New approach for regional crop yield gap analysis in the Borujen Plain, Iran

Abstract

This study was performed to analyze the regional crop yield gap for potential and water-limited production situations in the cold-semiarid climate at Borujen basin, Iran. Experimental data were used for model calibration and evaluation of WOFOST as a crop growth simulation model. WOFOST divides wheat growth into three key development stages: 1) emergence, 2) flowering and 3) physiological maturity. The length of growth period and phenology was calibrated using the field experiments results. In general, simulated results matched well with the measured parameters in the calibration procedure. Calibrated results of WOFOST model are linked to a geographic information system, in order, to get easier their presentation and also to contribute to identification of hotspots for interventions aimed at yield improvements. Finally, the results of quantitative analysis (yield estimation in different wheat cropping systems) performed on four different agro-ecological zones, include: 1) yield gaps = 4.2 to 6.2 Mg/ha, 2) yield gaps = 3 to 3.6 Mg/ha, 3) yield gaps < 2.4 Mg/ha, and 4) is unsuitable area. This yield gap between potential and rainfed production system is due to rainfall period during spring when temperature is not a limiting factor for wheat growth. Borujen Basin has semiarid climatic conditions with cold winter and winter precipitation. For the sake of it, temperature was a decisive factor during rainfall seasons, limiting the crop growth period. This study demonstrates that WOFOST model can be used to analyze cropping systems and accurately simulate regional wheat yields in cold semi arid climates.

Key words: GIS, yield gaps, wheat, suitability, WOFOST.