Validating equations to estimate subfactor ciii for corn residue cover

Erosion is one of the main causes of soil degradation. Model validation is a vital step in developing a valid and applicable tool to predict soil erosion. The aim of this study was to evaluate models that predict the cover and management subfactor (CiII) for interrill erosion. A full factorial design was used, with five doses of corn residue (0; 0.05; 0.15; 0.40 and 0.80 kg m-2), four slope gradients (5.2%; 10.6%; 15.3% and 36.4%) and two repetitions, under simulated rainfall. Di and the CiII were assessed in 0.5 x 0.75 m experimental plots, with recently tilled soil. Soil loss at a 5.2% slope gradient with no soil cover was 458.30 kg ha-1, which could be lowered to 67.13 kg ha-1 by using 90 % cover with corn residues. The soil lost in the treatment without cover at a 36.4% gradient could be reduced 7 times by adopting 90% soil cover. The equations CiII = e -2.50 CS/100, CiII = e –2.33 CS/100 and CiII = e –2.238 CS/100 generated good estimates for CiII, despite overestimating the subfactor in relation to the actual values recorded. The results also demonstrated that corn stover is effective at reducing interrill erosion.