Documentation and Identification of Factors Reducing the Yield of Some Crops in Kurdistan Province by CPA Method

Increasing crop production is essential to ensure food security for the growing population. To improve yield, it is necessary to identify the yield gap in each region and determine the factors affecting this gap in crop production.
To document the production, this research was conducted as a survey in the agricultural years 1402 and 1403 in the villages of Kurdistan province. In the first year of the experiment, 110 farms and in the second year, 120 farms were randomly selected in these areas. The total cultivated area of the studied farms in the first and second years was approximately 510 and 545 hectares, respectively. All management practices of the selected farms were supervised by agricultural engineers. The planting season was considered based on the type of autumn crop. In this research, the CPA method (Comparative Performance Analysis or stepwise regression) was used for data analysis. To determine the yield model (production), the relationship between all measured variables (quantitative and qualitative; qualitative variables were coded as zero and one, and yield was examined through the stepwise regression method).
Documentation results showed that in fifty percent of wheat, barley, and canola farms, the amount of seed used varied by more than 180, 165, and 8 kg per hectare, respectively. Also, fifty percent of farmers used more than 50 kg per hectare. The average plant density in wheat, barley, and canola was 422, 340, and 54 plants per square meter, respectively. Also, the experience of farmers for cultivating wheat and barley was between 4 and 50 years, and for canola, it was between 4 and 30 years. The average area of farms for wheat was 9 hectares, for barley, 4.5 hectares, and for canola, 8.3 hectares. The Pishgam wheat variety, Bahman barley, and Neptune canola also had the highest frequency in cultivation. In the previous cultivation for wheat, barley, and canola, fallow, cereals, and cereals had the highest frequency of presence, respectively. For seedbed preparation, the use of moldboard plow in wheat and barley and goosefoot cultivator in canola had the highest usage. Based on the CPA results in wheat cultivation, the contribution of yield-limiting factors was: 1) seed rate (kg/ha): 39.7%, 2) urea fertilizer application after planting: 30.1%, 3) plant density (plants/m²): 13.9%, and 4) phosphorus fertilizer application (kg/ha): 16.3%. In barley cultivation, the contribution of yield-limiting factors was: 1) seed rate (kg/ha): 42.8%, 2) urea fertilizer application after planting: 20.6%, and 3) plant density (plants/m²): 36.4%. In canola cultivation, the contribution of yield-limiting factors was: 1) farmer experience (years): 34.4%, 2) urea fertilizer application after planting (kg/ha): 18.0%, 3) plant density (plants/m²): 14.5%, and 4) phosphorus fertilizer application (kg/ha): 33.5%.
The results generally indicate that by optimizing the management of key agricultural factors such as the application of urea and phosphorus fertilizers, seed rate, and plant density, while paying attention to the skills of farmers in all agricultural operations of crops, there is significant potential for improving crop yield in the studied area. In general, the CPA method provides a systematic approach to evaluating yield potential and identifying the main yield-limiting factors in the studied area, which can provide targeted interventions to reduce the yield gap. The results generally indicate that by optimizing the management of key agricultural factors such as fertilizer application, seed rate, and plant density, there is significant potential for improving crop yield in the studied area. Addressing these management limitations can help reduce the yield gap and increase the productivity of cropping systems.