Biomedical Engineering and Bioengineering Commons^™

Hydraulics Of Perforated Irrigation Trail Tube, John E. Gilley, Jan Feyen

Biological Systems Engineering: Papers and Publications

The author presented a methodology for calculating the hydraulics of trail tubes for center-pivot irrigation systems. While he mentioned several possible difficulties with trail tube irrigation, and stated that they have potential benefits in energy saving and improvements in water-use efficiency, additional clarification and analysis are required before the procedures he presented can be used for the rational design of such systems.
First and most importantly, a potential error in the analysis should be mentioned and discussed. The author used the two-term infiltration model of Philip to describe the water intake beneath a center-pivot irrigation system. The assumption of one-dimensional …

Soil Compaction I Where, How Bad, A Problem, Elbert C. Dickey, Thomas Peterson, Dean E. Eisenhauer, Paul J. Jasa

Biological Systems Engineering: Papers and Publications

Soil compaction is a more common problem now than it was 15 years ago, regardless of the tillage system used. Producers now use heavier tractors, larger implements, bigger combines, earlier spring tillage, reduced tillage, and no-till planting systems.

While all of these have a potential to increase compaction, the major cause of the problem is conducting field operations when the soil is too wet. Most think about tilling wet soils in the spring as being the major problem, but harvesting a too-wet field in the fall can cause just as much compaction. Large combines and auger wagons can have loads …

Interril Soil Erosion, Part I. Development Of Model Equations, John E. Gilley, D. A. Woolheiser, D, B. Mcwhorter

Biological Systems Engineering: Papers and Publications

Equations describing overland flow depth, rainfall induced soil detachment and sediment transport capacity on interrill areas were identified. The Darcy-Weisbach equation which included a parameter for predicting flow resistance caused by rainfall was used to calculate depth of overland flow. Soil detachment was determined from an equation incorporating raindrop induced, impact pressure estimates. The product of a soil transport factor, bottom shear stress and flow velocity was used to calculate sediment transport capacity. Nondimensional forms of the model equations were evaluated using existing experimental data.

Interril Soil Erosion, Part Ii. Testing And Use Of Model Equations, John E. Gilley, D. A. Woolhiser, D. B. Mcwhorter

Biological Systems Engineering: Papers and Publications

Laboratory measurements were made of interrill erosion as affected by varying overland flow discharge and slope slope steepness. Soil detachment and sediment transport capacity relations were then evaluated using experimentally obtained information.

The model equations were utilized to further characterize interrill soil erosion. The overland flow region over which the model equations are applicable for a disturbed Nunn clay loam soil was determined from laboratory tests and critical shear stress analyses. The influence of slope length on interrill erosion was also examined.

Estimating Crop Residue- Using Residue To Help Control Wind And Water Erosion, Elbert C. Dickey, John Havlin

Biological Systems Engineering: Papers and Publications

The Importance of Conservation Tillage

Conservation tillage has been practiced for many years and is becoming increasingly popular with Nebraska farmers. Recent surveys show, about 8 of 19 million cropland acres in Nebraska were farmed with conservation tillage systems. Conservation tillage includes a variety of tillage and planting systems that leave at least 30 percent of the previous crop's residue on the soil surface after planting.

Knowing how to measure or estimate residue cover is an important facet of conservation tillage. A minimum requirement of cover on the soil surface is often specified for U.S. Department of Agriculture programs and …

Soil Erosion From Tillage Systems Used In Soybean And Corn Residues, Elbert C. Dickey, David P. Shelton, Paul J. Jasa, Thomas Peterson

Biological Systems Engineering: Papers and Publications

Rainfall simulation techniques were used to compare soil losses from various tillage systems used on plots where corn and soybeans had been grown the previous season. The two year study was conducted on a silty clay loam soil with a 5% slope and on a silt loam soil with a 10% slope. Five tillage treatments, ranging from a moldboard plow system to no-till, were evaluated for each residue at each site. Tillage and planting operations were conducted up-and-down hill on replicated plots. Total soil loss following 63.5 mm of rainfall applied during a 60 min period averaged more than 40% …