| The North Weihe Plain is the important grain crops and fruits production bases in Shaanxi Province. However, crop yield fluctuates greatly and productivity is low due to the effects of climate, soil and management. A great challenge of water shortage is faced in agriculture, especially in food production of this area. So, it becomes a very important problem to increase water use efficiency in agriculture by managing soil water more scientifically. In this paper, after a brief review of the latest developments in the field of dryland farming and soil water, the moisture data in winter wheat and spring　corn field obtained from several spots and years in Heyang County and the North Weihe Plain were used to systematically study the seasonal and vertical changes of 0～200 cm soil moisture, the feature of soil drought, water consumption law, crop water stress law, effect of crops to soil moisture, the relationship between crop yield and available water stored in soil according to the water balance. The results were as follows: (1) The lack of soil moisture primarily appeared in the middle of March to the first ten-day period of July, because of low precipitation, higher evaporation and transpiration and approximately withered soil moisture content during this period. The layer of 0～50 cm was changeable layer. (2) In years with normal climatic conditions, soil water content in the later period of winter wheat only maintains the value about 30 percent of the field capacity and, in the middle period of spring corn maintains the value higher than 50 percent. (3) The water consumption of winter wheat was 302.9～335.6mm, and soil water supply took up 34.4%～49.7% and rainfall in the plant growth period took up 50.3%～65.6% in total water consumption; The water consumption of spring corn was 298.8～427.0mm, and soil water supply took up –30.3%～27.0% and rainfall took up 73.0～130.3%. (4)The crop water stress law showed that the amount of lack of soil moisture in winter wheat was 203.0 mm and spring corn was 136.3mm. In following period of corn production, soil water content can basically meet the requirment of corn. (5)The layer of water consumption was 0～140 cm in winter wheat, which was 0～180 cm in spring corn. The amount of water consumption was 41.7 mm in 0～200 cm soil layer in spring corn and its consumption capability was 9.8%. There was percentage of 38.0～54.6% of available water in the soil after harvesting. (6) The correlated analysis shows that the water storage of soil in the layer of 0～200cm is closely correlated to the yield of winter wheat. According to this fact, we established following forecasting model: y=-0.00172x2+1.882x-207.0, r=0.9678. This article studied the dryland farming measures which are suitable to the existing water deficiency condition in North Weihe Plain. It suggests that a generl plan concerning decreasing evaporation by stubble mulching on the field first as a background in schemeing out method to enhance water utility efficiency. We also researched the effect of planting system adjustment, water collected cultivation and corn with plastic film. The results of stubble mulching indicated that when winter wheat was covered with wheat straw during summer fallow, or spring corn was covered during winter fallow, and so were their seedlings during their growth period, soil water contents increased remarkable and, also the upper layer of soil in particular kept wet for a long time. Meanwhile stubble mulching can improve soil fertility. Through a series of the agricultural technology of less till, stubble mulching, variety utilization and chemical herbicides was employed, the moisture and soil retention efficiencies were increased and crop yields enhanced. According to experiments, the plowing operation frequency decreased from 7～8 times to only once or no-tillage. The wheat yield upgraded from 3.562 t/hm2 to 6.105 t/hm2 and, the corn yield upgraded from 5.544 t/hm2 to 9.570 t/hm2. Effects of stubble mulching on crop land soil moisture content and spring corn growth showed that the soil moisture content in the soil profiles that covered stubble differ from the soil moisture content in bare profiles. Compared with the former, the soil moisture content has no obvious horizon variety in bare profiles but it is greatly influenced by the precipitation and evaporation. The variable range of soil moisture content distribution is obviously because the situation of stubble cover and soil physical features are different. Compared with the Check, the covered stubble has higher soil moisture content, the maximum is 18% in the soil layer of 0～40cm in jointing stage. In seedling stage, corn root was mainly in 0～30 cm and the root length was very small. Root length increased dramatically in booting stage and filling stage and root mostly distributed in 0～60 cm and 0～90 cm soil layer, respectively. The covered stubble could increase water utilization and the capability of stored water and it could prompt the root growth of spring corn obviously and raise the per unit yield of 32.1%. The film mulching and interplanting cultivation test showed that it could increase water stored, increase the percentage of rainfall usage, prompt the goal of high yield. The test on the wheat cultural technology of high-yield indicated that the effect sequence of three factors on wheat yield was planting way>fertilizer>sowing norm. The cultural technics of maximum yield at more than 400 kg·667m-2: Sowing norm was 8 kg·667m-2, nitrogen fertilizer dose was 12.6 kg·667m-2, phosphate fertilizer dose was 8.6 kg·667m-2, planting way was covering film in winter wheat. The paper has analysed the dryland farming water-saving technology, such as crop planting system of increase of autumn crops, horizontal ditch cultivation and big furrow cultivation, drought-resistance cultivar, etc., popularized in production in Shaanxi province in recent years, which enable to improve the integrated production capacity of dryland farming greatly.
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