Hydrological and Physical Changes of Soils Under Cocoa Plantations of Different Ages During the Dry Season in the Transition Zone of Ghana

Abstract

The study was conducted at the University of Education, Winneba, Mampong Campus from October, 2007 to March, 2008 to assess the hydrological and physical changes that take place in soils under cocoa plantations of different ages as climate changed through the dry season. The treatments were T₁ (control, representing an adjoining grass fallow land), T₂ (5-year old cocoa plantation), T₃ (4-year old cocoa plantation) and T4 (3-year old cocoa plantation). The parameters measured were: Bulk density, Total porosity, organic matter, gravimetric moisture content, potential evaporation and Net Litter Accumulation (NLA) of the plants. From the results, T₂ recorded the highest gravimetric moisture content, porosity, litter fall, organic matter and lowest bulk density and potential evaporation. T₁ recorded the lowest and highest values for gravimetric moisture content (3.5%) and evaporation loss of water (249.0mm), respectively, at day 84. Correlation analysis revealed that soil moisture was highly influenced by bulk density, total porosity, potential evaporation and net leaf litter accumulation. Soil moisture storage negatively correlated with potential evaporation (r = -0.987) and bulk density (r = -0.985) but positively correlated with Total porosity (r =0.984) and net litter accumulation (r = 0.941). The proper manipulation of these parameters would ensure good soil moisture retention and better adaptations of cocoa to unfavourable conditions driven by climate change in the Transition Zone of Ghana.

Keywords: Gravimetric moisture, potential evaporation, porosity, leaf litter, correlation