Abstract
Low nutrient levels in soil are a recognized limitation to crop production. Yet, farmers in certain agro-ecoregions either do not apply fertilizers, apply inadequate amounts, or apply the wrong fertilizers due to a mismatch with the nutrient needs of their soil. In many cases, lack of availability of wet chemistry capabilities contribute to farmers in less developed regions not routinely conducting soil tests prior to fertilizer application. Fortunately, novel technologies and commercial products have become available, providing on-farm, timely, and relatively inexpensive soil and plant nutrient analytical services.
Here, we identified rapid soil and plant nutrient testing technologies, currently in the market, based on a web search, and evaluated the basis for deploying them as alternative nutrient analytical systems. Thirty six of such applications were identified, out of which only 5 are dedicated solely to plant analysis. Collectively, the functioning mechanisms of most of the products were found to be based on colorimetry, spectroscopy or sensor technology. However, in comparison with traditional wet chemistry methods, the accuracy of the products is yet to be fully resolved, given the paucity of data in that regard. Subsequently, we reflected upon the effectiveness of the products in generating relevant information to guide rationale fertilizer recommendations, and in that context discussed the concept of balanced fertilizer regimes that consider soil levels of different nutrients; associated soil factors that determine nutrient bioavailability and actual uptake by crops; and complex farming systems that may undermine the precision and efficiency of fertilizer application.