Evaluation of Factors Influencing the Yield Gap of Sugar Beet in Northern Khuzestan Using the CPA Method

Reducing the yield gap is a critical challenge in modern agriculture. Accurate estimation of this gap can play a vital role in enhancing productivity and increasing agricultural production. This study aimed to evaluate the yield gap in sugar beet fields in Shush, Dezful, Andimeshk, and Shushtar counties and identify the key management factors affecting it. During the 2022–2023 agricultural year, data on agricultural management practices from 197 sugar beet farms in the region were collected through farmer interviews and detailed questionnaires. These data encompassed all aspects of farm management, including seedbed preparation, fertilization, weeding, pest and weed control, irrigation, and harvesting operations. Data were processed using Excel, and final analysis was performed with SAS software. Stepwise regression and the Comparative Performance Analysis (CPA) model were used to identify relationships between agronomic practices and actual crop yield. The results revealed that among 82 management variables, six independent variables—poultry manure application, potassium fertilizer application, farmer experience, total top-dress nitrogen fertilizer application, micronutrient application, and insecticide application frequency—were identified as the key factors limiting sugar beet yields in northern Khuzestan. The yield gap was estimated to be 12 t ha-1, resulting from the difference between the average actual yield (74 t ha-1) and the optimal yield (86 t ha-1). Insufficient poultry manure and potassium fertilizer application and limited farmer experience accounted for 26%, 23%, and 22% of the yield gap, respectively. Other factors, including micronutrient application, top-dress nitrogen fertilizer, and insecticide application frequency, accounted for 13%, 9%, and 7% of the gap, respectively. The efficient use of poultry manure, potassium, micronutrients, and nitrogen fertilizers, enhancing farmer experience, and improving pest management can help reduce the yield gap and increase sugar beet production. These findings emphasize the importance of these critical factors and provide recommendations for improving farm management and policymaking.