Armstrong Research and Demonstration Farm
For many years, home gardeners have recognized the benefits of applying compost and other soil amendments to their soils. Though not considered a fertilizer by industry standards, compost is universally recognized for improving structure, water-holding capacity, and the nutrient content of our soils. In many gardening systems, including both organic and conventional, compost is often the major soil enrichment product. On occasion, other soil amending products, such as humic acid, have been tried by gardeners in hopes of achieving many of the same benefits of compost, but with less volume and cost.
Iowa State University
Havlovic, Bernard J., "Evaluation of Two Soil Amendments" (2005). Iowa State Research Farm Progress Reports. 1201.