The effect of growing barley-faba bean on weed control and their yield

Mixed cultivation is part of the crop rotation program and a suitable solution for weed control, especially in low-income agricultural systems. The usefulness of intercropping compared to sole cultivation in weed control is due to the deprivation of weeds in the use of resources and higher yield usefulness. By creating diversity through intercropping, the stability of cropping systems increases. In such systems, optimal conditions are created for pest management, nutrient rotation, resource utilization, and increased yield. Therefore, the need to use ecological principles such as intercropping to increase the productivity of arable land seems necessary. After cereals, legumes are the second most important source of human food and have a special place among crops. These plants have an effective role in increasing soil fertility and reducing greenhouse gases due to their coexistence with nitrogen-fixing bacteria. They are one of the most important grain legumes in the world. In 2017, the global area under bean cultivation (Vicia faba L.) is estimated at 2.463 million hectares and its global production is estimated at 4.840 million tons. The area under cultivation and its production in Iran in 2017 has also been reported to be 217.28 thousand hectares with a production of 17.882 thousand tons. The present study aimed to compare single cultivation and incremental bean mixture in a mixed bean cultivation system (barley-bean) concerning the yield of each plant and the rate of weed suppression.
     
This research is carried out at the research farm of the Faculty of Agriculture, Islamic Azad University, Shushtar Branch, with a geographical location of 32 degrees and 3 minutes north and 48 degrees and 50 minutes east and an arid and semi-arid climate, with an average rainfall of 321.4 mm and an average temperature. The annual minimum and maximum were 9.5 and 46.3 °C, respectively. Treatments included sole and mixed cultivation of barley (Valfajr cultivar) and beans (Barakat cultivar). In sole cultivation, barley density of 400 plants per square meter and bean density of 20 plants per square meter were considered based on the recommended seed amount. Treatments included sole and mixed cultivation of barley (Valfajr cultivar) and beans (Barakat cultivar). In sole cultivation, barley density of 400 plants per square meter and bean density of 20 plants per square meter were considered based on the recommended seed amount. In mixed cultivation, barley density was fixed (400 plants per square meter) and bean density was determined as a percentage of net cultivation including (12.5, 25, 37.5, 50, and 62.5%). The research was conducted based on randomized complete blocks with four replications based on the incremental method in the mixed system in the 2009-2010 crop years.
 
The net crop yield of each plant was higher compared to its mixed crop. The highest barley yield 2496 kg/ha was observed in sole cultivation. By increasing the ratio of beans in intercropping from 12.5 to 62.5%, barley grain yield decreased from 93 to 73% compared to its sole crop. The highest yield of beans was obtained in its net cultivation with 2621 kg/ha. A comparison of cultivation mixing treatments showed that by increasing the ratio of beans in mixed cultivation from 12.5 to 62.5%, bean seed yield increased from 12 to 48%. Although the grain yield of crops in the mixture was lower compared to their net cultivation, the total productivity of the land in mixed cultivation improved as a result of the higher parity ratio of the whole land. The average values ​​of land parity ratio were obtained from 1.05 to 1.23 in different ratios of barley and bean intercropping. This means that the net cultivation of each plant requires 5 to 23% more land to produce the same yield compared to mixed cultivation, which indicates that the efficiency of land use in mixed cultivation is higher than in sole cultivation. The effect of different crop ratios on dry weight and weed density was significant compared to sole barley at the 1% probability level. The highest and lowest dry weight of weeds with 71 and 47 g/m2, respectively, were related to sole barley and the ratio of 62.5: 100 (beans: barley). However, the comparison of weed dry weight in different proportions of intercropping showed no significant difference.
 
Mixed barley and bean farming can be economically and environmentally promising in most parts of Iran, with high population density, small farms and limited income. In this study, despite the decrease in barley yield due to the increase in the ratio of the associated crop (beans) to barley, intercropping was more productive according to the results of total grain yield and land parity ratios.