Watersheds are naturally productive but most ecologically vulnerable section of the landscape. Productivity assessment of two contrasting watershed were studied in Amawbia south east, Nigeria using amaranthus as test crop under field and pot experiments. The experiments were arranged in randomized complete block design (RCBD) and complete randomized design (CRD) respectively in managed and unmanaged system of the watershed with NPK at the rate of 150kg/ha. Findings from the study showed significant differences (P < 0.05) among the slopes, managements, slope and management as well as natural environment and NPK in all the parameters assessed. Higher values were recorded in managed system in all the parameters and values obtained from NPK were observed to be higher than the values obtained from natural environment. Natural environment of the four slopes studied in managed plot significantly recorded increased growth and yield of amaranthus than the unmanaged plots. Thus, the findings of the study are evidence that sustainable management of soil and water resources is based on the judicious and scientific management of all landscape units within a watershed. As land degradation beyond the point of no return, pollution and eutropication of water and environment are all traceable to poor and mismanagement of landscape units within a watershed.
Keywords: Amaranthus, Ecosystem, Fertilizer, Natural Environment, management systems, slope
