Affordable rapid field-based soil tests

Accurate soil nutrient data allows farmers to match fertiliser inputs to soil and crop requirements. However, currently available soil test methods require a trade-off between analytical precision and practical application.

Laboratory analysis provides accurate, quantitative results, but depends on costly instruments, trained staff, and extended turnaround times. For most farming operations, these constraints make regular soil monitoring economically unfeasible, which limits the capacity to track changes in nutrient status and respond as soil conditions change through the season.

In-field test kits address the constraints of cost and turnaround but offer considerably lower precision. Most are colourimetric, relying on a colour change to indicate nutrient concentration. The reading depends on the user’s colour perception and on how well they prepare the sample, both of which introduce variability – the same sample can give different results depending on the operator. These kits also report an approximate concentration range rather than a quantitative value, which provides insufficient precision to guide fertiliser decisions.

In-field soil testing would allow farmers and agronomists to assess soil nutrient status in the field and make immediate, evidence-based decisions on soil management and fertiliser use, without the cost and time of laboratory analysis or the imprecision of existing field test kits.