EVALUATION OF METHODS TO STUDY SOIL EROSION-PRODUCTIVITY RELATIONSHIPS

The objective of this review paper is to compare methods currently use d to evaluate the effects of soil erosion on soil properties and crop yields on cultivated soils. The methods include (i) topsoil removal an d additions, (ii) paired comparisons between eroded phases of soils wi thin a field on a similar landscape position, (iii) analyzing yield da ta for a soil series from many plots in numerous fields with variable management and on different landscape positions, (iv) factor analyses and geostatistics, and (v) simulation models such as Erosion Productiv ity Impact Calculator (EPIC) and Nitrogen-Tillage Residue Model (NTRM) . Each method has inherent strength, weakness, and bins which can resu lt in the measured soil productivity response attributed to erosion be ing potentially confounded with other variables such as landscape posi tion, soil formation and management.