The maintenance of optimum mineral nutrient fertility is a limiting factor in organic vegetable systems, with many growers resorting to applications of off-farm commercial fertilizer inputs. In this study, pelleted sheep’s wool was compared against a standard commercial fertilizer product for effects on productivity and plant growth in spinach and tomato. Two rates of wool pellets were applied; one was standardized to the nitrogen inputs of the ‘grower standard’ commercial treatment, and a second higher rate which was suggested by the pellet manufacturer with about 2.5 times the nitrogen content. Overall, few differences were observed among the fertilized treatments. Crop yield for both tomato and spinach generally increased with increasing fertility application, with no differences between commercial and wool pellet fertilizers applied at the same rate of nitrogen. The uptake of mineral nutrients in spinach plant tissues differed for K, Mg, P, S, B, and Ca, but there was no general trend that could be attributed to a particular treatment. Tomato fruit quality was the same for all treatments, but non-fertilized fruit had lower total polyphenols than the highest-fertility treatment. Overall, wool pellets performed very similarly to commercial organic fertilizer for both crops and could be a promising alternative that may open up opportunities for greater integration of plant and animal systems on diversified farms.
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