Assessment of Soil Macro and Micronutrient Status in Relation to Date Palm Plantation (P. dactylifera) Growth Variabilities under an Agrisilvicultural System in Yola, Nigeria
A.A. Gujja *
Department of Forestry Technology, Yobe State College of Agriculture, Science and Technology, Gujba P.M.B-1104, Damaturu, Nigeria.
E. E. Dishan
Department of Forestry and Wildlife Management, Faculty of Agriculture, Modibbo Adamu University, Yola, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Soil nutrient balance is an important factor influencing the growth and productivity of date palm under agroforestry-based production systems. This study assessed soil macro- and micronutrient status in relation to growth variability of date palm (Phoenix dactylifera L.) within an agrisilvicultural system at Modibbo Adama University, Yola, Adamawa State, Nigeria. The plantation was stratified into high-, medium-, and low-growth zones based on observed variation in tree performance. Soil samples were collected from surface and subsurface layers at five auger points within each growth zone and analysed for selected macronutrients and micronutrients using standard laboratory procedures. Total nitrogen was determined using the Kjeldahl method, available phosphorus by Bray-1 extraction, potassium by flame photometry, exchangeable calcium and magnesium by ammonium acetate extraction, and micronutrients by atomic absorption spectrophotometry. Data were analysed using one-way analysis of variance, and mean separation was conducted using the least significant difference test at the 5% probability level. The high-growth site recorded 0.1504% nitrogen, 10.399 mg/kg phosphorus, 0.6514 cmol/kg potassium, 4.5080 cmol/kg calcium, and 0.7922 cmol/kg magnesium. The medium-growth site recorded 0.1342% nitrogen, 10.288 mg/kg phosphorus, 0.6154 cmol/kg potassium, 4.2076 cmol/kg calcium, and 1.4564 cmol/kg magnesium, whereas the low-growth site recorded 0.1212% nitrogen, 9.9698 mg/kg phosphorus, 0.5686 cmol/kg potassium, 3.6626 cmol/kg calcium, and 2.3366 cmol/kg magnesium. The reported statistical results indicated significant variation in nitrogen and magnesium among growth zones, whereas micronutrient concentrations showed no significant differences. The findings suggest that variation in date palm growth within the plantation may be more closely associated with macronutrient availability and cation balance than with micronutrient deficiency. Site-specific soil fertility management and periodic soil monitoring are therefore recommended.
Keywords: Soil fertility, macronutrients, micronutrients, date palm, Phoenix dactylifera L., agrisilvicultural system, growth variability, nitrogen, exchangeable cations