ABSTRACT
Magnesium (Mg) is one of the macro-nutrients needed by plants for growth. The availability of Mg to plants depend on several factors including it’s forms and distribution.
The study was carried out in Orlu soil series to determine the forms and distribution of Mg as well as the relationship between the forms of Mg and some soil properties. Soil samples were collected in three replications from four depths 0 – 30 cm, 10 – 30 cm, and 30 – 60 cm, 60 – 90cm, 90 – 120cm) making a total of 12 soil samples. The selected physical and chemical properties were analysed using standard laboratory operating procedures, the forms and speciation of Mg were determined by sequential fractionation and read using the Atomic absorption spectrophotometer (AAS), while the relationship between the forms of Mg and selected soil properties was determined by simple linear correlation method using Gentat Statistical tool.
The results revealed that the soils were sandy and moderately acidic (5.60), the organic carbon total nitrogen, available P were within normal range for crop production while the Ca, Mg, Na, K and exchangeable acidity were not significantly different across the soil depths but however had mean values of 0.97, 0.25, 0.08, 0.27 and 0.47 cmol/kg, respectively. The form and distribution of Mg showed that various forms of Mg occurred in the soil with total Mg as the highest form with a mean value of 73.44 cmolkg-1 and closely followed structural Mg which serves as residual form with mean value of 60.722 cmolkg-1. The forms of Mg strongly correlated amongst one another indicating a dynamic relationship between one form and another. It is recommended that the soil pH levels be maintained and farming practices that will improve water soluble and exchangeable forms of Mg should be adopted to maintain adequate supply of available Mg to crops.
