ABSTRACT
This study was conducted to determine be nutrient status and forms of potassium in farmed soils in the University of Benin Experimental Farm Project., Faculty of Agriculture, University of Benin, Benin City, Nigeria. Soil sample was collected from the Experimental Farm Site and control site at a depth of 0-15, 15-30 and 30-45cm using a soil Auger. Soils collected from each horizon were air-dried, crushed and passed through a 2mm sieve. The sieved samples were analyzed for some physical and chemical properties using standard laboratory procedures. The data obtained were analyzed by Genstat computer package. The difference between the means were separated using Duncan multiple range test at 5% level of probability. The result showed that sand (833.9 g/kg) fraction was predominant in the farm site. The mean pH (4.58) result indicated that higher level of pH was recorded in Experimental Farm Site compared to the control site (4.35). The highest EC value of 127.30µS/cm is evident in the topsoil (0 - 15cm), followed by 113.30 µS/cm at the 15 - 30cm depth, and organic matter content highest at 15 - 30cm (21.20 mg/kg) while the highest total nitrogen mean (1.17 mg/kg) was recorded in the soil at the Experimental Farm Site compared to the control site with mean total nitrogen of 0.48 mg/kg. The mean result showed that the of the amount calcium (Ca), magnesium (Mg) and average phosphorus were higher in Experimental Farm Site than the control site. The result showed that the highest (0.13 cmol/kg) Water soluble potassium (H2OK) was recorded in soil depth of 0 – 15. The mean result showed that exchangeable potassium (Exch K) (0.17 cmol/kg) at the Experimental Farm site is superior to the control site (0.12 cmol/kg). The mean result of Hcl K (0.37 cmol/kg), Acid K (0.13 cmol/kg), Residual K (0.45 cmol/kg) and Total K (1.35 cmol/kg) of the Experimental Farm site were superior to the control site Hcl K (0.3 mg/kg), Acid K (0.12 mg/kg), Residual K (0.39 cmol/kg) and Total K (1.18 cmol/kg) respectively. The result showed that forms of potassium, H20 K, Exch K, Hcl K, Acid K, Residual K, and Total K exhibited positive correlations with EC, organic matter (Org. M), total nitrogen (T. N), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), and average phosphorus (Av. P). It is therefore concluded that soil potassium is needed for complete nutrient supply in farms.
