Study On The Utilization And Consumption Of Water For Sward In Semiarid Agro-pastoral Transitional Zone Of North China

The study in Heibei province in 2006 is conducted to probe into the interaction of different irrigation treatment on the growth of two kind of pastures (Medicago sativa L. and Bromus inermis L.) which were sowed in 2002, WUE(Water Use Efficiency) and the sustainable utilization of soil-water. The results show that:1. Different irrigation treatment brought different effects on the morphological characteristics of Bromus inermis L., of which the plant height, stem numbers, leaf area and underground biomass were affected the most. The treatment with more water was in favor of increasing the plant height and leaf area, and the treatment with less water was in favor of increasing the stem numbers and the growth of underground biomass. In 2006, the order of aboveground biomass under different irrigation treatment was W2>W4>W3>W1, but the effects on the aboveground biomass were not significant. In 2006, the dry weight of aboveground biomass of W2 was the largest, 1988.2 kg/hm² ? and the WUE of W2 the most efficient, 0.73 kg/m³.2. Different treatment brought different effects on the morphological characteristics of Medicago sativa L. The treatment with more water was in favor of increasing the plant height, stem numbers and leaf area. The stem numbers of W3 and W4 which were treated with abundant water were larger than that of W1 and W2 which were treated with less water during the whole growth reason. The aboveground biomass of W3 were also in larger quantity. In harvest I the dry weight of the aboveground biomass of W3 was 1104.1 kg/hm² and in harvest II 649.7 kg/hm². The WUE of W3 was higher . In harvest I the WUE of W3 was0.519 kg/m³ and in harvest II 0.349 kg/m³.3. The general condition of soil water of the Bromus inermi L. artificial grassland in 2006 is as follows. Water content in each soil layer was low in the initial period of the plant growth in the dry season. The first irrigation in June greatly influenced the water content of the upper soil layer while brought little effect on the water content of the lower soil layer. The second irrigation in July increased the water content of all soil layers (including W1 which was not irrigated). In the later period of Bromus inermi L. growing season in August, the water content of all soil layers decreased in W1 which was not irrigated in the whole growing season, and that of other treatments was also decreasing but not much different from that of July. Moreover, the water content of the lower soil layer of the three irrigated ones was increasing. During the whole growing season of the plant from May to August, there was no deficit in all the soil water content treated with different irrigation.4. In the dry season of 2006, the water content of Medicago sativa L artificial pasture was low. After the rainy season, the water content of the upper layer was increased as irrigation was conducted while that of the middle and deeper layers was increased slower. In June, the water content of every layer of the three irrigated patches was generally increased, but was no much different from that of May. In the rainy season of June, except the water content of the deeper layer of W1, the water content of W1, W2, W3, W4 was increased than that of June. In August, the water content of the upper layer was decreased than that of June and that of the layers below 50cm was increased. The water content of W2 was decreased. As to W3, only the water content of the layer of 0-10cm and 20-30cm was obviously higher that that of June and that of the other layers was no different. As to W4, the water content of the layers above 70cn was increased and that of the other layers was decreased. The last survey of Sep. 20^th on the water content in the Medicago sativa L growth season showed that the water content of every layer of W1, W2, W3, W4 was lower than that of August. In the whole plant growth season from May to September, the water content of all treated patches was balanced except W1.