Ground Cover Estimates for Seedling Cereal Crops
1985
Rickman, R. W. | Rasmussen, Paul E.
Fields sown to winter cereals are often damaged by water erosion. Erosion can be reduced if sufficient green plant or crop residue cover is present over winter. The selection of a planting date that will provide adequate overwinter cover is critical to successful management. This manuscript explains how plant cover can be predicted for any date after planting of a winter cereal from historic air temperature records. Degree-days accumulated from planting are linearly related to cereal leaf development at 80 to 120 degree-days per leaf. The lengths of successive leaves provide the radii of successively larger circles which are used as the basic unit for computing field cover. A plant is assumed to uniformly shade the circular area surrounding it. The area of overlap of adjacent circles is assumed to be shaded by the sum of the shading from each circle. Formulas are provided to illustrate the effect of row spacing, seeding rate, leaf size, and plant development rate on the rate and pattern of formation of cover. Comparison of calculated and observed field cover from four different growing seasons demonstrated the need for correcting the calculations for mutual shading of leaves. When mutual shading by leaves of 1% per layer of overlap is used, calculated and observed percent field cover are not different. Historic air temperature records can be used with leaf length values characteristic of a cultivar and specific field management choices to provide the latest seeding date that will provide a desired amount of field cover.
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