Assessment of the Nutrient Status of Soil under Chromolaena odorata L. (Siam Weed) Fallow in Moniya, Oyo State Southwestern Nigeria

In Nigeria, soil fertility restoration for improved agricultural production is a recurrent issue of immense importance mostly with her ever increasing population currently above 150 million. Therefore, identifying sustainable ecological practice to improve soil fertility is one of the surest ways to enhance food security. The study examined the trend in soil nutrient under the canopy of Chromolaena odorata of zero, 6 months, 1 yr and 2 yr fallows. The grid system of sampling was employed to collect soil samples from ten quadrats of 5m x 5m in each of the Chromolaena fallows. Result showed that C. odorata, a plant of secondary succession had significant effect on the buildup of nutrients in the soil, as the contents of soil properties under the canopy of C. odorata progressively increased with the age of fallows, which perhaps was affected by the increase in Chromolaena plant and cover. The pH level of soils under the canopy of C. odorata especially in the 2nd year fallow considerably favoured the increase in the contents of essential elements in the soil. However, to improve soil fertility, the study suggested that C. plantshould be planted along with staple crops to help minimize nutrient loss, and also, fallows with C. plantsshould be allowed for a reasonable number of years to facilitate nutrient accretion before cultivation.