Cover provided by crop residue is very important for controlling wind erosion. The Wind Erosion Prediction System (WEPS) includes a model for the decomposition of crop residue. It simulates the fall rate of standing residue and the decomposition of standing and flat residue as a function of temperature and moisture. It also calculates the fraction of soil covered by residue from flat residue mass. Anecdotal evidence suggests that the model may overestimate stem fall and decomposition, and underestimate cover, especially in the central and northern USA.

We will compare the WEPS simulated soil fraction covered by residue with that measured in south-central North Dakota for ten different crops: barley, canola, crambe, dry bean, dry pea, flax, safflower, soybean, spring wheat, and sunflower. The crops were grown under no-till conditions on a Wilton silt loam soil receiving on average about 400 mm of precipitation per year. Measured data include residue mass at the time of harvest and soil fraction covered by residue just after planting the next spring. Local weather data, needed to drive the WEPS decomposition submodel, are also available.

Comparison of measured with simulated residue cover will help to validate and possibly improve the WEPS decomposition submodel.

Keywords: residue cover, residue decomposition, wind erosion