A study investigating organic nutrient management conducted at Colorado State University found that on-farm–grown cyanobacterial fertilizer, or cyano-fertilizer, can match or even outperform traditional organic fertilizers like fish emulsion when it comes to crop yield and quality. The results highlight a promising opportunity for organic farmers, who can lessen their reliance, and the associated costs of external fertilizers by producing nitrogen inputs directly on farm.

The field experiment took place at Colorado State University’s certified-organic Horticultural Research Center in Fort Collins, Colorado. Using a randomized experimental design to test soil and foliar fertilizer combinations, the researchers compared the effects of cyano-fertilizer with hydrolyzed and non-hydrolyzed liquid fish fertilizers on organic carrot yield, quality, and soil nitrogen levels. The cyano-fertilizer, produced on-site from nitrogen-fixing Anabaena species, was applied through drip irrigation and compared against two types of fish-based fertilizers. Researchers also included foliar seaweed applications to test the potential effects of phytohormones, natural plant growth regulators present in seaweed and some fertilizers but found they had little impact on yield. Over two growing seasons, carrots treated with cyano-fertilizer yielded equal to or greater than those grown with commercial fish fertilizers, even when lower nitrogen levels were applied. The cyano-fertilizer also produced longer roots and similar rates of deformities, such as knobs or underdeveloped carrots, suggesting it can effectively supply mid-season nitrogen without compromising crop quality.

These results demonstrate that cyano-fertilizers can be a viable and sustainable alternative to traditional organic nitrogen sources. Producing fertilizer directly on farm can reduce input costs and help farmers move closer to a closed loop system. In the search for practices to improve crop outcomes and soil health, applying biologically appropriate fertilizers like cyano-fertilizers presents a promising path for organic producers.