Doctoral Dissertations

Date of Award

6-1973

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Biosystems Engineering

Major Professor

John T. Sewell

Committee Members

James T. Miles, Bruce A. Tschantz, John J. McDow

Abstract

Dairy and beef industries have recently undergone changes toward increasing sizes of livestock herds5 confined housing and feeding of animals^ and use of concrete lots and hydraulic cleaning for transport of animal wastes. Lot runoff containing heavy concentrations of animal wastes can result. This waste slurry must be managed by lagooning or spreading on the ground in such a manner that it can be utilized or degraded by plants and bacterial action while maintaining high soil and water quality« Irrigation of pastures and cropland with animal waste slurry appears to be a practical approach to the management problem for many areas and situations.

The major objectives of this study were to determine the effects of slurry irrigation on surface runoff and groundwater quality and to develop techniques for irrigating with dairy manure slurry.

An experimental manure slurry irrigation system at the University of Tennessee Knoxville Cherokee Dairy Farm served approximately one acre of concrete lot, loafing area, and building roofs at the dairy with about 125 milking cows where manure slurry, rainfall runoff, and wastewater were collected into drains and delivered by gravity flow into a 75,000- gallon concrete storage tank, A comercially available pumping system consisting of a 15-hp chopper-agitator unit and a 25-hp open-impeller centrifugal pump which delivered 200 gpm at 60 psi was installed at the storage tank. The slurry was delivered through 4-inch portable aluminum irrigation pipeline to a special "gun-type" manure slurry sprinkler with a 7/8-inch rubber nozzle which covered approximately one acre per setting.

A four-acre pasture plot with ground slopes varying from about 20 percent to almost flat was selected as a manure slurry saturation area to study the effects of the surface spreading of manure slurry on the quality of groundwater and surface runoff» Three groundwater wells extending approximately 50 feet below the ground surface were drilled in the vicinity of the saturation area for periodic collection of samples for analyses of the shallow groundwater table believed to be bounded underneath by an impervious layer of limestone. Grab samples of rainfall runoff from the surface of the manure-saturated plot were also collected and analyzed for total and fecal coliform bacteria, BOD, COD, nitrate and nitrite nitrogen, orthophosphate, chloride, and dissolved solids.

An average application of 5.55 tons dry matter per acre per month applied in the form of dairy manure slurry presented no problem of solids accumulation on the ground surface. During normal soil moisture conditions on pasture sod having moderate Infiltration capacity, an average sprinkler application rate of 0.5 inch per hour for periods of about three hours per sprinkler setting appeared to be a satisfactory application rate between minimum surface runoff and minimum operation time between sprinkler settings. Maintaining the dry matter content of the slurry in the 1 percent to 4 percent range gave good pumping system equipment performance.

Manure slurry apparently infiltrated into the shallow groundwater on the downgrade side of the manure-saturated area, A leak around the well casing was suspected since resealing of the ground surface around the casing and subsequent disinfection of the well resulted in decreasing bacterial and chemical concentrations. Except for isolated cases, samples from the groundwell on the downgrade side of the saturation area were within the permissible criteria for raw surface water for public supplies as set forth by the Federal Water Pollution Control Administration in 1968. The parameter concentrations of the surface runoff samples appeared to depend heavily on the location of the sampling points with reference to the source of the pollutants, volume of runoff and dilution of the pollutants, and the time during the runoff cycle at which the samples were taken.

The manure slurry irrigation system receiving manure solids, rainfall runoff, and wastewater has performed satisfactorily and has been durable. Optimum performance of the system requires careful management to continuously maintain storage capacity for lot runoff while controlling surface runoff of irrigated slurry. The slurry irrigation system offers, for some types of operations and situations, possibilities for improved efficiency in dairy manure management while creating a minimum of pollution problems.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS