Soil Fertility

Randomized survey experiments implemented in Ethiopia and Uganda have tested the relative accuracy and cost effectiveness of soil fertility assessment based on farmer reporting and infrared spectroscopy-based lab analyses vis-à-vis wet chemistry—the gold standard in soil science. The empirical evidence has showcased the systematic error in farmer reporting and has lent support to the use of infrared spectroscopy-based techniques that are significantly cheaper compared to conventional wet chemistry-based ones. The results from our experiments are featured in working papers and peer-reviewed journal articles and have informed our Guidebook on soil fertility assessment in large-scale household and farm surveys. Ongoing methodological research efforts are now assessing the feasibility and accuracy of low-cost, handheld spectrometers for in-situ soil fertility assessments, without having to transport soil samples to centralized locations for lab analyses.