While the meetings and education sessions at events like Great Lakes Expo are valuable and informative, the posters sharing research from graduate students shouldn’t be ignored. They provide bite-sized nuggets of larger projects worth looking into.
For example, Taylor Mauch, a graduate research assistant, and Dr. Ajay Nair, an associate professor, both with the Department of Horticulture at Iowa State University, shared their work, “Differing biochar application rates in combination with varying fertility treatments on greenhouse transplant production.”
The objectives of their study were twofold: To identify the biochar addition to soilless media at varying rates (by volume) that will produce high quality pepper transplants, and to identify the potential interactions between biochar and fertilizer application rates and how they impact plant growth.
They explained that biochar is a carbonaceous material made from biomass that’s been decomposed in high temperature/low oxygen environments. It has high cation exchange capacity (a measure of the total negative charges within soil that adsorb plant nutrient cations such as calcium, magnesium and potassium), high surface area and high porosity. These are all important, as they allow for greater opportunity for nutrients to bind to the surface of biochar.
That means that biochar can act a bit like a storage container for nutrients, theoretically allowing plants to draw from it and take into their systems. Mauch and Nair’s hypothesis wondered if varying biochar rates, combined with various fertility treatments, would result in impacts on overall plant growth.
The biochar the team tested came from a base of mixed hardwoods. It was combined with a soilless substrate in equal parts in mason jars. Red bell peppers were seeded in trays before being transplanted in the jars, and fertility treatments were applied to the seedlings in weeks 4 – 7.
Biochar percentages for total volume were either 0%, 20% or 40%. There were also four levels of fertilization treatment studied – either no fertilization was applied; 75 ppm nitrogen was applied for the four weeks; 75, 150, 150 and 75 ppm N was applied during weeks 4 – 7; or 150, 300, 300 and 150 ppm N was applied during weeks 4 – 7.
To measure the growth of the pepper plants, they looked at stem diameter and height; the medium’s pH and electrical conductivity (EC); chlorophyll content; root length, surface area, diameter and volume; and root and shoot biomass on a dry weight basis.
What they discovered was that biochar impacted medium EC at later dates, especially at the 40% volume. However, root biomass did increase with increasing fertilizer rates. Biochar also impacted plant height at all dates and chlorophyll content at later dates. The fertility applied impacted all plant growth measurements conducted.
Broadly put, biochar may help plants grow taller, and used judiciously in combination with fertility treatments, it may help plants take up some nutrients better.
Look for more poster presentation breakdowns in future editions of Country Folks Grower.