Jessica DavisColorado State University

Robert FlynnNew Mexico State University

Richard KoenigUtah State University

Reviewed December 2010

1

Table of Contents

THE NEED FOR A REGIONAL GUIDE

DAIRY SITE ASSESSMENT

CALCULATING LAND BASE REQUIREMENTS FOR

MANURE

LAND BASE REQUIREMENT WORKSHEET

NUTRIENT CONTENT OF COMMON CROPS

MANURE COLLECTION AND TREATMENT

ADDING VALUE TO MANURE - COMPOSTING

MANURE AND WASTEWATER STORAGE

MANURE CHARACTERISTICS AND SAMPLING

CALCULATING MANURE APPLICATION RATES

MANURE APPLICATION RATE/RECORD-KEEPING

WORKSHEET

MANURE APPLICATION METHODS

EQUIPMENT CALIBRATION

Feeding to Reduce NutrientExcretion

Recent advances have been made infeed formulation to reduce nitrogen (N) andphosphorus (P) excretion without reducinganimal performance. The ideal protein conceptis a feeding method in which crude proteinlevels are reduced and amino acids aresupplemented in order to reduce N excretion.For reduction of P excretion, adding phytase tothe diet has been shown to increase Pavailability to hogs and chickens. Most of theresearch on nutritional approaches to reducingmanure nutrient excretion has been done onmonogastrics, but research is now in progresson cattle feeding methods for this purpose.

A National Strategy for AnimalFeeding Operations

In March 1999 the U.S. EnvironmentalProtection Agency and U.S. Department ofAgriculture completed a joint national strategyfor the management of manure and wastewaterfrom animal feeding operations. The strategyinitially divides animal feeding operations intotwo categories: concentrated animal feedingoperations (CAFOs, operations with asignificant potential for causing environmentalpollution) and animal feeding operations(AFOs, operations with less potential forcausing environmental pollution). CAFOs willhave to obtain a pollution discharge permitand develop a comprehensive nutrientmanagement plan (CNMP) detailing howmanure and wastewater will be handled,stored and used. AFOs are also asked tovoluntarily develop a CNMP. The foundationof a CNMP is the adoption of best manage-ment practices for manure and wastewaterhandling, and the determination of applicationrates that properly meet crop nutrient needs

Best Management PracticesBest management practices (BMPs)

recommended are structural, vegetative, ormanagement practices designed to prevent orreduce water pollution. Implicit within theBMP concept is a voluntary, site-specificapproach to solving water quality problems.BMPs are both environmentally andeconomically beneficial.

2

The Need for a Regional Guide

Many manure management guides andregulations are based on the acidic soils andhigh precipitation climatic patterns common tothe mid-West and eastern United States.Western climates and soils are very differentfrom eastern conditions and warrant BMPstailored to these conditions in order tomaximize the beneficial reuse of manure whileminimizing the pollution potential.

Western agriculture has always hadmanure to utilize for crop production, but notin the quantities that are currently produced.Colorado, New Mexico, and Utah are home tomany livestock producers who use confinedfeeding operations. Furthermore, intensivelivestock feeding operations are oftenconcentrated along narrow river corridorswhere many of the region’s crops areproduced. Consequently, several thousandtons of manure are generated in a small area,and disposal quickly becomes an issue.Couple manure quantity with the economics ofmoving it to sites where it can be used, and adilemma develops which creates debate aswell as opportunity. Much of the debatesurrounds the disposal of manure, whileopportunities for enhanced crop production,production of value-added commodities likecomposts, and improved soil quality are oftenoverlooked.

How is the West different?Soils

Alkaline soils receive the majority ofthe manure applied in the West. The alkalinesoil environment and free calcium carbonate(lime) content of western soils will rendercertain nutrients unavailable to plants.Additionally, saline and sodic soils commonin this region require special managementconsiderations. Therefore, manure applicationrates may need to be adjusted for western soilconditions. For example, the salinity content

of the manure may limit applications to ratesless than those required to meet the nutrientneeds of plants.

ClimateYearly evaporation exceeds yearly

rainfall for most production agricultureregions in Colorado, Utah and New Mexico.Irrigation is used to supplement crop waterrequirements, and proper irrigation watermanagement must be practiced together withmanure management to minimize nutrientlosses.

The West also has intense storms thatcan cause movement of soil and nutrientsaway from the field of intended use. Thesesummer, monsoon-type storms may increasepollution potential if precautions are not takento reduce soil erosion and surface runoff.

Climatic differences also result inwestern manure stockpiles which are oftenlower in moisture content than easternmanures. Other manure characteristics, such asammonium content, also vary based on theclimate under which the material is stored.

Finally, western precipitation patternsare different from eastern states, which caninfluence the timing of manure applicationsand the amount of field runoff that occurs.

3

Dairy Site Assessment

Proper site selection can prevent manyof the problems related to dairy manure andwastewater control. Several factors in additionto land availability and cost should beconsidered when deciding where to locate anew facility. A site assessment for new andeven established facilities can aid in planningand design, improvements, and operation andmaintenance. The following guidelines aremeant to be a checklist of desirable attributesfor a dairy site location.

�Topographic featuresThe topography of the site is important

for runoff control and ease of facilitymaintenance (e.g., lot scraping). Consider thefollowing topographical characteristics:� Slope 3 to 5% to facilitate lot drainage.� Slope direction away from buildings and

water sources.� West or south facing aspect to increase

evaporation rates.� Location above the 100-year flood plain.

�Soil featuresSoil features such as texture and depth

to water table are important considerations forsiting dairy facilities. It is not possible tovisually evaluate all important soil features. Cooperative Extension Service or NRCSpersonnel can assist with soil evaluations.Also, soil surveys (published for most areas)contain information such as soil texture, depthto water table, and special limitations of soilsfor various uses.

Building site and lot areas� Medium texture, low shrink-swell potential.� More than 50 feet to a water table.

Storage ponds, lagoons, and stockpiles� High clay soils with low permeability.

Land application site� Relatively deep (3 or more feet), level,

productive soils.� Medium texture and moderate permeability

and drainage.

�Water quality and quantity� Good groundwater quality and quantity for

livestock and crop production.� Facilities located 150 feet from wells and at

least 1/4 mile from surface waters.

�Land application site� Sufficient land base for manure use (see pp.

5-6), or adequate neighboring farmlandto utilize manure.

� Reasonable transport distance for manureand wastewater.

� Minimum of 100 feet from wells andsurface water sources.

�Other factors to consider� Utility, labor, and market access.� Urban growth potential of the area and

future compatible land uses.� Visual barriers between the facility and the

public view.

4

Calculating Land Base Requirements for Manure

As dairies increase herd size, theyoften do not increase acreage. Therefore, agrowing dairy may have to buy feed fromother sources and may not have an adequateland base for manure utilization. Applyingincreasing quantities of manure to the sameland area may result in water quality problems.It is of critical importance that every livestockproducer know whether their land base isadequate for manure utilization.

If the land base is determined to beinadequate, arrangements must be made toreduce manure production (reduce herd size)or find alternative outlets for manure.Neighbors may own land with poor soils;manure could improve the productivity ofthese soils. There may also be opportunities tocompost manure and sell it to area gardenersand landscapers.

Gathering informationIn order to calculate the minimum land

base required, you will need the followinginformation:� Number of lactating cows, dry cows,

heifers, and other animals (e.g., beefcows).

� Average weight of lactating cows, dry cows,heifers, and other animals.

� Crop type which receives most of themanure.

� N removal by the crop (lbs/acre).� P2O5 removal by the crop (lbs/acre).

Use conservative estimates of annualcrop nutrient removal, and assume that all Nand P in the manure is available to the crop.This assumption is appropriate for long termsustainable manure use. Once you have thisinformation, complete the worksheet on thefollowing page to determine the land baserequirement for your dairy.

Using this worksheetThis calculation only has to be done

once unless you decide to expand your herd,buy additional acreage, or change croppingsystems.

Fill in your herd information includingnumbers and weight of each type of cow.Multiply the number of cows in each categoryby the average weight. Then multiply theresult by the nutrient production values shownin the worksheet. In the first section you willcalculate the total annual nitrogen (N)excretion by your herd, and in the secondsection you will calculate the total annualphosphorus (P2O5) excretion. This approach isconservative to ensure that your dairy has anadequate land base for manure application.

In the third section, you will need toknow how much nitrogen and phosphorus areremoved by an average yielding crop in yourarea. Use the table on page 7 or see yourcounty Extension or NRCS office for localinformation. Divide the excretion valuescalculated in the first two sections by the cropremoval. The answer is how many acres ofthat crop you need to utilize the manurenutrients.

In the West, manure applications areusually based on crop Nneeds. However, if soil testphosphorus (P) levels arehigh to very high andrunoff into nearby streamsis a problem, then basemanure applications on P.Note that the land baserequirement is considerablyhigher when it is P-basedthan when it is N-based.

5

Average Table values Nitrogen Excretion weight (lbs) (lb N/yr/lb cow) (lb N/yr)

Number of lactating cows: x x 0.164 = ______________Number of dry cows: x x 0.131 = ______________Number of heifers: x x 0.113 = ______________Number of beef cows: x x 0.109 = ______________

TOTAL =

Average Table values Phosphorus Excretionweight (lbs) (lb P2O5/yr/lb cow) (lb P2O5/yr)

Number of lactating cows: x x 0.059 = ______________Number of dry cows: x x 0.042 = ______________Number of heifers: x x 0.033 = ______________Number of beef cows: x x 0.084 = ______________

TOTAL =

N�based Land Base � Total N excretion (lbs/year)N removal (lbs/acre)

� acres

P�based Land Base �Total P2O5 excretion (lbs/year)

P2O5 removal (lbs/acre)� acres

Crop receiving manure: Yield goal:

N removal by crop: lbs N/acre

P removal by crop: lbs P2O5/acre

Land Base Requirement Worksheet

Herd information

Field information

6

Nutrient Removal by Crops Commonly Grown by DairyProducers in Colorado, Utah and

New Mexico†Crop lb N lb P2O5

Alfalfa Hay 56 per ton 15 per ton

Alfalfa Haylage 45 per ton 10 per ton

Grass Hay 40 per ton 13 per ton

Corn Silage (35% dry matter) 22 per ton 11 per ton

Oat Haylage (40% dry matter) 32 per ton 13 per ton

Wheat Haylage (30% dry matter) 50 per ton 13 per ton

Forage Sorghum (30% dry matter) 29 per ton 9 per ton

Sorghum Sudangrass (50% dry matter) 27 per ton 7 per ton

Barley Grain 1.4 per bushel 0.55 per bushel

Corn Grain 0.9 per bushel 0.37 per bushel

Wheat grain 1.7 per bushel 0.85 per bushel

†Check with state Extension or NRCS personnel for appropriate crops, expected yield,water requirements, and nutritional value when developing nutrient budgets. The tableabove serves as an initial estimate of nutrient removal by these crops.

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Manure Collection and Treatment

�Collection BMPs� Collect manure from pens as frequently as

possible to achieve optimum animalhealth and to comply with regulations.

� Maintain a firm, dry corral surface with theloose manure layer less than 1 inchdeep and 25-35% pen moisturecontent.

� Clean corrals to provide a smooth pensurface with 3-5% slope and maintainthe integrity of the hardpan below thecorral surface.

� Collect runoff from corrals, and divert otherrunoff water from pen areas.

�Dust, fly, and odor control BMPs� Harrow pens frequently to expose manure

and accelerate drying.� Sprinkle the corrals in dry weather to reduce

dust problems.� Change stocking density, if possible, to

control moisture content of the corralsurface and reduce odor and dustproblems when weather conditionswarrant.

� Use windbreaks to reduce dust and odorproblems.

� Communicate with neighbors to ensure theyunderstand the dairy operation and arenot harboring complaints.

Treatment optionsSolid separation is a treatment for

wastewaters from milking parlors. Settlingbasins or mechanical separators are used toremove solids from the wastewater resulting inreduced odor and less solids loading intolagoons. This treatment requires someinvestment in equipment and maintenance, butimproves the ease of liquid storage andhandling.

Lagoons are earthen structuresdesigned to treat manure by bacterialdegradation. Not every storage structurefunctions as a lagoon. Properly functioninglagoons reduce the solid and nitrogen contentsof liquid manure. In order to achieve thesetreatment goals, minimum depths of 6 ft foranaerobic and 3-5 ft for aerobic lagoons, aswell as a pH above 6.5, must be maintained sothat bacteria thrive and odors are controlled.

Aeration of wastewater storagestructures increases the oxygen level andreduces odors and solids. Aeration can beachieved through mechanical means orthrough gas exchange with the air in large,shallow ponds. The disadvantages ofmechanical aeration include high energy andmaintenance costs.

Anaerobic digestion is anothertreatment option in which manure is digestedto produce energy for farm use or possibly forsale to a local power company. This treatmentrequires a large start-up investment and highmaintenance, but also reduces manure odorsbecause the treatment vessel is enclosed.

Constructed wetlands can be a usefuloption because of high nutrient uptake bywetland plants and denitrification whichtransforms nitrate into gaseous nitrogen forms.The disadvantages include construction costs,the need for solid settling prior to treatment,and possibly increased biological oxygendemand of the treated water.

8

Adding Value to Manure—Composting

Why compost?� Volume reduction of 20 to 40% depending

on the method of aeration.� Nitrogen reduction by up to 50% due to

ammonia volatilization.� Uniform particle size product which is

easier to spread and is more acceptablein landscape and garden markets.

� Can assist in carcass disposal when the costof rendering becomes prohibitive.

Things to consider� Do not compost within 300 yards of a

residential neighborhood.� Aerobic, active turning of the manure will

increase volume reduction but increaseodors during the first week ofcomposting.

� Extra management is required (frequentaerating and moisture control) in thefirst four weeks of composting.

� Additional water is usually needed sincewestern manure stockpiles are oftenless than 60% water (the optimum forcomposting).

� Contractual services are becoming morecommon in many regions whereprivate enterprise will compost on-site.

Meeting expectationsIf you plan to give away, sell or market

compost, the material must meet buyer

expectations for particle size, and salt,nutrient, and moisture content. Manylandscaping companies and governmentagencies have specifications for compost.Check market requirements.

Weed control. Although weed seedscan be destroyed during composting, somedormant seeds survive the process. Controlweeds at the composting site and storage area.

Profitability? Composting is usuallynot a profitable enterprise for agricultural useof the product. Urban uses could provide ahigher value market. Evaluate the costs ofcomposting and transportation to marketsbefore adopting composting.

Composting mortalitiesWhole cows can effectively be

composted by burying the cow in a carbonsource such as sawdust or wheat straw. Laythe cow between two, 2-foot thick layers oforganic material. Turn every 2 to 3 months.The cow should be composted within oneyear.

Information resourcesComposting Education Resources of

Western Agriculture:www2.aste.usu.edu/compost/

Some compost recipes by percent volume Carbon source Manure Wood chips†none - 60% 40%

Cotton gin trash 45% 22% 33%

Small grain straw 25% 75% 0%

Sawdust 55% 45% 0%

†Add wood chips as a bulking agent to achieve aninitial bulk density of 700 to 1,000 lbs per cubic yard. Though not absolutely necessary, bulking the pile doesincrease temperatures. Adjustments should be made toachieve optimum performance.

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Manure and Wastewater Storage

�General BMPs� Locate manure stockpiles and wastewater

storage ponds at least 150 ft downstream from any well and above the100-year flood plain.

� Protect wellheads with grassed buffer areas.� Locate stockpiles and wastewater storage

ponds in slow permeability clay soilswith a deep watertable.

� Ensure adequate storage capacity to avoidwinter application.

�Stockpile BMPs� Use berms or trenches to keep stormwater

runoff away from stockpiles.� Use grassed filter strips below stockpiles to

reduce solids and nutrient contents inrunoff.

� Any potential runoff from stockpiles shouldbe collected in a lined or otherwiseimpermeable holding structure.

� Soil sample downhill from stockpiles tomonitor nitrate buildup in soil.

�Storage pond BMPs

� Remove solids from wastewater with asettling basin or separating screenbefore liquids are transported to the

storage pond. This will reduce odorsand extend the storage period.

� Seal storage ponds to prevent seepage.Liners can be made of compacted soil,bentonite clay, or heavy plastic.

� Ensure that the storage pond has thecapacity to handle runoff from a 25-year, 24-hour storm, in addition tonormal wastewater from the milkingparlor.

� Mark the top of the normal storage level inthe pond with adequate room abovethat for the 25-year, 24-hour storm. Ifthe pond level rises above the marker,the pond should be drawn down within15 days.

� Maintain at least 2 ft of freeboard in thepond at all times.

� Remove solids from the bottom of the pondwhen they exceed 8 inches in depth.

� Inspect your pond regularly. Maintainvegetated slopes, look for settling orbulges in the slopes, fill rodent holes,repair drying cracks, look for seepageoutside of embankments, and inspectinlet and outlet structures and valves.

� Keep cows away from storage pond banksto maintain the seal.

� Consider aerating or covering storage pondsor planting windbreaks if the odorbothers neighbors.

� When using ponds for either evaporationpurposes or storage prior to landapplication consider a second pond todivert runoff and allow for cleaningout the solids that collect in ponds.

� Store solids from separators so that drainagewater will collect in the storage pond.

� Have a contingency plan for wastewaterstorage or utilization in case of heavyrainfall.

10

Manure Characteristics and Sampling

Manure is a highly variable materialwhether in solid or liquid form. It is, therefore,critical that a representative sample be takento accurately determine manure nutrientcontent.

Sampling liquidsWhen sampling liquid manure or

wastewater, use a clean bucket and a plasticsample jar. There are several ways to sample:

�Sample from the storage ponddirectly with a water sampler. Walk or boataround the pond and collect a minimum of sixsub-samples. If possible, agitate the pond priorto sampling.

�Sample from a valve inserted in irri-gation line or directly from pond outlet pipe.

�Sample using cups placed in the fieldwhen manure is sprinkler irrigated.

Combine individual liquid sub-samples in a bucket and mix thoroughly.Transfer approximately one pint to a cleansample jar. Store the sample in a cooler orfreezer and immediately (within 24 hours)deliver to a lab. Some labs require samplepreservation for nitrogen and supply samplingbottles with the preservative.

Sampling solidsWhen sampling a solid manure

stockpile, remove the surface crust and use a

bucket auger or a sharpshooter (a narrowshovel) to core into the pile as deeply aspossible. Take samples from all sides of thepile, collecting a minimum of six sub-samples.Mix the sub-samples together in a cleanbucket and transfer about one pint to a heavy-duty, freezer-type plastic bag. Store the samplein a cooler or freezer and immediately (within24 hours) deliver to a lab.

Laboratory analysisHave the manure sample analyzed for

moisture content, pH, salts (electricalconductivity or EC), and N, P2O5, and K2Oconcentration. Check with the lab prior tosampling in case they have any specificrequirements.

Average valuesValues given in the table below are

average nutrient contents of dairy manures inColorado, Utah, and New Mexico. Thesevalues should be used with caution due to thelarge amount of farm-to-farm variability inmanure. Different feeding practices andmanagement techniques can have a significantimpact on manure nutrient concentrations andsalt contents. It’s best to take a sample fromyour own dairy following the procedureoutlined above.

Average nutrient contents of western dairy manures (fresh weight basis).

Solid Slurry Liquid

Moisture Content 46% 92% 99%

Electrical Conductivity 18 mmhos/cm 12 mmhos/cm 6 mmhos/cm

Total N 13 lbs/ton 24 lbs/1000 gal 4 lbs/1000 gal

P2O5 16 lbs/ton 18 lbs/ 1000 gal 4 lbs/ 1000 gal

K2O 34 lbs/ton 29 lbs/ 1000 gal 10 lbs/ 1000 gal

11

Calculating Manure Application Rates

Calculate the correct rate of manureapplication to prevent excess nitrogen (N) andphosphorus (P2O5) from accumulating in soiland contaminating ground and surface water.Various methods can be used to calculatemanure application rates. The worksheet onthe following page describes relatively simplemethods for calculating application ratesbased on N and P2O5.

Gathering informationIn order to calculate manure

application rates you will need the followinginformation:�The crop to be grown and expected yield.�Recent soil test results for each field.�An estimate of other nutrient credits.�A manure analysis for total N and P2O5.

Using this worksheetPhotocopy the worksheet as needed.

Complete one worksheet per field each yearmanure is applied. Keep the worksheets as arecord of the manure application history foreach field.

If soil test phosphorus (STP) levels arevery high (for example, greater than 100 ppmSTP by the Olsen or sodium bicarbonateextract method), apply manure on the basis ofP2O5 removal by the crop (second column onworksheet), or take measures to prevent runofffrom these high phosphorus fields.

1. Nutrient recommendations are basedon the crop to be grown and yield. Refer tosoil test reports, fertilizer guides, or your localExtension or NRCS office for nutrientrecommendations. If manure applications willbe made on the basis of P2O5, use crop P2O5

removal (see page 6) as the basis for thenutrient recommendation.

2. Nutrients from other sources(credits) may include residual nitrate-N fromsoil tests, supplemental fertilizers, N in

irrigation water or from previous legumecrops, or nutrients from previous manureapplications.

3. Supplemental nutrients needed is theamount of N or P2O5 supplied by the manure.

4. Total N or P2O5 in manure (on afresh weight basis) is based on a manureanalysis. If a manure analysis is not available,use average values given on page 11 for yourmanure form.

5. Nutrients are released over time asmanure decomposes in soil. The nutrientavailability factor is the fraction of total N orP2O5 in manure available in the year ofapplication. All of the P2O5 is assumed to beavailable in the year of manure application toprevent further phosphorus accumulation inhigh P-testing soils.

6. Available nutrients in manure is theamount of N or P2O5 available for plant use inthe year of manure application.

7. Manure application rate is rate ofmanure to apply to meet crop nutrient needs.

� Other factors to consider� Soil testing improves the accuracy of

manure rate calculations. Soil testannually on fields receiving manure.

� Monitor soil test nitrate and phosphorus androtate manure to other fields if levelsare approaching high values.

� Keep records.

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Field number or description: Number of acres: Crop: Yield goal: Soil test nitrate-N: lb N/ac or ppm* Soil test phosphorus: ppm*Crop nitrogen (N) recommendation: lb N/ac *ppm = parts per million.

Crop phosphorus (P2O5) removal (see page 6): lb P2O5/ac

Manure form: � Solid � Slurry � LiquidManure N content: lb/ton or lb/1000 gallonsManure P2O5 content: lb/ton or lb/1000 gallonsMethod of application: �Broadcast �Broadcast-incorporation �Injection

N-based P2O5-based1. Nutrient recommendations (lb/acre)

(soil test report or calculation)

2. Nutrients from other sources (credits) (lb/ac)

3. Supplemental nutrients needed (lb/ac)(subtract line 2 from line 1)

4. Total N or P2O5 in manure (lb/ton or lb/1000 gal) (from manure test or assumed value)

5. Nutrient availability factor (N-based: use 0.4 for solids, 0.3 for liquids or slurries, and 0.2 for composts; P-based: use 1.0)

6. Available nutrient in manure (lb/ton or lb/1000 gal)(multiply line 4 by line 5)

7. Manure application rate (tons/ac or 1000 gal/ac†)(divide line 3 by line 6) *

*Note: This worksheet assumes solid manure will be incorporated immediately. If manure will be incorporatedmore than one week after application, then multiply the N-based rate on line 7 by 1.4.

† There are 27,154 gallons per acre-inch and 325,851 gallons per acre-foot.

Manure Application Rate/Record-Keeping Worksheet

Field and soil information Year:

Manure information

Application rate worksheet

13

Manure Application Methods

The type of manure collection andstorage system, as well as transport distancesand cost, influence the choice of applicationmethods. The main factor governing the typeof application method used is manuremoisture content (see table below).

Types of manure and spreading equipment.

Manure form % Solids Equipment

Solid 35-80 Box spreaders

Semi-solids 10-35 Flailspreaders(slingers)

Liquid slurry 2-12 Tank wagons

Liquid manure 0-7 Big guns orgated pipe

Storage pondor lagoonwater

0-4Sprinklers*,big guns,gated pipe

*may require screening or chopping

Solid manureUsing tractor-drawn or truck-mounted

box units for spreading solid manure is astandard practice on many dairy farms.Consider the following points for solidspreading:� Water is heavy and expensive to haul even

short distances. Minimize the watercontent in manure by installing a solid-liquid separator, or drainage slats inthe solid manure storage structure.

� Solid manure spreaders come in varioussizes and configurations. Dump trucksdo a poor job of distributing manure.Spreaders with a hydraulic ram orwalking floor to push manure out therear of the unit facilitate more uniformspreading.

� Use larger capacity units for longertransport distances to minimize thenumber of trips required.

Semi-solids and slurries

Transport of semi-solid or slurry formsof manure should be limited to short distances.Consider drying the manure or adding water tohandle the material as a true solid or liquid.

LiquidsHandling manure as a liquid minimizes

the need for additional tractor-drivenimplements and offers the advantage of usingthe irrigation system already in place formanure transport and application. Consider thefollowing points for liquid manureapplication:� Open ditches, furrows, and basin irrigation

systems are not recommended forliquids due to poor uniformity ofapplication.

� Manure with less than 4% solids is pumpedas easily as water through normalirrigation systems.

� Run clean water through the system at theend of the irrigation cycle to flush the systemand wash manure off leaf surfaces.

14

Equipment Calibration

The value of carefully calculatingmanure application rates is seriouslydiminished if application equipment is notproperly calibrated.

Solid and slurry spreadersManure spreaders discharge at widely

varying rates, depending on travel speed, PTOspeed, gear box settings, discharge openings,and manure moisture and consistency.

Calibration requires measurement ofthe amount of manure applied on a given area.This can be accomplished on three scales:

� field scale (many spreader loads)� one spreader load� tarp size (< 1 spreader load)

The smaller the scale, the more potential forerror. Therefore, where possible use field scalecalibration.

Field scale calibration steps1. Determine the size of the area or

field where manure will be spread.2. Count the number of loads of

manure applied to the field. For solid manure,weigh at least three loads and calculate theaverage weight. For slurry manure, usevolume measurements instead of weight.Calculate the volume of a cylindrical tank bymeasuring the tank length, depth, and width infeet. Multiply length × depth × width × 0.8 toget cubic feet of slurry. Convert to gallons bymultiplying cubic feet by 7.48.

3. Multiply the number of loads by theaverage weight (or volume), and then divideby the field or area acreage. This gives theaverage application rate per acre. Adjust thespreader setting or ground speed as necessaryto achieve the desired application rate.

Other factors to considerCheck the calibration whenever a

different manure source with a new moisturecontent or density is applied. Using well-maintained equipment and proper overlapdistances will ensure better nutrientdistribution and help avoid “hot spots” orareas with nutrient deficiency.

Sprinkler systemsWhen liquid manure is applied through

sprinkler irrigation systems, it is essential thatmanure contain <4% solids, nozzles are largeenough to avoid clogging, and that nozzles arethe same size throughout the system to ensureuniform application (except for center pivots).

There are three methods for calibratingsprinkler systems for manure application:

1. Can test. Place 12 rain gauges orstraight-sided cans under sprinkler system.Measure the depth of liquid collected overtime.

2. Flow meter. Note the flow meterreading and the duration of application, anddivide by the area receiving the manure.

3. Depth measurement. Measure thechange in effluent depth in the pond andmultiply that by the area of the pond. Thendivide this volume by the area of landreceiving the application.

Meet the Authors

Jessica G. Davis, Ph.D.Department of Soil and Crop SciencesColorado State UniversityFort Collins, CO 80523-1170

Jessica is the Extension Soil Specialist for Colorado State UniversityCooperative Extension. Her research emphasizes using manure toimprove soil properties while protecting water quality, economically andenvironmentally sound fertilizer utilization, and diagnosis and restorationof “alkali” soils. She teaches a class in manure management. Jessica canbe reached at jgdavis@colostate.edu or by phone at 970-491-1913.

Richard T. Koenig, Ph.D.Department of Plants, Soils and BiometeorologyUtah State UniversityLogan, UT 84322-4820

Rich is a Soil Specialist for the Utah State University CooperativeExtension Service. He serves as the statewide specialist in soilfertility, nutrient management, and soil improvement. Rich can bereached at richk@ext.usu.edu or by phone at 435-797-2278.

Robert P. Flynn, Ph.D.New Mexico State UniversityAgricultural Science Center at Artesia67 E. Four Dinkus Rd.Artesia, NM 88210

Robert has a dual appointment with the NewMexico Cooperative Extension Service and theAgricultural Experiment Station. He serves asan extension agronomist with an emphasis in

soil management and conducts a research program in soil fertility. His program seeks to improvecropping systems that receive manure, and assist producers in achieving a productive andenvironmentally sound farming system. Robert can be reached at rflynn@nmsu.edu or by calling505-748-1228.

Utah State University is committed to providing an environment free from harassment and other forms of illegal discrimination based

on race, color, religion, sex, national origin, age (40 and older), disability, and veteran’s status. USU’s policy also prohibits discrimination on the basis of sexual orientation in employment and academic related practices and decisions. Utah State University employees and students cannot, because of race, color, religion, sex, national origin, age, disability, or veteran’s status, refuse to hire; discharge; promote; demote; terminate; discriminate in compensation; or discriminate regarding terms, privileges, or conditions of employment, against any person otherwise qualified. Employees and students also cannot discriminate in the classroom, residence halls, or in on/off campus, USU-sponsored events and activities.

This publication is issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Noelle E. Cockett, Vice President for Extension and Agriculture, Utah State University. AG/WM-04,1999