Agro-climatic zonation of Khouzestan province based on potential yield of irrigated wheat using WOFOST model

By application of climatic zoning methods, it is possible to study different agricultural aspects and then with harmony this aspects, determined similar states in a zone. Today, simulation models are widely used around the world in agricultural research and education and cropland management. Due to the vast extent of the agricultural activities in Iran, application of such models seems to be quite necessary for optimization objectives. The primary focus of this research was climatic zoning of Khouzestan region based on the results from wheat yield potential by means of WOFOST model. First, model performance and the accuracy of its results were evaluated. The findings showed that WOFOST model can adequately simulate phenological phases and grain and dry matter yields. The calculated Root Mean Square Error (RMSE) values from blooming and physiologic maturity of crop were 1.97 per day and for seed and dry matter performances 810 and 810 kg ha-1, respectively. Also, one-to-one linear regression values for these stages were 0.96, 0.97, 0.93 and 0.91, respectively. The results of simulations indicated that the potentials of crop yield and the actual yield of farmlands are considerably different. Determination of the yield potentials of crop and its restricting factors were considered as the first step toward higher yield of crop. The results emphasized the fact that maximum and minimum yield potentials were found near the cities of Izeh (9247 kg. ha-1) and Shushtar (7538 kg. ha-1). A comparison of potential and actual crop yield trends revealed that the latter has been decreased might be due to the global warming phenomena resulting from green gases release into atmosphere while the increase of the farmer has been related to genetic modification of crop and management strategic. The results also showed that the poor yield of Mahshahr croplands (65.8%) was because of unsuitable soil and high level ground water resources. The lowest performance was found in Dezful cropland (41.6%), which was mainly due to the unfavorable soil, extremely low range temperature variations and solar radiations along with suitable social-economic status of local farmers. The difference of performances at various points within Khouzestan region in terms of climate yield potentials was estimated as 18%. However, results indicated that the yield potentials and actual yields of farmers are substantially different. Still, the interpretations of results hopefully indicate that the potentials for augmentation of actual wheat performance through improvement of farming management practices and soil modification are huge.