关键词: CO2浓度, CO2浓度, 碳水化合物, 产量, 水稻

Abstract:

ABSTRACT Sown pasture is an important part of ecological construction and agricultural production in semiarid loess hilly-gully region. It is also important for selecting proper sown pasture types and management methods after comparing the biomass production, soil water contents of different sown pastures. The yearly change of the biomass production, soil water and nutrient content were compared between lowland and slopland at Ansai loess hilly-gully region. Soil water characteristics of sown pastures: The change of soil water content in 0-100cm soil depth of lowland sown pasture was more active, and which was the active layer; soil water content in 100-350cm soil depth was related with the root system consumption, and was hypo-active layer; the seasonal change of soil water content in 350-500cm was small, and which was relatively stable layer. The soil drying phenomenon was distinctive in 350-500cm soil layer of switchgrass and alfalfa. In 2004-2005, the soil water storage in 0-200cm decreased from Aril to September, while increased from September to November. There were great differences among pastures in soil depth below 200cm, but the seasonal change was similar. The 0-100cm soil water content in late autumn was higher than in springtime at slope pasturelands, and there were no evident soil water stress in 100-500cm in each pastureland.