Differences are illustrated in the table which shows recommendations from four citrus-producing countries in S. America, N. America, Africa and Asia respectively. As can be seen from the table, the quantity of fertilizer applied increases with the age of the tree. The area to which the fertilizer is applied also increases with the age of the tree. Generally where tree-planting holes are used, fertilizer is applied to the surface area of the hole because not many roots will grow beyond it. The crop is planted on loam soils which are relatively infertile but have enough organic matter to give a cation exchange capacity of about 7.
Young trees appear healthy and well fertilized.
Most plantings are unirrigated. Trees begin producing in the third year. Florida, USA The crop is grown on sandy soil with very low fertility and organic matter, and a cation exchange capacity of 2-3. Despite being in the humid region with adequate rainfall, irrigation is practised because of the sandy soils' low water-holding capacity. C te d'Ivoire Cultivation is similar to that of many developing countries where much of the organic manure and mineral fertilizer used is incorporated in the planting hole.