An Improved Soil‐Sampling Procedure for the Prediction of Dissolved Inorganic Phosphate Concentrations in Surface Runoff from Pasture

Abstract
Linear relationships were obtained between the mean concentration of dissolved inorganic phosphate (DIP) in each of several surface‐runoff events and the amounts of inorganic P extracted by 0.1M NaCl from the top 1 cm of soil sampled prior to the event. These relationships were similar for both unfertilized and fertilized, undrained pasture. This contrasted with the data obtained in the previous year for the same surface‐runoff plots, receiving the same treatments, where markedly different linear relationships were obtained using a 0–5 cm soil‐sampling depth. The modified soil‐sampling procedure provides a more generally applicable method of predicting the concentration of DIP in surface runoff from pastures of widely differing P status.