The Effect of Soil Moisture and Climatic Index of Evapotranspiration on Forage Production in Rangelands of Dehsir, Yazd province, Iran

Estimation of long-term pasture production using important factors of climate and soil characteristics on forage production is inevitable. Reduced water and precipitation is important factor limiting production of fodder, especially in arid and semi-arid areas. Water use efficiency in these areas is the amount of water stored in the root orientation early in the growing season and water spread area of effective rainfall in the growing season that is used for evaporation and transpiration in plants. One of the important sections of the hydrological cycle is evapotranspiration. The transpiration directly affects forage production. The basis of estimating the water requirement of plants is the potential evapotranspiration which can be calculated by different methods. In this study, forage production in steppe rangelands of Dehsir, Yazd province, Iran were estimated using climatic index of potential and actual evapotranspiration and soil characteristics using Penman-Montith (Cropwat 8.0 software). The climatic data were provided from Dehshir Rainfall and Abarkooh Synoptic Station. Soil samples were taken by Auger at the beginning period of the growing season and soil moisture content was obtained weighing the soil before and after drying to constant weight in oven (100°C) in 2013. Then the regression model for estimation of forage production using soil moisture and evapotranspiration as independent variables was developed. The results showed that forage production had a strong correlation with the climatic index of actual evapotranspiration according to the estimation of actual evapotranspiration in a ten-year period, a model was provided for forage production as Ya=194.85+1.132(ETact). It could be said that actual evapotranspiration as an index for climate yield is one of the fundamental factors in estimating forage production.