Application of Geographical Information Systems Technology in Soil Fertility Variation Analysis in South-eastern Nigeria

Abstract

The study investigated the fertility status of soil around the River Otamiri watershed in Imo State of South-eastern Nigeria. A Geographical Positioning System was used to geo-reference the area and locate the soil samples, which were collected from 9 sampling points at 2 m depths each. The sample points were 210m, 110m and 10m away from the river channel. The soil samples were air-dried and passed through 2-mm sieves before they were subjected to routine laboratory analyses. Results showed that the soil area was predominantly made of loamy sand particles, with high values ± 98.7% which decreased progressively away from the river. There was increase in available phosphorous upslope compared to downslope, steady decrease in aluminum and hydrogen downslope, while areas closer to the river have less acidic cations. The soil pH ranged from 4.67 ↔ 5.62. Surface soils comprised more of organic carbon content than subsurface soils which decreased from crest to footslope. The soil data also produced low values of total nitrogen and the total exchangeable bases. The results presented the soil as infertile and unfit for serious farming except with conscious enrichment efforts.

Keywords: soil fertility, surface soils, soil samples, geographical information systems, watershed