| Institution: | 1. Institut de l'Environnement et de Recherches Agricoles (INERA), Département Gestion des Ressources Naturelles et Systèmes de Production, Centre National de la Recherche Scientifique et Technologique, Ouagadougou, Burkina Faso
Laboratoire d’Étude et de Recherche sur la Fertilité du Sol, Université Nazi Boni, Bobo-Dioulasso, Burkina Faso;2. Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics, University of Kassel, Witzenhausen, Germany;3. Institut des Sciences de l'Environnement et du Développement Rural, Université de Dédougou, Dédougou, Burkina Faso;4. Institut de l'Environnement et de Recherches Agricoles (INERA), Département Gestion des Ressources Naturelles et Systèmes de Production, Centre National de la Recherche Scientifique et Technologique, Ouagadougou, Burkina Faso;5. Soil Biology and Plant Nutrition, University of Kassel, Witzenhausen, Germany |
| Abstract: | Background Little is known about the effects of gypsum application to remediate saline–sodic soils in the tropics and the role of microbial indicators in soil reclamation. Aims Our study aimed at (1) remediating a highly weathered, irrigated sodic Lixisol under prolonged urban crop production by clean water and gypsum application and (2) to determine the remediation effects on soil microbial indices. Methods A three-factorial on-farm experiment with maize (Zea mays L.) was used to study effects on soil microbial biomass of (1) soil degradation at two levels of salinity, (2) irrigation with clean water and wastewater, and (3) the impact of added gypsum during a typical growing season. Results At the high-degradation site, the 0.5 M K2SO4 extractable carbon (C) content was 40% higher than at the low-degradation site. In addition, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) were 20% lower than at the low-degradation site, while fungal ergosterol was even 40% lower, leading to a 33% lower ergosterol/MBC ratio. Wastewater irrigation increased MBN but decreased ergosterol content at the low-degradation site while having no effect at the high-degradation site. Gypsum amendment led to higher MBN at the low-degradation site but to lower MBN at the high-degradation site. Gypsum amendment always increased the ergosterol content whereby this increase was stronger at the low-degradation site, especially in combination with wastewater irrigation. Conclusions From a microbial perspective, high soil degradation levels should be avoided by treatment of a saline–sodic wastewater prior to its use for irrigation rather than relying on future remediation strategies of affected field sites. |
