A Luenberger soil-quality indicator

This paper discusses how a quality indicator can be constructed as a Luenberger indicator using directional distance functions. This leads to a suggested formula for aggregating individual soil quality attributes into an indicator. The method is illustrated using crop trials data from Western Australia. The approach presented is theoretically consistent and may provide a better alternative to many of the ad hoc procedures used to construct soil-quality indexes in the soil science literature. Our approach also addresses shortcomings related to quality indicators previously proposed in the productivity literature using Malmquist indices.