Land use and irrigation effects on soil chemical and biochemical properties: Consequences for rice production in Sahelian West Africa
The Office du Niger (ON) in Mali is one of the largest irrigation schemes in West Africa. In recent years a trend toward increased alkalinization and salinity due to poor irrigation, drainage, and fertilization practices has plagued the ON. To evaluate soil degradation in the ON, enzyme activities were measured among four agronomic treatments of a field trial established to measure the impact of fertility and irrigation practices on rice production. The properties used to evaluate soil quality include: pH, electrical conductivity, fluorescein diacetate activity and dehydrogenase activity. While no significant difference was observed among the four agronomic treatments, a significant difference in soil quality was found between the treated soils and the non- impacted soils. On average, the treated soils had a pH of 8.5 and an electrical conductivity of 427 mS/m. Increasing pH and electrical conductivity were both negatively correlated with microbial enzyme activities.