Profile Distribution of various micronutrient cations in Teaching and Research Farm of Centre for Dryland Agriculture, Bayero University Kano

Abstract

Micronutrients are nutrients required by plants in small quantities, and are essential for optimal plant growth and development. They play a crucial role in various physiological processes, contributing to increased crop yield and quality. The research was carried out at the Centre for Dryland Agriculture to assess the status of micronutrients across different soil profiles. Five soil mapping units were delineated, and two soil profiles were established in each unit. Soil profile descriptions followed the USDA Soil Survey Manual, and both disturbed and undisturbed samples were collected for laboratory analysis. The study found that iron (Fe) levels were generally rated low to moderate, while zinc (Zn), manganese (Mn), and copper (Cu) ranged from moderate to high across all mapping units. Zinc levels extracted with HCl were higher than those extracted with DTPA in all units, except mapping unit DS, where no consistent trend was observed in pedons DS1 and DS2. The distribution of Zn and Mn generally showed inconsistent decreases with depth for both HCl and DTPA extractions. Moderately higher HCl-extractable Cu values were observed in the surface horizons of pedons GH2 and US1 (1.84 and 1.41 mg kg⁻¹, respectively), while slightly elevated DTPA-extractable Cu was recorded in profiles BN1, DS1, and US1. HCl-extractable Fe was mostly low (<2.5 mg kg⁻¹) in surface horizons but reached moderate levels (2.5–5 mg kg⁻¹) in pedons GH2 and US1. Overall, DTPA-extractable micronutrients were rated moderate to high and were generally higher than those extracted by HCl. The findings highlight the variability of micronutrient distribution across soil depths and emphasize the need to carefully monitor the application of micronutrient-bearing amendments to prevent potential toxicity.