New Mixing Model Predicts Rooting Media Properties

New Mixing Model Predicts Rooting Media Properties

Growing Media Mixing ModelResearchers at The Netherlands-based Wageningen University & Research have developed a mixing model that predicts the properties of a mix of 2-9 constituents in any growing media ratio. Predicted parameters were EC, pH, nutrients, trace elements, water content, air content, and degradability.

A growing interest in peat alternatives, notably composts, resulted in the renewed demand for a model to predict the effects of mixing potting soil constituents. The goal of the research team was to make such a mixing model that could predict the combination of constituents. The outcome of the model and the results for measurements on the actual mixtures were compared. Most modeled values came to within 5% of the measured values, which is considered acceptable.


The effects of interstitial filling, the filling of pores in one material with smaller particles from another material, were included. PH as parameter could not be predicted but could be replaced with the pH buffer measurement. Easily available water, however, could not be effectively predicted by the model.

In addition, the model shows it is possible to estimate how much of some additives needed to be added. The additives were lime, nitrate, fertilizers, and iron chelates. Lime is administered to increase and stabilize the pH. Nitrate and iron are added to compensate the increased uptake of nitrate and iron by microorganisms. The fertilizers were added to reach the crop specific base dressing. The fertilizers already present in the substrate materials were subtracted.

Learn more at the Wageningen University & Research website.