| The study was primarily conducted to investigate the effects of various irrigation managements on the yield, quality and WUE of alfalfa and the sustainable utilization of soil-water in North China plain.Five treatments were applied: 0mm, 30mm, 50mm, 75mm and 100mm irrigating at the beginning of the second growth cycle in 2001. We found that the higher midlayer and deeplayer water contents after harvest, the faster alfalfa grew, and, the more quickly covered the bare soil, the more soil evaporation restrained. In this way, the soil could sustain higher shallow soil water contents. In the arid season, the output of soil water distinguishly outweights the input. On the contrary, the input had subtle surplus in rain season. It could be concluded that the relationship between the growth rate about ground biomass in the same growth period and soil moisture content was a logarithmically function. The efficiency of irrigation in the beginning of the growth cycle in arid season distinctly surpassed the average WUE.Twelve treatments of combining different times and amounts of irrigation were applied in 2002. The alfalfa gross yield logarithmically correlated the amounts of irrigation in North China plain. The times before the EP(initial-period), that before the FGP(fast-grow-period) in harvest I , and that before the FGP(fast-grow-period) in harvest II were the best ones for irrigation. Various treatments couldn't result in the difference in the nutrient components of alfalfa in the same variety. Irrigated before FGP in harvest II, it could provide more high quality alfalfa in front of rain season. WUE could be enhanced through insuring the produce of the harvest I and II or refraining soil-water from evaporating. The rainfed field could provide a content yield, if the soil moisture condition of the first harvest I's IP is good. It was difficult to meet output with income of the alfalfa soil-water in North China plain regardless irrigated or not, this might result in the drought in deep soil. |
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