Abstract: The purpose of this experiment is  to screen out the optimal match ratio of the recycling amount of Chinese milk vetch (Astragalus sinicus L.) and the application level of nitrogen fertilizer and thus to provide theoretical basis for improving rice production. This experiment adopted a split plot design with no application of Chinese milk vetch or nitrogen as control one (CK1), the conventional nitrogen application level (180 kg·hm^-2) as control two (CK2). The application of Chinese milk vetch included two levels: 27000 and 45000 kg·hm^-2 (designated M1 and M2 respectively), and the application of nitrogen fertilizer included four levels: 0, 60, 120 and 180 kg·hm^-2 (designated N0, N1, N2, N3 respectively). The effects of coupling different amounts of Chinese milk vetch and nitrogen on rice yield, dry matter accumulation and nitrogen useefficiency of rice were examined. The results showed that the applications of 27000 kg·hm^-2 of Chinese milk vetch + N ≥120 kg·hm^-2 and 45000 kg·hm^-2 of Chinese milk vetch + N ≥60 kg·hm^-2 could ensure the rice yield and growth. M1N2 had the highest yield, being 11.56% higher than CK2. In the ripening stage of rice, dry matter accumulation of M2N1 was thehighest, being 21.41% higher than CK2; nitrogen absorption amount of M2N3 was maximum, being 5.32% higher than CK2. The apparent and real utilization of nitrogen fertilizer decreased with the increases of nitrogen application level. The treatments of M1N2 and M2N1 can ensure the rice yield and  improve the utilization rate of nitrogen fertilizer, which would be beneficial to the efficientutilization of resources.

Key words: ecosystem, value eva-luation, service value, eastern foot of Helan Mountain, grape industry