Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


The objectives of this study were to determine the effects on interrill erosion and runoff of: (1) various rates of surface straw, (2) various rates of incorporated straw, and (3) various rates of incorporated straw over two levels of surface straw. A randomized block design, a completely randomized block design and a 4 x 2 factorial using a randomized block design was used for objectives 1, 2 and 3, respectively. Grenada silt loam soil was placed in a 0.91 by 0.91-m soil pan with a central 0.46 by 0.46-m test area. The soil pan was on 2.5% slope. Simulated rainfall at 64 mm/hr was applied in a series of runs for each treatment. The series of runs consisted of an initial 60-minute "dry" run followed in 24 hours by two 30-minute runs ("wet" and "very wet" runs) separated by a 30-minute interval without rainfall. Increasing rates of surface straw from 0 to 8 t/ha resulted in decreased rates of soil loss, but caused little change in runoff. These was insufficient evidence to conclude that incorporated straw affected any changes in either soil loss or runoff for any level of surface straw. Incorporated straw had no effect on runoff or soil loss in this study because of the surface sealing of the Grenada silt loam soil. Research was limited to the interrill component of the erosion process. Future research should include studies on the effects of incorporated straw on rill erosion.