Vermicompost — compost made by worms and containing a high proportion of worm castings — contains high levels of both macronutrients (N, P, K, etc.) and micronutrients (also called trace minerals). These nutrients are in forms that are readily available for plants.
The benefits of vermicompost go beyond just fertility. Researchers compared the growth of plants fertilized by vermicompost to plants that received the same level of nutrients as provided by synthetic fertilizer. The plants in vermicompost grew better and had better root development. Scientists set out to identify the other benefits of vermicompost.
Vermicompost can improve soil fertility in terms of both physical and chemical properties of the soil. “Physical improvements include better aeration, porosity and bulk density of the soil. Chemical properties such as pH, electrical conductivity and organic carbon content are also enhanced for better plant growth.” Beyond that, the researchers found that vermicompost contains “plant growth-influencing substances” including humic acids, and plant growth hormones (such as auxins, gibberellins and cytokinins). The vermicompost also contained high levels and a high diversity of microorganisms.
However, there can be too much of a good thing. Although moderate levels of vermicompost improved plant growth, excessive levels hindered plant growth. As with excessive levels of compost, the high salt content of vermicompost may be responsible.
The use of vermicompost in organic farming: overview, effects on soil and economics. Su Lin Lim, Ta YeongWu, Pei Nie Lim and Katrina Pui Yee Shak. 2015. Journal of the Science of Food and Agriculture. Vol. 95. pp. 1143–1156
- Janet Wallace