Physicochemical Soil Analysis of Rejuvenated Cocoa Plantation Farms in Obaagun Area of Osun State

Abstract

Theobroma cacao, which is also known as cacao tree is an important commercial plantation crop of the world used in the production of a variety of products such as cocoa powder, chocolate products, beverages, butter, biscuits, wine, soap, cream, cocoa bread, livestock feeds among others. This study evaluated the soil quality of rejuvenated cocoa plantation farms in Obagun area of Osun state, it compares the soil qualities and properties of these cocoa plantations and determine if the soils in the area are well suitable for cocoa cultivation. Twenty-four (24) soil samples each were collected from 2 cocoa plantations (A and B) of similar ages and agricultural practices. The samples were collected from the depths of 0-15cm and 15-30cm from the two sites respectively. The physical properties were analyzed to know the percentage of sand, clay and silt. The chemical properties were analyzed for particle sizes, pH, hydrogen, organic carbon, organic matter, total nitrogen, available phosphorus, cation exchange capacity, base saturation, sodium, potassium, calcium, magnesium, and the heavy metals were also analyzed for zinc, iron, manganese, copper, lead, cadmium, chromium, and cobalt. When analyzing the physical properties of the two sites, it was observed that silt as the highest percentage of soil particles with 79.72% on site B at a depth of 0-15cm and clay as the lowest percentage of soil particles of 6.58% at a depth of 0-15cm on site B. Analyzing the chemical properties on both sites, it was observed that base saturation as the highest percentage with a value of 96.94% on site B at a depth 0-15cm and Hydrogen as the lowest percentage of 0.10 on site B at a depth of 15-30cm. The presence of heavy metal was also evaluated, it was observed that zinc as the highest value of 0.93mgkg-1 on site A at a depth of 0-15cm and both copper and chromium are absent on site A at a depth of 15-30 cm. The long-term residence of the cocoa plantation on the soil resulted in the decline of micronutrients in the soil. There is need for the soil nutrients to be replenished to ensure continued good production of the cocoa plantation.