Interpretation of leaching under multiple fertilizer applications
Simple theory has been developed and illustrated elsewhere which allows estimation, firstly, of the mean depth of solute penetration from any sequence of infiltration and evapotranspiration events, and secondly, of the apparent dispersion about this mean depth used as a Lagrangian coordinate system. This theory was used to analyse and interpret the time patterns of leachate concentrations of NO3-N and Cl of a field lysimeter with a potato crop receiving four fertilizer applications and numerous inadvertent N and Cl applications by irrigation with groundwater. The assumption of superposition of estimated solute concentrations was employed in the analysis, yielding results consistent with the data. The analysis has quantified the leaching loss from each fertilizer application.