Erosion and Sediment Control
Assessing Quantitative Performance of Biotic Soil Technology versus Topsoil and Compost for Growth Establishment and Soil Health
For decades erosion control professionals have relied on “topsoil” as a starting point to successfully establish sustainable vegetation on construction sites and disturbed lands around the world. With this in mind, practitioners have developed a myriad of specifications ranging from overly simplistic statements such as “the soil shall be capable of sustaining vegetation” to very comprehensive specifications calling for “topsoil” that requires several key physical and biological components making it desirable for vegetation establishment. Highly demanding and specific specifications consistently run into one major impedance – availability. Real topsoil is a vanishing resource and limited availability can dramatically increase material cost when candidate soils must be hauled over significant distances to projects.
Shortages of topsoil have stimulated interest in sourcing functionally equivalent alternatives. Contractors and soil blending professionals have been quick to discover that by incorporating organic materials such as compost into “fill soils” or “dirt” within certain textural and pH ranges, they could “manufacture” soils to meet weaker topsoil specifications. Although these soil blends may meet minimal specifications, they rarely provide the same benefits as true topsoil. Most notably, a minimum percentage of organic matter does not necessarily imply there will be sufficient levels of biological activity. Moreover, these “faux topsoils” may still need to be imported and hauled appreciable distances and then placed upon a defined substrate. This raises the question – is addition of a manufactured soil necessary in all situations?
Biotic Soil Technology (BST) products are engineered to incorporate consistent weed and pathogen free sources of organic materials with potent amounts of biostimulants and biological inoculants to replicate and accelerate early pedogenic processes that often may take years to naturally occur on denuded sites. Key to soil development and resultant soil health is the establishment of sustainable vegetation and subsequent nutrient cycling. BSTs are designed to both accelerate vegetative establishment and develop soils, hence the paradigm shift – “why import soils, when you can build them in place”?
There have been recent studies and many successful projects demonstrating qualitative functional equivalence of BST to topsoil and compost in a variety of climatic conditions, biomes, applications and markets. Few, however, have incorporated requisite replicated randomized plot design, proper sampling and data collection methodology, nor an in-depth compilation of quantitative plot analyses and data to provide scientifically proven conclusions.
This publication will review protocol used to design, monitor and complete triple replicate testing of BST, topsoil and compost with surficial erosion control techniques to include hydraulically-applied erosion control media, base hydraulic mulches and control plots with no erosion protection – totaling 13 separate treatments. The paper will then identify and present results for sample collection techniques used to measure and quantify growth establishment and in situ development of soils to include changes in organic matter and soil respiration as well as bacterial and fungal population counts.