ICRAF-Working Paper 2000-3

Abstract

Using diffuse reflectance spectrometry, we tested whether light reflectance measurements of soil could detect changes in soil quality resulting from 18 years' of soil management in a long-term experiment. Soil reflectance explained a high proportion (>70%) of the variance in soil carbon and exchangeable nutrients. Soil reflectance predicted extractable phosphorus better in plots without fertilizer than with fertilizer addition. Soil reflectance also explained much of the variation in organic N fractions, including microbial N. Long-term average maize and bean grain yields were strongly related to soil reflectance. Diffuse reflectance spectrometry can provide a rapid and cheap integrated indicator of soil quality for crop production for use in precision agriculture .