Biological soil amendments offer the possibility to increase plant root vigour, thus enabling more efficient nutrient uptake greater above-ground plant growth and possibly higher yields. The paper presents three examples of studies done on fodder, apples, and macadamia nuts in South Africa. Additionally, it presents the unique challenges that bicarbonates pose to the utilisation of soil amendments in elevated pH soils. Through the utilisation of biological soil amendments, fodder yield was improved by 51% on average. Marketable apple yield was slightly lower when using biological soil amendments but coincided with significantly less fertiliser used. In macadamia orchards, the measured soil health scores were three to four times greater than in the control orchards. Bicarbonates cause the precipitation of plant nutrients in the rhizosphere as well as on the root surface, hampering its uptake and thus initiating plant stress. The application of organic carbon-based amendments aided in dissolving and leaching these salts, thus unlocking the possibility for more efficient application of biological soil amendments. The results presented here offer a valuable reference on the application of biological soil amendments in the Global South and the unique challenges faced in this predominantly semi-arid environment.
Huyssteen et al. (2025) studied this question.