in different utilization period are studied. The results show that the T. pratense populations in different seasons, Mar. to May(Ⅰ), Jun. to Jul. (Ⅱ) and Aug. to Sept. (Ⅲ), the maximum and mean values of accumulating amount of nutrient element usually are Ⅰ＞Ⅱ＞Ⅲ. The accumulating amount of nutrient element increases usually with the prolongation of the growing day of T. pratense population before the flowering period. The accumulating amount of each nutrient element is higher in the first utilization at squaring to flowering phase than that at other growing periods. It indicates that the total nutrient matter is lower when the cutting phase is earlier, and the accumulating amount of element after cutting is lower than that before cutting.