Fertilization and Soil Fertility Management under Citrus Cultivation: A Global Review with Special Emphasis on Côte d'Ivoire

Abstract

Citrus is among the most widely cultivated fruit crops in the world, occupying diverse pedoclimatic zones ranging from Mediterranean and subtropical regions to humid and sub-humid tropical belts. Sustained productivity in citrus orchards depends heavily on balanced fertilization and sound soil fertility management, given the crop's substantial and continuous nutrient demand, its perennial rooting habit, and its sensitivity to soil acidity, salinity and micronutrient imbalance. This review synthesises the global literature on nitrogen, phosphorus, potassium, secondary and micronutrient management in citrus, alongside organic and biological approaches such as composting, biochar amendment, arbuscular mycorrhizal inoculation and cover cropping, and examines precision diagnostic tools including leaf and soil critical nutrient levels. Particular attention is given to the constraints of acidic, weathered tropical soils typical of West Africa, and the review draws together the sparse but growing evidence on citrus and associated tree-crop nutrient management in Côte d'Ivoire, situating it within the broader framework of integrated soil fertility management developed for sub-Saharan African smallholder systems. The review finds that while nutrient physiology and diagnostic thresholds are increasingly well characterised in major producing countries such as Brazil, China and the United States, citrus-specific agronomic research remains scarce in West Africa generally and in Côte d'Ivoire specifically, where citrus is grown predominantly as a secondary or shade crop within cocoa- and food-crop-dominated farming systems. Evidence from related tree crops and vegetable systems in the country indicates widespread soil fertility decline, limited fertilizer access and near-absence of leaf or soil diagnostic practice among smallholders. The review concludes by outlining priority research and extension needs for translating global citrus nutrition science into locally adapted, integrated fertility management recommendations for Ivorian growers.