Water Requirement Prediction Of Artificial Pasture And Optimizing Of Its Irrigation Schedule In Northwestern China

Nowadays, under resources is becoming more deficient, irrigation water volume is insufficient, how to optimally allocate the limited irrigating water at the different growth stage of crops and how to irrigate the crop to get maximal benefit and become a lot of research in the agricultural irrigation field. For example of the Songshan sands grassland along Tianzhu, in Gansu province, made the initial research of the major water reqiurement and irrigation schedule optimizing,the results are following:(1) Analyzing the influence of soil water stress to yield, physiological status (plant height, LAI, leaf water potential and transpiration speed), Soil water potential and the change of leaf water potential and transpiration speed of Elymus dahuricus and Oats at different growth stage and different soil moisture, we find out the relationship of leaf water protential and environmental factors(temperature, net radiation, saturation deficiency and water content), and establish the quantitative relation of them.(2) The water consumption of artificial grass was calculated by water balance method, and the law of water consumption was analyzed. Water consumption peak value of Elymus dahuricus is at the stage of Stem elongation to Heading; but the Oats is Heading, its maximal dialy intensity of water consumption are 5.5mm/d and 6.7mm/d respectively. The crop water requiremnts of them were calculated by crop coefficient method and the five and four factors model of water requirement are established by analyzing the releationships of crop water requiremnts and its main meteorological factors. The hydrological year was determined by long series rainfall data and the hydrological regime was predicated by considering time series method. According to the meteorological and crop data of known hydrological year, the crop water requiremnts of Elymus dahuricus and Oats in 2009a and 2014a respectively by five factors BP model.(3) According to the experimental data, we established the quantitative relation between grass yield and moisture content of whole growth season, moisture content of growing stages. From the results of comparison, Minhas and Stewart model can disclosure the numerical relation between water and yield of Elymus dahuricus and Oats, and the irrigation schedule are optimized by Real coding based Accelerating Genetic Algorithm- Dynamic Programming: to Elymus dahuricus and Oats, when the irrigation water is less than 50mm, water requirements of stem elongation and heading stage must be satisfied respectively; when 50≤M≤200mm,water requirements of jointing and stem elongation stage must be satisfied for Elymus dahuricus, but it is jointing and heading stage for Oats; when M>200mm, range increases in yield of Oats was reducing along with water supply; when M>250mm, Elymus dahuricus followed this law.