Physical and Biochemical Characteristics of Soil in a Watershed of the Valley of Oueme: A Rice-based Agroforestry System in the South of Benin

Abstract

The present study aimed to assess the sustainability of rice cultivation in regard to soil physical and biochemical characteristics within the watershed of the Valley of Oueme. by promoting agroforestry in rice-growing systems. For that concern, four kinds of areas were showcased for rice cultivation: Adjido. Agondo. Dame, and Houedomey. Eighty-nine thoughts of farmers on their knowledge of involvement of trees in field production were assessed. Soil samples were collected into rice fields and near of the “under trees” at 0-20 cm alongside the village of Hetin-Houedomey from April to June 2023. It was conducted into some of pieces of plots of lowland rice field to study soil physical and chemical properties. Spores’ density of Arbuscular Mycorrhizas Fungi (AMF) in that soil and their diversity were assessed. A correlation test indicated regarding quantities of clay, silt, and sand, there is a predominance of clay at the “under trees”, and in the fields, that tends to disappear little by little as we move away from trees. The pH (water) of the soil sampled is acidic and varied from 4.37 to 5.44. For chemical analysis, the average rate of total nitrogen varied from 0.218% to 1.476%. The concentrations of available phosphorus in the Valley of Oueme varied from 2 to 7 cmol/kg that revealed weak. Soils appeared to be rich in exchangeable potassium (0.21 and 1.1 cmol/kg) with the highest proportion observed under the tree in the higher topographic altitudes from the village of Dame. The Cation Exchange Capacity (CEC) for its part varied between 11.36 and 59.68 cmol/kg, and with the highest value that is in higher topographic altitudes at the Adjido county. Sixteen Glomus species of AMF were identified and the Glomus multisubstensum was the most abundant. The community of AMF was mostly diversified in the “under trees” soil, according to the Shannon index H = 5.5.