Soil Physical and Chemical Properties of Cacao Farms in the South Western Region of Cameroon

Aims: To evaluate important physical (texture) and chemical [(pH, N, C content, exchangeable bases (K, Ca, Mg), exchangeable Al, CEC and % BS] properties of major cacao (Theobroma cacao L) growing soils of the South Western Region of Cameroon.

Place and Duration of Study: Cocao farms in the South West Region of Cameroon and the Institute of Agricultural Research For Development (IRAD) Ekona, Soil and Plant Analytical Laboratory from March to December 2013.

Methodology: Soil samples were collected from cacao plantations in the humid forest zone of South West Cameroon. Locations were referenced using a GPS (Model Garmin 600). Seventeen matured farms which ranged in size from 2 to 5 ha were selected for this study. Composite soil samples were collected using soil auger at 0-30 cm depth. These soils were analyzed for particle size, pH and exchangeable cations (Ca2+, Mg2+, K+ and Na+). The organic carbon, Total Nitrogen, Cation Exchange Capacity (CEC), Effective Cation Exchange Capacity (ECEC), %BS, and %Al saturation were also determined.

Results: The soils of the studied sites were slightly acidic, with pH (H2O) range of 4.58-6.46. The soils were clayey in texture, ranging in clay content from 19.79 to 77.04% and sand content from 4.25 to 64.42%. The total nitrogen levels for all the studied sites ranged between 0.11 and 0.82% with an average of 0.30%. Soil organic carbon levels were quite good for crop production (1.02 – 7.75 %). The exchangeable potassium and magnesium levels ranged between 0.11–0.67 cmol/kg and 0.31–2.41 cmol/kg respectively. The exchangeable calcium levels in these soils ranged from 1.11–18.00 cmol/kg while available phosphorus levels ranged between 0.01-26.00. mg/kg.

Conclusion: The soils evaluated were generally adequate in required nutrients but could become deficient in nutrient content in the near future especially as there is no fertilizer application being practiced and further increase in yields might deplete the essential nutrients and such a situation could lead to soil infertility in this region. Therefore it is essential to formulate and follow best nutrient management strategies for this cacao growing region to maintain adequate soil nutrient status for sustainable cacao bean production.