حمید مطوریان

Food security is one of the most important challenges facing humankind. Therefore improving crop yields are essential to meet the increasing pressure of global food demands. The Decreasing the area of high-quality land, increasing fertilizer use, and its effect on the environment indicate that we need to develop new strategies to increase grain yields with less impact on the environment. One strategy that could help address this concern is by narrowing the yield gaps using improved management. Therefore, the present study was conducted in Khorramshahr region for recognition of best management practices, percentage of the affected fields, estimation of wheat and rapeseed yield potential and gaps using boundary line analysis.

To quantify the production and estimation of wheat and rapeseed yield gap in Khoramshahr, Farm management information of 60 wheat fields and 57 rapeseed fields in the years 2018-2019 were collected. The information was collected through continuous farm monitoring during the growing season as along with face to face interviews with the farmers. Farms were selected by consulting with agricultural service centers expert in Khorramshahr districts. Based on the available information at the agricultural service centers, only farms, which is different in terms of acreage, cultural practices and harvesting operations were selected. In this study, by plotting the distribution of the yield obtained in each field as the dependent variable against the independent variables (crop management activities), using SAS software and an appropriate function was fitted on the upper edge of the data distribution.

Using this boundary line analysis method, the average yield, attainable yield and yield gap of wheat were obtained as 3740, 5455 and 1715 kg per hectare respectively. The yield gap percentage in wheat was 31.5% and rapeseed was 48%, which indicates the high effectiveness of wheat and rapeseed in relation to the use of appropriate management methods. The analysis of the investigated data in wheat fields showed that in order to achieve the achievable yield, 258 kg per hectare of seeds, the use of Mehrgan variety, the planting date until October 24, the amount of 280 kg per hectare of nitrogen fertilizer, the consumption of at least 100 Phosphorus fertilizer per hectare was at least 6 kg with irrigation and consumption of at least 70 kg of potassium fertilizer. Also, according to the frontier line analysis, the average yield of rapeseed farmers is 1663 kg, they can achieve a yield of 3197 kg per hectare by improving crop management, and for this purpose, the following measures should be taken into account: 1) consuming a maximum of seven kilograms of seeds per hectare 2) Planting date up to 17 November 3) Use of at least 300 kg of nitrogen fertilizer 4) At least 42 kg of phosphorus fertilizer 5) Use of Hyola 50 variety.

In this study by examining several important management factors in growing wheat and rapeseed, optimal requirements of each factor to achieve the highest yield was determined by borderline analysis. In addition, the percentage of farms that had poor management as well as wheat and rapeseed yield potential and gaps in Khorramshahr. Yield responses to management practices were evaluated and studied by means of borderline analysis. Best management practices could be devised using study findings to realize the highest yield potential.

Food security is one of the most important challenges facing humankind. Therefore improving crop yields are essential to meet the increasing pressure of global food demands. The loss of high-quality lands, increasing fertilizer use, and its effect on the environment indicate that we need to develop new strategies to increase grain yields with less impact on the environment. One strategy that could help address this concern is by narrowing the yield gaps using improved management. Comparative Performance Analysis (CPA) is an approach for studying yield gaps; it defines quantified yield-gap functions. Assessing the yield gaps in major field crops can help us understand yield variability and potential. Rapeseed is one of the world’s most important oilseeds, and its production has economic and agronomic advantages. Rapeseed oil is considered a healthy ingredient and the third most used oil in foods. There is a difference between the average yield and the maximum expected yield of rapeseed in Khorramshahr. There are potential lands in this region that, by investigating the reasons for low yield, farmers can be encouraged to cultivate rapeseed on their farms. Therefore, this study aimed to determine the yield gap and the limiting management factors in rapeseed cultivation of Khorramshahr.

This study was carried out to investigate management factors causing the rapeseed yield gap in Khorramshahr during the 2018-2019 growing season. This study recorded information from 57 farms with variation in the area under cultivation, farm management and yield based on information from local experts and field studies. The comparative performance analysis (CPA) method was used to evaluate the yield gap. All information related to management practices was either measured or recorded. From the relationship between all measured variables (quantitative and qualitative) yield model was obtained through stepwise regression. By putting the best-observed value of the variables in the model, the maximum attainable yield was calculated, and the difference between them was considered a yield gap.

The yield observed in the surveyed farms, and the yield predicted by the model show a significant relationship. In this regard, the correlation coefficient was 93%, which indicates the high accuracy of the model for predicting the yield gap of the studied rapeseed fields. Based on the model, nine independent variables were selected from all studied variables. Then actual and attainable yield and contribution of each variable to the yield gap were determined by using the model. Results showed that the average yield, achievable yield, and yield gap of rapeseed were 1663, 3197, and 1533 kg.ha-1, respectively. The most important variables in the rapeseed yield gap were the use of the leveler, farmer’s education level, phosphate fertilizer application, time and amount of potassium fertilizer application and method of removing crop residues of the previous year, irrigation frequency, and sowing machinery. Factors that had the highest share of yield gap were potassium application time (27.14%), application of superphosphate (26.85%), potassium rate (25. 9%), crop residues removing method (9.63%), and use of lever (9.13%). According to the findings, the highest contribution to the yield gap was related to potassium fertilizer application time and superphosphate fertilizer application. These variables caused a yield gap of 416 and 411 kg.ha-1, respectively.ConclusionThis study showed a difference between the actual yield and potential yield of rapeseed fields in Khorramshahr, which can be reduced by modifying crop management. The observed yield gap was 1533 kg.ha-1 (48%). The results of this study indicate that fertilizer management of Khorramshahr rapeseed fields, especially potassium and phosphorus fertilizers, is important and should be considered by farmers in the region. More than half of the rapeseed yield gap can be reduced by using phosphorus fertilizer and changing the time and rate of potassium application in Khorramshahr.

The study was conducted to evaluate the energy use efficiency, greenhouse gas emission and evaluation of sustainability in the studied wheat and rapeseed fields of Khorramshahr. Input data and yield of fields were collected from 60 wheat and 57 rapeseed farms of Khorramshahr by using questionnaire method and face-to-face interview during 2018-2019 growing season. Results showed that input energy of wheat and rapeseed was 41810 and 33517 MJ ha-1. Electricity, nitrogen fertilizer and fuel had the greatest impact. Direct energy was 22606 and 19434 MJ ha-1 and indirect energy was 19204 and 14083 MJ ha-1 for wheat and rapeseed respectively. Also, the input energy of renewable wheat and rapeseed was 5546 and 314 MJ ha-1, and non-renewable energy was 36263 and 33202 MJ ha-1, respectively. Energy efficiency for wheat and rapeseed was 1.32 and 2.15. Greenhouse gas emissions per hectare of wheat and rapeseed fields was 1438.5 and 1466 kg, respectively. Equivalent to carbon dioxide per hectare and the global warming potential was 18223 and 2238 tons of carbon dioxide, respectively. In this study, the sustainability index based on the amount of carbon input and output in wheat was 2.45 and in rapeseed was 1.17. Energy management is important and effective for efficient and sustainable energy use in wheat and Rapeseed agroecosystems of Khorramshahr. Optimizing energy consumption and reducing energy costs is essential to maintain sustainable environment.

One way to increase crop yield per unit of area is to close the gap between actual and potential yield in cropping systems. This study was conducted to determine the factors that affeced wheat yield gap in Khorramshahr, Iran during 2018-2019 growing season. In this study 60 fields of different areas under cultivation, field management practices and grain yield yield levels were surveyed based on information from agricultural services centers and continuous monitoring. Comparative performance analysis (CPA) method was used to evaluate the grain yield gap. Theaverage grain yield, attainable grain yield and wheat yield gap in Khorramshahr were 3740, 5455 and 1715 kg.ha-1, respectively. Estimated yield gap (31.5%) in this study indicated that the high importance of appropriate management practices on wheat grain yield. Most important variables affected wheat grain yield gap were included Illoxane herbicide application (579 kg.ha-1), farmers education level (292 kg.ha-1), irrigation intervals (279 kg.ha-1), potassium fertilizer application rate (256 kg.ha-1) and planting machinery and equipment (179 kg.ha-1). These factors accounted for 87.45% of the calculated grain yield gap. The results of this study showed that by improving crop management practices, the grain yield gap of wheat fields in Khorramshahr region can be reduced.