Estimation of soil properties with mid-infrared soil spectroscopy across yam production landscapes in West Africa
P. Baumann,
J. Lee,
E. Frossard,
L. P. Schönholzer,
L. Diby,
V. K. Hgaza,
V. K. Hgaza,
D. I. Kiba,
D. I. Kiba,
A. Sila,
K. Sheperd,
J. Six
Affiliations
P. Baumann
Group of Sustainable Agroecosystems, Institute of Agricultural Sciences, ETH Zurich, 8092 Zürich, Switzerland
J. Lee
Department of Smart Agro-industry, Gyeongsang National University, Jinju, 52725, Republic of Korea
E. Frossard
Group of Plant Nutrition, Institute of Agricultural Sciences, ETH Zurich, 8315 Lindau, Switzerland
L. P. Schönholzer
Group of Plant Nutrition, Institute of Agricultural Sciences, ETH Zurich, 8315 Lindau, Switzerland
L. Diby
World Agroforestry Centre (ICRAF), Côte d’Ivoire Country Programme, BP 2823 Abidjan, Côte d’Ivoire
V. K. Hgaza
Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303 Abidjan, Côte d’Ivoire
V. K. Hgaza
Département d’Agrophysiologie des Plantes, Université Peleforo Gon Coulibaly, BP 1328 Korhogo, Côte d’Ivoire
D. I. Kiba
Group of Plant Nutrition, Institute of Agricultural Sciences, ETH Zurich, 8315 Lindau, Switzerland
D. I. Kiba
Département Gestion des Ressources Naturelles et Systèmes de Production, Centre National de la Recherche Scientifique et Technologique, Institut de l'Environnement et Recherches Agricoles, 01 BP 476 Ouagadougou, Burkina Faso
A. Sila
Land Health Decisions, World Agroforestry Centre (ICRAF), Nairobi, Kenya
K. Sheperd
Land Health Decisions, World Agroforestry Centre (ICRAF), Nairobi, Kenya
J. Six
Group of Sustainable Agroecosystems, Institute of Agricultural Sciences, ETH Zurich, 8092 Zürich, Switzerland
Low soil fertility is challenging the sustainable production of yam and other staple crops in the yam belt of West Africa. Quantitative soil measures are needed to assess soil fertility decline and to improve crop nutrient supply in the region. We developed and tested a mid-infrared (mid-IR) soil spectral library to enable timely and cost-efficient assessments of soil properties. Our collection included 80 soil samples from four landscapes (10 km × 10 km) and 20 fields per landscape across a gradient from humid forest to savannah and 14 additional samples from one landscape that had been sampled within the Land Health Degradation Framework. We derived partial least squares regression models to spectrally estimate soil properties. The models produced accurate cross-validated estimates of total carbon, total nitrogen, total sulfur, total iron, total aluminum, total potassium, total calcium, exchangeable calcium, effective cation exchange capacity, and diethylenetriaminepentaacetic acid (DTPA)-extractable iron and clay content (R2>0.75). The estimates of total zinc, pH, exchangeable magnesium, bioavailable copper, and manganese were less predictable (R2>0.50). Our results confirm that mid-IR spectroscopy is a reliable and quick method to assess the regional-level variation of most soil properties, especially the ones closely associated with soil organic matter. Although the relatively small mid-IR library shows satisfactory performance, we expect that frequent but small model updates will be needed to adapt the library to the variation of soil quality within individual fields in the regions and their temporal fluctuations.