Extended Abstract
1.      Introduction: One of the most multipurpose cropping is the use of mechanization and agricultural machinery is during the harvesting period. Therefore, the plants that are harvested currently by hand in sole cropping systems can get rid of this limitation successfully. In this connection, the cultivation of both sweet corn and kidney beans can be a suitable option for introducing it in multiple cropping systems. Additionaly sweet corn intercropped with beans can be advantageous due to the additional price, direct market, and hand harvesting. This agricultural system is also efficient ecologically because of the structural differences, low interspecific competition, and improved use of environmental factors such as light, water, and soil nitrogen content. In addition, the issue of using chemical fertilizers is very important, especially in vegetables that are used directly and fresh, such as sweet corn. In this regard, Intercropping can use resources efficiently compared to pure cropping, at the same time as increasing the total yield per unit area and increasing the efficiency of nutrient consumption. Mixed cropping is also considered a method to reduce losses of high-use elements, especially nitrogen.
2.      Materials and Methods: In order to investigate the nitrogen effect on the sweet corn intercropped with kidney bean, an experiment was conducted in the 2017-2018 growing season as split plots designe based on a randomized complete block design in three replications. The main plots were the management of nitrogen consumption from the source of urea fertilizer (80, 160, 240 kg/ha and controls) and the intercropping pattern (one row of corn, one row of kidney bean, one row of corn, two rows of kidney bean, two rows of corn, one row of kidney bean, kidney bean and sweet corn purecropping) formed as sub-plots. Each subplot consisted of six rows of three meters long and 50 cm row spacing for both sweet corn and kidney bean, with the four middle rows considered for sampling. One square meter from the middle of each plot was harvested at 70-75% humidity in order to determine the yield and yield components of sweet corn. Some intercropping indicators were used to evaluate mixed cultivation compared to pure cultivation, including Land Equivalent Ratio (LER), Relative Value Total (RVT), Productivity Index (PI), and Competition Index (CI).
3.      Results and Discussion: The results showed that nitrogen consumption and intercropping affect the number of seed rows, cob length, cob diameter, stem diameter, cannable seed weight, total fresh weight, dry weight of seeds, and biological yield. Also, the number of seeds per row, cob length, cannable grain weight, grain dry weight, and biological yield were significantly affected by the interaction of nitrogen and planting arrangement. The treatment combination of 240 kg/ha of nitrogen fertilizer along with the cultivation pattern of two rows of corn and one row of beans was better than other treatment combinations based on the measured traits. Also, the pattern of planting two rows of sweet corn and one row of beans showed its superiority in terms of cob length (32.64 cm) and the number of seeds per cob (35.75). The highest RVT value total was related to the control and cultivation of two rows of sweet corn and one row of kidney beans, with the consumption of 80 kg/ha of nitrogen fertilizer (0.86 and 0.85, respectively). The CI was also positive in the control treatment and the cultivation of one row of sweet corn and two rows of kidney beans, which indicates the dominance of sweet corn in mixed cropping. Ultimately, the combination treatment of 80 and 160 kg/ha and the intercrop pattern of one row of sweet corn and two rows of beans had the highest index of land equality ratio (1.16).
4.      Conclusion: Mixed cultivation of one row of sweet corn and two rows of red beans had the highest index of land equality ratio. Also, the estimation of the competition index in most of the intercropping treatments showed that sweet corn was the dominant species and used the environmental conditions more favorably. However, due to the lack of a significant difference between the yield obtained in the treatments of 160 and 240 kilograms of nitrogen per hectare, it is possible to save on fertilizer consumption and costs by using 160. Finally, according to the performance and economic indicators, the combinations of two rows of sweet corn with one row of red beans or one row of sweet corn and two rows of red beans, with consumption of 160 and 240 kg per hectare, can be introduced as the best treatments in this research.