LABORATORY MEASUREMENT AND MODELING THE EFFECTS OF MULCHING AND FURROWING ON POSTHARVEST SOIL-WATER EROSION ON POTATO LAND

A laboratory experiment was run on a short length of reconstructed pos t-harvest potato furrow to facilitate evaluation of runoff and soil er osion parameters for modelling 'cool season' soil loss from potato lan ds. The experiment comprised the use of a cold-room facility to evalua te the separate and integrated effects of a furrow side (interrill) an d furrow bottom (rill) erosion on a 3.15 m long section of furrow subj ected to prior freeze-thaw cycling. A factorial arrangement was run wi th four replications of three treatments comprising bare and straw-mul ched surfaces at slopes of 3, 5, and 7%, under sequential 20 min simul ated rainfall applications of 47 and 94 mm/h. Sediment flux was separa tely measured on two sections of furrow side and on the furrow bottom during each rainfall application. Flow velocity was measured in the fu rrow bottom using the dye method. The straw-mulch cover factor for fur row side erosion was 0.21 for the lower intensity rainfall and 0.44 fo r the higher intensity. However, the greatest effect of the straw mulc h was in diminishing rill erosion in the furrow bottom. An example is presented illustrating the use of parameters calibrated from this and previous experiments to facilitate modelling of soil loss from fur row s of practical field length using the COSSEM simulation model.