MINERAL DEFICIENCIES AND FERTILIZATION OF COASTAL REFORESTATIONS IN BENIN, WEST AFRICA

In the coastal zone of Benin K and P deficiencies are a common phenomena in reforestated Eucalyptus camaldulensis as well as in young stands of Casuarina equisetifolia (filao) even with initial fertilization during planting. Mineral disorders (N/K-ratios of about 10) were also described for Leucaena leucocephala used in alley cropping trials. Special attention was focused on the development of deficiency symptoms of young filao, on which red leaves are an advanced stage of leaf yellowing. This phenomenon is induced by N-, P- and K-deficiency. Due to the small CEC of the sandy soils fertilization with (NP)K may quickly enhance Mg-deficiency, as shown for coconut with foliar levels of only 0.03-0.05% Mg. To get a better understanding of these relationships fertilization trials were started. © 1990 Kluwer Academic Publishers.