Effect of some modification of extraction technique on extractable p in soils of South West Nigeria

Abstract

Abstract In Nigeria and in some other tropical countries routine soil testing is at its infancy, therefore research into handling and processing techniques is very essential. For the investigation being reported, thirty surface (0–15cm) soils having different cropping histories and variable levels of P were collected from different ecological zones of South Western Nigeria and the following techniques using Bray's P1 and NH4F.HF solutions were investigated; shaking time, type of shaker, length of shaking, positioning of bottles in the shaker, lag period before filtering after shaking and time lag after colour development before P reading. The extractable P from all these techniques were correlated with P uptake in the greenhouse. The results indicated that 5 minutes shaking gave the best correlation with uptake (r= 0.91**) for Bray's P1 and 1 minute for NH4F.HF (r= 0.88**). Neither vertical nor horizontal placement affected the extractable P, but stirring gave a non‐significantly lower correlation. Lag pe...