The Effects of Different Soil Amendments on Fertility and Productivity in Organic Farming Systems

Productivity and soil fertility are two of the most important factors in farming.Many organic farmers fertilize their crops with composted plant or animal waste.Some organic farmers who do not have access to large amounts of compost utilize processed fertilizers that are acceptable under certified organic standards.I hypothesized that soils fertilized with composted organic matter would be more fertile and productive than soils fertilized with processed organic fertilizer.To test the hypotheses, I measured nutrient content and availability at three organic farms, each of which uses a different type of fertilizer (animal manure, composted mushroom growing medium, and processed fertilizer).I also grew beans (Phaseolus vulgaris) in soil from each of the farms to measure bean weight as an estimate of productivity.The soil amended with animal manure was the only treatment that resulted in increases in nutrients, nutrient holding capacity, and bean weight.Soils amended with processed fertilizer showed little difference from controls.