Irrigation of Groundnut with Water of Different Salinity Levels and their Effect on Soil Hydro-Physical Properties and Crop Performance

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March, 2010.
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This study was carried out to evaluate the different levels of salinity on some physical, hydrologic and chemical properties of soil in a greenhouse study. Groundnut was used as a test crop. Different levels of salinity on growth parameters and yield performance of groundnut were also investigated. The study was carried out at Soil Research Institute of the Council for Scientific and Industrial Research (CSIR), Ghana. The soil used was a chromic Lixisol from the Transitional Agro-ecological Zone of Ghana. Three levels of sodicity were used with zero salinity as the control. The experiment was a split plot design with Complete Block Design (CBD), with four replications. In this pot experiment, four seeds were sown per pot and later thinned to two. Saline treatments were imposed by irrigating each pot with water containing varying concentrations of sodium chloride. These concentrations corresponded with Electrical Conductivities (EC) of 2.0 dSm-1, 4.0 dSm-1 and 6.0 dSm-1 respectively with 0.0 dSm-1 as the control. The results indicated that salinity levels consistently increased the bulk density but decreased total porosity and air-filled porosity. Saliniity also consistently decreased soil infiltration rate. Sorptivity and apparent hydraulic conductivity also consistently decreased with increasing salinity levels. Salinity consistently decreased growth and significantly reduced the yield of groundnut. The residual moisture increased with increasing salinity levels indicating reduction in water uptake by the groundnut. Salinity also decreased the Evapotranspiration (ET) of groundnut. The residual nutrient contents of nitrogen, potassium and phosphorus increased as salinity levels increased indicating the reduced ability of groundnut to take up nutrients under high saline conditions. ii Increasing concentration of sodium chloride concomitant increase in sodium concentration in groundnut leaves, which could be associated with nutrient imbalance effect caused by sodicity. Salinity increased the bulk density while it decreased the porosity of soil. It also decreased water entry and movement in soil. Salinity had negative impact on growth and yield of groundnut.
A thesis submitted to the Department of Crop and Soil Sciences, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE,