QUARRY STONE DUST EFFECTS ON SOIL PHYSICO-CHEMICAL PROPERTIES AND EARLY TREE GROWTH OF GMELINA ARBOREA (Roxb) AND TERMINALIA IVORENSIS (A. Chev.)

Abstract

This study examined the nutrient content in quarry dust and the implications of the dust on the surrounding soil and early tree growth of Gmelina arborea and Terminalia ivorensis. The study was carried out in three randomly selected quarry sites in Ondo State, Southwest Nigeria. The sites are Ondo State Asphalt Company (OSAC) Ondo Road Akure, Ebenezer Mining and Ceramic Ind. LTD, Km 5, Akure-Owo Express Road Akure and Dortmund and Company Nig LTD Iju-Itaogbolu. Collection of rock dust and Topsoil samples were carried out at the crushing point in the quarry sites and at the 50m and 100m into the adjoining forest to the crushing point. This is for the laboratory analyses of physical and chemical content of stone dust to assess its impacts on soil properties and fertility. The essential nutrient elements assessed were carbon, nitrogen, phosphorus, potassium, and calcium and the dust particle size. The species planted were for the study of effect of quarry dust on the early tree growth. The tree seeds were hand picked, prepared and seedlings raised in the nursery. Two hundred and sixty (260) seeds (10 seeds per treatment) of the species were planted using four different percentage ratios (0:100, 25:75, 50:50, 75:25, 100:0) of topsoil and quarry dust combination. The seedlings were nurtured for three months and the tree seeds germination periods and the seedlings’ growth parameters such as; height of stem, number of leaf, stem diameter from the 4th week to 12th week were taken. Dry biomass was calculated and the equivalent carbon and carbondioxide was derived. The results of the physical properties show that the rock dust and the topsoil have higher percentage proportion of sand, followed by percentage proportion of silt and least percentage proportion of clay. Result showed that the pH values for the rock dust, the site sample topsoil and the FWT nursery topsoil (Control) varied between 4.86 and 7.33. For other nutrients, Na, P, Organic Carbon, Organic Matter and N concentrations were lower in the site location than in the control while K and Ca concentrations were higher in the site location than in the control. The growing media has beneficial effect on G. arborea. For seed germination 25% rock dust mixed with 75% top soil is the best medium as it produced 100% seed germination. The 100% rock dust produced the least seed germination results. Significant differences were observed among the different treatments with regards to seedling growth characteristics. The maximum numbers of leaves are recorded in 50% rock dust (21 and 6), maximum seedling stem diameter (5mm and 0.6mm) and highest seedling stem height (32.3cm and 5.7cm) for both G. arborea and T. ivorensis respectively. The study therefore concludes that growing media significantly influenced the seed germination and seedling growth parameters of G. arborea in which medium of rock dust + top soil (50:50) was the best. Finally, it is recommended that rock dust should be used as a soil amendment in growing media for higher germination percent and satisfactory seedling growth of G. arborea and T. ivorensis.