SOIL VARIABILITY IN MAP UNITS DELINEATED BY AERIAL PHOTOINTERPRETATION - A CASE-STUDY IN ANAMBRA STATE, NIGERIA

The variability of five soil series developed in sedimentary formation s in southeastern Nigeria and mapped from aerial photographs was inves tigated in relation to texture, soil reaction, organic carbon, total n itrogen, exchangeable bases, exchangeable acidity, cation exchange cap acity and available phosphorus. Air photo delineation of the five soil series was based on terrain physiography alone. Most of the soil seri es were very variable in available phosphorus, but the coefficients of variation for other soil properties were less than the 33% threshold adopted for within-series homogeneity critical for land use management . Soil series mapping at 1:50 000 scale based on aerial photographs is therefore a cheap, rapid technique. which gives a satisfactory basis for land management to improve productivity and decrease soil degradat ion in Nigeria.