INTERPRETATION OF LEACHING UNDER MULTIPLE FERTILIZER APPLICATIONS

Simple theory has been developed and illustrated elsewhere which allows estimation, first, of the mean depth of solute penetration from any sequence of infiltration and evapotranspiration events, and second, of the apparent dispersion about this mean depth used as a Lagrangian coordinate system. This theory was used to analyze and interpret the time patterns of leachate concentrations of NO3-N and Cl of a field lysimeter with a potato crop receiving 4 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 quantified the leaching loss from each fertilizer application.