Yield Gap Analysis: Quantifying the Determinants of Wheat Yield in the Eastern Region of Lorestan Province

Background and Objective: Quantitative assessment of the yield gap and identification of its determinants is a fundamental step toward achieving self‑sufficiency, enhancing food security and optimizing the management of biological and agricultural risks in any region. Accordingly, the present study was conducted with the aim of quantifying the yield gap and its influencing factors in two districts of Azna County, Lorestan Province.
Materials and Methods: For this research, data were collected from a survey of 85 irrigated wheat farms in Azna County using face‑to‑face questionnaire interviews. The information gathered included farm characteristics and management practices (planting, growing, and harvesting operations). Furthermore, soil and topographic data of the farms were extracted from GIS‑based layers according to the geographical position of each field. The collected data were then analyzed separately for the Central District (45 farms) and Chaplagh District (40 farms) using the Comparative Performance Analysis (CPA) method in SAS 9.3 software; Yield (output) models were prepared, and finally, the yield gap, its determining factors, and the contribution of each factor were identified for both districts.
Results: The results showed that the estimated maximum yield in the Central and Chapleq districts was 11369.30 and 8884.43 kg.ha-1 respectively, and the yield gap was 5363.33 (17.47%) and 2932.90 (33.01%) kg.ha-1. In the Central part, available soil potassium (11.61%), potato pre-crop (27.15%), base phosphorus fertilizer consumption (23.36%), number of irrigation times (28.33%), and harvest time (9.55%) were the main factors affecting the yield gap. In the Chapleq districts, soil nitrogen content (18.16%), carrot pre-crop (2.67%), use of cultivator in seedbed preparation (5.60%), number of irrigation times (40.10%), and total net nitrogen fertilizer amount (33.48%) played the main role in the yield gap.
Conclusion: Comparing the irrigated wheat yield gap in the two districts of Azna County showed an overall yield gap difference of 2430.42 kg.ha-1 (45.32%). Analysis of the share of determining factors on the yield gap in the two studied districts showed that all factors, except for the number of irrigation times, were different. However, the effect coefficient of irrigation frequency was also different in the two districts. Therefore, according to the results obtained from this research, the yield gap can be minimized in both districts by improving irrigation system efficiency, developing irrigation schedules based on plant phenological stages, considering preceding crops, and implementing optimal crop rotation systems. Furthermore, supply of basal potassium and phosphorus fertilizers in the Central district, and the split application of nitrogen fertilizer in accordance with wheat growth stages in the Japlaq district are recommended.
of Azna County showed an overall yield gap difference of 2430.42 kg.ha-1 (45.32%). Analysis of the share of determining factors on the yield gap in the two studied districts showed that all factors, except for the number of irrigation times, were different. However, the effect coefficient of irrigation frequency was also different in the two districts. Therefore, according to the results obtained from this research, the yield gap can be minimized in both districts by improving irrigation system efficiency, developing irrigation schedules based on plant phenological stages, considering preceding crops, and implementing optimal crop rotation systems. Furthermore, supply of basal potassium and phosphorus fertilizers in the Central district, and the split application of nitrogen fertilizer in accordance with wheat growth stages in the Japlaq district are recommended.