Abstract: The suitable ecological conditions are greatly advantageous for cotton production in Hebei Low Plain. Precipitation is one of important factors effective on cotton growth.Generally,lint yields are higher in drought years than in humid years. Different management measures should be taken in different rainfall years. The key to high and stable yields is to establish a proper population structure and to maintain fine eco-environment in cotton fields.

Key words: alfalfa, soil organic carbon functional groups, stability, hilly south region of Ningxia.