Date of Award
Master of Science
Larry L. Bauer
Charles M. Cushaden, William Goble
A system of handling manure from the milking cows must be used on each and every dairy farm in Tennessee. The decision as to what means should be used cannot be made on a statewide or even countywide basis because there are too many variations in individual operations. Four systems are being used throughout the state to handle the major part of this manure. These are lagoons, liquid systems, conventional systems, and irrigation systems. Many farmers are finding that they need to change to another type system and would like to know what is involved in setting up a different system. Farmers starting new operations need information so that they can make logical decisions as to which system to use.
The general objective of this study was to compare the four systems so that operators would be informed on the various aspects of each system. Emphasis was put on costs involved with each system; other factors were also emphasized.
Costs involved with each system were determined from the estimated amount of equipment needed and man hours required to operate each system. Ten different herd sizes were included in order to get a range of situations. For the liquid system, six periods of holding time were considered for each of the 10 herd sizes since a decision has to be made in this system as to how many days are desired between hauling times.
An estimated value for manure from each cow each year was determined. Each system was compared as to expected returns per herd and per cow when manure is assumed to have this value. There are dairy farms that desire only to get rid of the manure. The costs involved in. each system when this is the objective were determined.
Many factors other than cost are involved in decisions as to which system to use. These factors are considered in the discussion and summary but are not a paft of the costs and returns. Dollar value was placed only on the plant nutrients in the manure.
Lagoons are the lowest cost operations and require the least man hours. They can only get rid of the manure, however, and show no positive net returns at any point. Each of the other systems have positive returns for some herd sizes when costs are compared to returns for spreading the manure. It is the least cost operation for all herd sizes when the only purpose is to get rid of the manure. Some farms will not have suitable locations to use lagoons.
Liquid systems have a wide range of expected returns when costs are compared to the value of the manure. The larger herds can expect positive returns unless they desire to have long periods between times of emptying the pit. The system has some advantage in that it takes little surface room and allows the operator to determine how often he will haul the manure. It has disadvantage in that it requires large sums of money for pits and equipment.
Conventional systems require the least amount of money of the three systems which allow the manure to be returned to the soil. Net returns for the system are generally higher than for the other systems. The operator has little choice of hauling times and this can tie up labor and equipment when it is needed elsewhere.
Irrigation systems require the least amount of money of the three systems which allow the manure to be returned to the soil. Net returns for the system are generally higher than for the other systems. The operator has little choice of hauling times and this can tie up labor and equipment when it is needed elsewhere.
Irrigation systems are being used more than in the past because more water is handled through many dairy operations. The system gives greater net return than does the liquid system when long holding periods are desired for liquid systems. Large sums of money are tied up in equipment and small size herds show large net losses when using irrigation systems. It takes very little surface area for the holding pit and provides a good way for removing excess water along with the manure.
Each of the systems may be observed throughout the state. Some operators have personal reasons for wanting to use the higher cost systems even where the possibility exists for using any of the four. An informed decision as to which system to use can be made from results of this study.
Henderson, Harry A., "Comparisons of manure disposal systems being used on Tennessee dairy farms. " Master's Thesis, University of Tennessee, 1972.