CALIFORNIA AGRICULTURAL EXTENSION SERVICE Circular 140 September, 1947 LIQUID MANURE PUMPS AND EQUIPMENT John B. Dobie hm.: THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA • BERKELEY THE LIQUID-MANURE SYSTEM Prevents waste in the handling of animal fertilizer. Heavy losses occur when the natural liquid manure is not saved and when solid manure is subjected to dehydration and leaching before being applied to the land. Liquid manure has a more rapid effect on plant growth than has solid manure. Includes the barn and barn gutter, the transport gutters, storage tank, manure pump, power unit, and disposal equipment. It may be installed in any barn which has gutters to carry away the manure and the wash water. Pays for itself in one to three years. It operates at a cost of 6 to 9 cents per hour. Solves a serious problem in agriculture and an equally serious one in sanitation. This publication is the eighteenth in a series reporting results of investigations con- ducted by the California Agricultural Experiment Station in cooperation with the California Committee on the Relation of Electricity to Agriculture. LIQUID-MANURE PUMPS AND EQUIPMENT JOHN B. DOBIE 1 The loss in animal fertilizer through poor handling has long been considered a very serious problem by agriculturists. The value of these fertilizing ma- terials, based on prewar figures, is almost $30.00 per cow per year. This con- stitutes approximately 70 per cent of the fertilizer value removed from the soil per cow. Waste of so valuable a by-product should be avoided. In fact, a farmer is justified in spending a considerable amount for equipment so that he may return as much of the fertilizer to the soil as is possible. When a dairy operator saves only the solids of manure, and piles them aside for removal later to the fields, they are subjected to three sources of waste: First, the natural liquid manure usually drains out and is washed DISTRIBUTION SYSTEM^ _ f?77I77///W/ & MANURE PILE- PUMP TANK PREVAILING WIND NOT LESS THAN 50' CONCRETE CORRAL BARN GUTTER 777^//////////77/?7777/7/7///////r fTTTTA P^/ ///l - CON NEC TING GUTTER ^777777777177'' Fig. 1.— Profile sketch of liquid-manure system. through the gutters of the barn into a drain. This not only is a waste of fertilizer but is also unsanitary. Second, where only the solids are collected, some residue remains and it, too, is washed out, with the water used in cleaning the barn. Third, while the pile is accumulating in the barnyard, it is exposed to sun and rain; much of the soil nutrient material is lost through drying and fermenting and through leaching into nonproductive ground. Recognizing the losses inherent in the old methods of handling manure, the Agricultural Extension Office at Eureka, Humboldt County, in 1932, initiated a study of liquid-manure systems. They now have studied forty-three install- ations. Results of the work done have been applied to advantage in many other areas. The study has definitely proved that the liquid-manure method is an efficient means of recovery. It eliminates almost all of the traditional losses, because it saves the barn wash water, in which most of the solids col- lected from the barn are suspended. The system described in this circular, and pictured in figure 1, includes the barn and barn gutter, the transport gutters, storage tank (or pit), manure 1 Associate in Agricultural Engineering in the Experiment Station. [3 4 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 140 pump, power unit, and disposal equipment. This system may be used in any barn which has gutters to carry away the manure and wash water. THE BARN GUTTER drains into the transport gutters, \ which carry the liquids down the slope from the \ barn to the storage tank. These gutters must be J planned first. / The storage tank should be located at a lower elevation than the barn and in an out-of-the-way place where the prevailing winds will not carry objection- able odors to the milkhouse or the residence, when the tank is being emptied. On the dairy farm, the tank must be at least 50 feet from the milking barn and 100 feet from the milkhouse. Its elevation should be low enough so that barn gutters may be connected to it by transport gutters of sufficient slope to prevent settling out of solids in transit. A slope of 1 foot in every 10 feet is advisable, but usually is not possible in the contour of a barnyard. The tank should also collect drainage from the curbed concrete holding corral used for dairy cows. If the slope is much less than 1 foot in 10, heavy manure should be trans- ported to the tank by other means than gutters. If the heavy solids are to be handled separately from the liquid manure, they should be piled on a con- crete platform which is at least 50 feet away from the barn and 100 feet from the milkhouse. This concrete floor should be located so that any liquids formed on it will drain into the liquid-manure tank. In this way, leaching caused by rain will be collected in the storage tank. The manure pile must not be located in the loafing corral nor in any place where the cows have access to it. THE STORAGE TANK holds the liquid and solid ^\ manure, ft is usually constructed of concrete and is \ made watertight. Tanks vary in size, but most of J them are built to offer several days or weeks of / storage space. y The tank (or pit) collects the liquid manure and wash water for later dis- tribution to the field. The size of the tank varies greatly in present-day install- ations in California. Some small tanks are emptied one or more times a day; these are used primarily where liquid manure and barnyard waste present a sanitation problem. Most tanks provide for the accumulation of liquid and solid manure until there is sufficient quantity to permit good coverage of the area to be fertilized. LIQUID-MANURE PUMPS 5 Studies made by H. B. Walker of the Agricultural Experiment Station, Uni- versity of California, indicate that, where solids are removed by the dry method, an average of 1 1 gallons of water per cow per milking is used in washing the cows and barn. This average was developed from experimental data indicating a variation in the amount of water used by different operators of from 2 to 30 gallons per cow per milking. Individual practices may vary widely, but 1 1 gallons per cow per milking is a sufficient quantity for good practice. Total solids carried by these barn washings averaged 15,000 parts per million parts of water, including both organic and inorganic matter. The amount of water used for washing the barn may be greater where all solids are removed by flushing. If 11 gallons of water are used per cow per milking, or 22 gallons per cow per day when cows are milked twice daily, the storage tank should have a capacity of approximately 3 cubic feet per cow per day. Thus, a 40-cow dairy would require 40 x 3 = 120 cubic feet storage capacity per day. Assuming that the manure is accumulated for 30 days before it is applied to the field, a total capacity of 120 x 30 = 3,600 cubic feet is required. If the average depth of the tank is 6 feet, the area would then be 3,600/6 = 600 square feet. This tank would be 12 feet wide and 50 feet long. The lateral dimensions of the tank may be varied to fit the barnyard arrange- ment; therefore, no definite recommendations are made as to the shape of the unit. Square and rectangular tanks are equally satisfactory, if proper floor slope is furnished to the outlet point, although square tanks require less ma- terial for a given capacity. Round tanks are more difficult to cover satis- factorily. The depth of the tank is usually limited to about 8 feet, with 6 feet a good average, and the width should be 12 feet or less. Wider tanks are not recom- mended, unless additional support is provided for the tank cover. If a wider tank is needed, posts should be set in the floor of the tank, to support a joist running lengthwise down the center of the tank. Large tanks built above- ground should have crossties, to take part of the strain resulting from the pressure of the liquid. The following tabulation shows the suggested sizes of a liquid-manure tank, 6 feet in depth, for various-sized herds and for different periods of storage: Size of herd 1 day 5 days 15 days 30 days 10 cows 2' x4'* 3' x 9' 6' x 12 J /2' 10'xl5' 25 cows .... 4' x 5'* 6' x 10' 12' x 16' 12' x 32' 40 cows 4' x 8'* 10' x 10' 12'x25' 12' x 50' * 4 feet deep. In some dairies, it is preferable to run the waste water from the milkhouse into the barn gutters, through the transport gutters, and into the manure tank. Here again, the amount of water used varies widely, but averages about 2 cubic feet per cow per day. Where this practice is followed, additional capacity must 6 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 140 be provided in the storage tank. However, the addition of this water may dilute the manure more than is advisable; if so, some other method of disposal may be preferred. Recommendations for the slope of the tank bottom also vary with local practice. Where the tank is small and emptied often, a slope of 1 foot in 10 feet of length is not too much; this aids in keeping the tank clean without extra labor. For large-sized manure tanks, a slope of 1 foot in 50 feet is suffi- cient, but agitation of the liquid may be required to reduce settling of the solids and to obtain more complete removal at each pumping. Agitation may be provided by hand stirring, by recirculating part of the liquid passing Fig. 2.— Cutaway perspective drawing of a liquid-manure tank— or pit. through the pump, or by mechanical stirrers. Large rectangular tanks should have a shallow V-shaped floor, sloping to one end of the bottom of the V. The inlet to the manure tank should be at the top, and the outlet at the lowest point in the tank. For manure-pump installations, a sump is provided within the storage tank for the pump inlet. This facilitates complete removal of the manure and cleansing of the tank. The size of the sump will vary with the type of pump installed. In each case, it should allow ample space for entry of the material into the pump intake. The concrete sidewalls and floor of the tank should be not less than 6 inches thick, and should be reinforced throughout, with extra reinforcing at the corners. A 1:214:3 mix with 5 gallons of water per sack of cement is com- monly used. 2 Figure 2 shows a perspective drawing of a large liquid-manure tank. The storage tank should be completely covered and preferably flytight. The top of the sidewalls may be notched to take a 2-inch planking or a frame for an A-roof type cover. Planking is satisfactory where flies are not a problem, 2 Further information on proper concrete construction may be secured from the Portland Cement Information Bureau, 564 Market Street, San Francisco, California. LIQUID MANURE PUMPS 7 but it must be supported to withstand the heaviest load to which it may be subjected. A flytight cover is required in regions of high summer tempera- tures. This cover should be provided with a trapdoor for entry and sufficient clearance to permit servicing the pump and cleaning the tank. THE LIQUID-MANURE PUMP comes in two different types: the surface type, which is located near the edge of the tank; and the submerged type which is placed in the bottom of the tank. The rate at which the fertilizer is to be applied determines the size of the pump. The most popular size is the 3-inch pump delivering 175 to 450 gallons of water per minute, depending on the head against which it must operate. Although seldom used in sizes larger than a 3-inch discharge, some liquid- manure-type pumps are made as large as 8 inches. All manure pumps are of the centrifugal type, designed to handle a large amount of fine solid material without clogging. Some pumps are rated to handle up to 40 per cent solid material. Long straw or hay in the manure tends to clog these pumps, but such materials may be handled where reasonable care is exerted to hold down the concentration. Manure containing chopped hay is readily handled by all manure pumps. Surface-Type Pump. In this type the pump body is located near the edge of the tank, and a suction pipe with a foot valve is extended into the sump. A OUTLET u DRIVE 1/ " PULLEY SUMP Fig. 3.— Section of manure tank showing installation of surface-type pump, suction pipe, and foot valve. 8 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 140 discharge pipe is provided from the pump to the delivery point. This type of pump must be primed. Foreign materials in the foot valve may cause leakage, resulting in loss of prime and necessitating subsequent repriming. A hand valve is usually placed in the suction line near the pump to aid in holding the prime. This type of installation is shown in figure 3. DRIVE J^ OUTLET PUMP BODY Fig. 4.— Section of manure tank showing submerged type of pump. Submerged-Type Pump. This type is submerged at the bottom of the tank, and is driven by a long drive shaft which projects upward through a casing. The shaft runs in bearings in the shaft housing and is lubricated by a drip cup or zerk type of oiler. There is no suction pipe or foot valve on this pump, and the unit is self-priming. The discharge pipe is extended from the pump up over the side of the pit to the desired point of delivery. Such a pump is shown in figure 4. AN ELECTRIC MOTOR is the most satisfactory power \ to use in operating the pump/ if electricity is avail- \ able, because it is easy to start, is simple, compact, and does not need an attendant. It operates at a cost of 2 to 3 cents an hour per horsepower. ■j Manure pumps may be driven by electric motor, tractor, or gasoline engine. Where electricity is available, the electric motor is the most satisfactory. It is available in a satisfactory range of sizes and speeds for manure pump applica- tion. Since 3 horsepower is usually the maximum requirement for pumping liquid manure, any rural line will handle the load. The 3-inch pump requires a 2 to 3 horsepower electric motor. Either a single-phase or a three-phase electric motor can be used, but the three-phase is preferred. The pump manu- LIQUID MANURE PUMPS 9 facturer will indicate the size and speed of motor necessary for any given pump. The size of wire necessary to serve the installation will depend on the size of motor and the length of service line. Motor Controls. The electric motor should be protected by a good magnetic overload switch. This is especially desirable since foreign materials can get into the pump and severely overload the motor. For automatic control, a float switch may be used to start the motor, when the storage tank is filled to a certain point, and to turn it off when the tank is empty. CARE AND MAINTENANCE of the pump and the \ motor involve protection from the weather, clean- \ ing, lubricating, inspection and replacement of worn / or broken parts. J The elecric motor should be protected from the elements by some sort of cover or shelter. It must be kept properly lubricated, and should be cleaned occasionally. Where a single-phase motor is used, brushes should be in- spected periodically and replaced when worn out. The submerged type of pump requires only filling of the drip-cup oiler or lubrication with a grease gun. The pump which uses a suction pipe and foot valve is lubricated with grease cups; the foot valve may require some additional attention. Cast-iron pipe should be used for the suction or discharge, as wrought-iron is readily corroded by liquid manure. If wrought-iron pipelines are used, they should always be flushed thoroughly with water after contact with the liquid manure. APPLICATION OF LIQUID MANURE is made by two N, methods: the irrigation line, which carries it to the \ field in the irrigation water; and the tank wagon, j which transports if over rough terrain or where / irrigating is not done. / Irrigation-Line Method. Where application is made with the irrigation water, the liquid manure is usually pumped into the irrigation pipeline or head ditch, and is carried to the field by the irrigation water. If the irrigation system is piped, the liquid manure is usually admitted in the nearest stand- pipe. The standpipe should be located so that the liquid manure can be directed to any part of the farm. Where the manure is to be pumped through a piped irrigation system, the pipelines must slope sufficiently to insure against low spots where the fine solids could collect and eventually clog the system. Pipes should be smooth on the inside, as any irregularities tend to slow down 10 CALIFORNIA AGRICULTURAL EXTENSION CIRCULAR 140 the flow and causes settling of the solid particles. If the contents are to be pumped into an irrigation system which operates constantly, the pump may be made automatic. If the liquid manure is pumped through the pipelines when the irrigation water is turned off, care must be exercised to prevent clogging of the pipelines. Some operators start the irrigation pump each time the manure storage tank is pumped out. If this is not done, the liquid manure should have sufficient water added to cut down the concentration of solids and thus reduce the danger of clogging pipelines. Tank-Wagon Method. In areas of rough terrain or where irrigation is not practiced, the common method of distribution is with a water-tight tank wagon. This tank is usually a detachable rectangular wooden box which may be placed on any wagon- or truck-running gear. It is covered, with a trap door in the top for filling; the front is elevated about 6 inches so that the liquid manure will run out at the back. A spreader or splash plate is located below the unloading valve to spread the liquid the width of the wagon. A tank wagon of this type is shown on the cover of this circular. The wagon tank is filled at the storage tank, either by a liquid-manure pump or by gravity where the terrain permits. It is then driven to the field which is to be fertilized, and is unloaded as the wagon is driven over the field. This method insures direct application to the area where the fertilizer is needed. The unloading valve may be remotely controlled by the driver. The tank- wagon method of distribution is somewhat more adaptable than the irrigation method. It offers a relatively large storage space in which manure may be collected over a longer period and hauled away at the operator's convenience. LIQUID MANURE AS A FERTILIZER is more readily >, available to plants- than is solid manure, because A it is finely divided, and is held in suspension in the J water. It has a very rapid effect on plant growth. J I, ,,„' ", " M ''.I ■' \, I M M II W*^ Since manure pumps are usually intalled on dairy farms, it is natural that the liquid manure is ordinarily applied on pasture or forage cropland. The manure is very valuable as a fertilizer on this land. This has been shown in the increased yields where it was applied. Care must be taken in applying it during the growing season. Normally, it is not applied to a field less than 10 days before the field is to be pastured or the crop harvested. This is especially true on pasture land, because the livestock may refuse to graze for about 10 days after the application. This effect has also been noted in forage crops which have been harvested too soon after application, particularly where such a quantity of solids were deposited that they may be collected with the harvested crop. To irrigate after the application of liquid manure reduces this danger. LIQUID-MANURE PUMPS 11 Where the tank-wagon method of distribution is used, the fertilizer comes in direct contact with the plant, and may cause some burning. However, this is only a temporary condition. Where heavy concentration is desired on a given piece of ground, the application should be made just before plowing. Liquid manure works very well with a pasture-rotation plan. The manure application should be made as soon as livestock are taken off; then the pasture should be irrigated. By the time livestock are returned, all traces of objection- able odors or residue will have disappeared. Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. 10m-9,'47(A5033)