Potential of Managing Iron and Zinc Deficiency in Dry Beans with Interplantings of Annual Ryegrass and Increased Bean Density

View the project final report

• 2008 annual report
• 2009 annual report

Commodities

• Agronomic: millet, rye, wheat
• Vegetables: beans

Practices

• Crop Production: application rate management, intercropping, multiple cropping, nutrient cycling, tissue analysis
• Education and Training: demonstration, display, extension, farmer to farmer, networking, on-farm/ranch research, participatory research
• Natural Resources/Environment: biodiversity
• Pest Management: mulches - living, mulching - vegetative
• Production Systems: agroecosystems, holistic management
• Soil Management: nutrient mineralization, organic matter, soil analysis, soil quality/health

Dry beans are extensively grown throughout the western Great Plains. Dry beans are the fourth most valuable crop in Wyoming after hay, sugarbeet and barley. Micronutrient availability can be a critical limitation on bean production and health. In Wyoming, the high pH, low organic matter and calcareous soils prevalent in the state limit the availability of many micronutrients, especially iron. Iron deficiency results in interveinal chlorosis in beans and a higher susceptibility to insect and disease damage, thereby reducing yield and quality. In contrast, zinc deficiency is the more common problem in the more acidic soils of Kenya, where dry beans are a major source of protein for most low-income communities in Kenya. In 2002, Mike and Cindy Ridenour of Goshen County, Wyoming observed that pinto beans intercropped with annual ryegrass did not exhibit iron-deficiency chlorosis and produced better than beans grown without the ryegrass intercrop (M. Ridenour, pers. comm.). In the summer of 2006, we conducted a preliminary study (Western SARE Farmer/Rancher Grant Program, FW06-021) on the Ridenour’s farm to test the hypothesis that an annual rye intercrop could increase iron availability in a pinto bean field. Soil iron and zinc availability proved significantly higher in the bean-annual rye intercrop compared to beans alone. Iron concentration in bean leaves declined in all treatments but at a lower rate in the bean-annual rye intercrop and bean-annual rye residue (beans planted on plots in which ryegrass residues had been incorporated) when compared to the control, though this difference was not significant. During the same period, we conducted a similar study on the farm of Mr. Joseph Kamuto, a peasant farmer in western Kenya, near Kitale town, in collaboration with Manor House Agricultural Center (MHAC), a local training institution promoting sustainable (Biointensive) agriculture. Soil and bean tissue samples were collected from this study and successfully shipped to the University of Wyoming (UW) for analysis. However, due to MHAC’s funding limitations, the samples have not yet been tested. Conventional control of iron and zinc deficiency in beans is achieved by multiple foliar applications of 1 per cent iron sulfate solution or 0.5-1.5 per cent zinc EDTA applied at 20-30 gallons per acre, or similar applications of the more expensive iron chelates at approximately half the rate of iron sulfate. A non-chemical cultural practice, such as this project hopes to recommend, would be a welcome alternative for organic and natural bean producers and would also provide a more sustainable and potentially more affordable solution for conventional bean growers. This project will carry out an expanded field study at the UW Sustainable Agriculture Research and Extension Centre (SAREC) in order to validate and/or corroborate our findings from the Ridenour’s study. We will also analyze the soil and tissue samples collected from Kenya in 2006 at the UW Soil Science Laboratory.

To determine the effectiveness of intercropping annual ryegrass with pinto beans in mitigating iron deficiency in calcareous soils. This will be compared to interplantings of wheat as a grass known to exude compounds capable of chelating iron.

To determine the effectiveness of intercropping annual ryegrass with pinto beans in the field in mitigating zinc deficiency in more acid soils. This will be compared to interplantings of wheat as a grass known to exude compounds capable of chelating zinc, and interplantings of millet, a hardy cereal food crop popular in western Kenya.