IMPACT OF TOPOSEQUENCE ON SOIL MICRONUTRIENTS IN TULA, KALTUNGO LOCAL GOVERNMENT AREA, GOMBE STATE, NIGERIA

Abstract

Micronutrients are element need in small amount but its deficiency can lead to a major constraint to soil productivity. Toposequence plays a major role in influencing soil fertility distribution. This study aims at assessing the effect of toposequence on soil micronutrients in Tula. Soil sample were collected from upper, middle and lower slope at the depth of 0-15 cm and 15-30 cm and analyzed for DTPA-extractable micronutrient using standard procedures. The soils were all rated very high in iron (Fe), Manganese (Mn), Copper (Cu) and Zinc (Zn) contents. The results shows mean Fe values in the lower slope was24.1 mg/kg, middle slope was 16.0 mg/kg and upper slope was 9.9 mg/kg and subsoils were significantly (p < 0.01) higher than surface soils. The mean Mn values in the lower slope was20.6 mg/kg, middle slope was 17.5 mg/kg and upper slope was 14.2 mg/kg. The mean Cu values in the upper slope was 4.2 mg/kg, middle slope was 3.9 mg/kg and lower slope was 3.76 mg/kg. The mean Zn values in the lower slope was 4.2 mg/kg, middle slope was 3.9 mg/kg and upper slope was 3.76 mg/kg. Extractable Zn in subsoils were significantly (p < 0.001) higher than surface soils. Extractable Fe and Mn increase down the toposequence while Cu and Zn decreases down the toposequence. All the micronutrients increased with soil depth. The toposequnces were all adequate in micronutrient but there are possibility of micronutrient toxicity which call for caution for sustainable development.