On-farm Cyanobacterial Bio-fertilizer Production to Reduce the Carbon Footprint of Organic Fruit and Vegetable Production

View the project final report

• 2014 annual report
• 2015 annual report
• 2016 annual report

Commodities

• Fruits: peaches
• Vegetables: beets, cucurbits, greens (lettuces), sweet corn

Practices

• Crop Production: biological inoculants, fertigation, irrigation, organic fertilizers, tissue analysis
• Education and Training: demonstration, display, extension, farmer to farmer, on-farm/ranch research, participatory research
• Energy: solar energy
• Farm Business Management: budgets/cost and returns
• Natural Resources/Environment: carbon sequestration
• Production Systems: organic agriculture
• Soil Management: organic matter, soil analysis

Nitrogen (N) is the limiting factor for agricultural yields in most cropping systems. Nitrogen gas (N2) makes up approximately 78% of the Earth’s atmosphere, but in order to be useful for most microorganisms, plants and animals, N must be in a “fixed” form such as ammonium or nitrate. Agriculture has become highly dependent on N fertilizers produced through a chemical N fixation process involving very high temperatures and pressures and, hence, requiring high fossil energy inputs. Some N-fixing bacteria are heterotrophic (e.g. Azotobacter and Azospirillum) and, thus, require a source of C for growth. In contrast, cyanobacteria are phototrophic N-fixers; they can fix nitrogen from the atmosphere and can power this process by fixing their own source of C via photosynthesis. Cyanobacterial bio-fertilizer has the potential to become a new, sustainable source of N fertilizer; a fertilizer that can be produced on-farm, supplementing or replacing chemical fertilizers while decreasing fossil fuel consumption. Organic N fertilizer options are limited and are often low in nutrient content, expensive, bulky and transported long distances. In arid and semi-arid areas, water limitations can preclude common fertility improvement methods such as leguminous cover crops/green manures. In contrast, intensive culture of cyanobacteria in covered raceways allows resource-efficient production of N fertilizer on small amounts of land. On-farm cyanobacterial bio-fertilizer production is an entirely new and innovative approach to providing crop N requirements using high-N bacterial biomass, while greatly reducing fertilizer manufacturing and transportation needs. However, for cyanobacterial bio-fertilizer production technology to be applied broadly to domestic agriculture, it must be scaled up and tested on farms, especially in the challenging environments of the semi-arid West. In this project, on-farm bio-fertilizer production and use will be tested on one university research farm and four private organic farms (two vegetable farms, two fruit orchards). Economic and environmental sustainability will be evaluated through yield impacts, cost/benefit analyses and carbon footprint comparisons. Since cyanobacterial bio-fertilizer depends heavily on farmer knowledge and management, stakeholder input will guide research and make bio-fertilizer as easy to use as possible. Broad dissemination of educational materials (video, production manual, utilization factsheet, carbon footprint decision tool) will be critical to widespread adoption. Field days, regional workshops, a webinar and a website will be used for dissemination. Success of the project will result in working, profit-enhancing on-farm bio-fertilizer systems and will lay the groundwork for further dissemination of the bio-fertilizer approach. Cyanobacterial bio-fertilizer will eventually improve the profitability and sustainability of farms throughout the West and, eventually, the entire United States.

1)   Optimize the yield and efficiency of an on-farm bio-fertilizer production system
Task 1.1 – Determine if CO₂ bubbling will enhance growth and N-fixation of cyanobacteria grown in outdoor raceways.
Task 1.2 – Evaluate batch vs. semi-continuous growth of cyanobacteria.
Task 1.3 – Explore methods to optimize light absorption.

 2) Evaluate the utilization of cyanobacterial bio-fertilizer in irrigated fruit (apples, peaches) and vegetable (lettuce, sweet corn) systems

 Task 2.1—Compare cyanobacterial bio-fertilizer with commonly-used organic fertilizers (compost, fish emulsion, feather meal and blood meal) in terms of impact on plant growth, yield, quality and N recovery.

 Task 2.2—Assess the effectiveness of cyanobacterial bio-fertilizer in contrast to farmers’ current practice on two working vegetable farms and two orchards.

 Task 2.3 -- Evaluate the barriers to integration of cyanobacterial bio-fertilizer into current organic farming systems.

3) Quantify the direct costs and benefits of on-farm production and utilization of bio-fertilizer to optimize economic returns for farmers

 Task 3.1—Quantify the costs of cyanobacterial bio-fertilizer production as compared to commonly-used organic fertilizers.

Task 3.2—Appraise the economic benefits of cyanobacterial bio-fertilizer use.

Task 3.3 --Evaluate the economic feasibility of on-farm production and use of cyanobacterial bio-fertilizer.

4) Determine the carbon footprint of bio-fertilizer compared to other methods of fertilization

Task 4.1—Monitor the N₂O and CO₂ emissions from cyanobacterial bio-fertilizer applied to land as compared to commonly-used organic fertilizers (compost, fish emulsion, feather meal and blood meal).

Task 4.2—Modify the Daycent model to include cyanobacterial bio-fertilizer and other organic fertilizers for use in quantifying and comparing the carbon footprint of those fertilizers.

5) Impact farmer decision-making by sharing results through multiple methods

Task 5.1—Develop educational tools including a manual, factsheet, video, C footprint decision tool and website.

Task 5.2—Disseminate educational tools and research results locally, regionally, nationally and globally.

Task 5.3—Quanitfy and maximize producer adoption through continuous communication and feedback.