MOISTURE RETENTION CHARACTERISTICS OF SOILS USED FOR VEGETABLE CROP PRODUCTION IN THE TOLON-KUMBUNGU DISTRICT, GHANA

Abstract

Most soil moisture measurements make use of the direct method with its associated disadvantages. Farmers in the study area particularly use the direct observation and feel methods in the determination of the required moisture level for the most farming activities even though this is subjective and normally inaccurate. This study employed the indirect method (tensiometer and theta probe) if soil moisture measurements and determined the available soil moisture and force of suction of soil water by existing capillary force at different depths and locations. The study was conducted at the University farm of the University for Development Studies, Gung and Gizaa in the Tolon-Gumbungu District. Vegetable crops commonly grown in these areas include Capsicumj spp, LYCOPERSICON ESCULENTUM, Solanum melongena, Abelsoschus esculentus and Hibiscus cannabinus. Ferric acrisols, dysteric planosols and dystric plinthosols are soils commonly found in this area and have varying soil moisture characteristics. An inverse soil matric potential rainfall relationship was determined for all three (3) study areas. Soil suction therefore increased as the soil moisture content increased coupled with lower matric potentials when high rainfall was recorded. A direct relationship was established between volumetric moisture content and rainfall for the study period. Drier periods (dry season) recorded lower volumetric moisture content and increased with the intensification of the rains reachiny its peak in September. August and September 2007, recorded the lowest pF values ranging from 0.43 at Gizaa (40 cm) to 0.80 at 15 cm depth in the University Farm. These indicated a saturated soil condition of the study areas this exerting soil moisture suction stress on the vegetable crops grown. Soil moisture characteristic curves however varied with varying soil texture. Root rot resulting in the lodging of vegetable crops was observed during the period of study. Moisture stress and excessive moisture in the study area resulted in low yields of crops as a result of root stock rotting, plant lodging as well as fruit rotting.