Booklet 3

Managing Livestock Manures

Booklet 1 Making better use of livestock manures on arable land

Booklet 2 Making better use of livestock manures on grassland

Booklet 3 Spreading systems for slurries and solid manures

Copies available from:

ADAS Brian Chambers, Nick Nicholson and Ken SmithInstitute of Grassland and Environmental Research Brian PainSilsoe Research Institute Trevor Cumby and Ian Scotford

Written by

ADAS Gleadthorpe Research CentreMeden ValeMansfieldNottsNG20 9PF

Telephone: 01623 844331Fax: 01623 844472Email: glyn.scrimshire@adas.co.uk

Spreading systems for slurries and solid manures

S I L S O E R E S E A RC H I N S T I T U T E

Funded by the Ministry of Agriculture, Fisheries and Food

2001

Slurries and solid manures are valuable fertilisers but may also be potentialsources of pollution. With increasing economic and environmental pressureson farm businesses, it makes sense to exploit the fertiliser value of manures,while taking action to prevent pollution.

The booklets in this series will assist in achieving these aims by providing practical advice so that you can:

• save on the cost of inorganic fertiliser• operate machinery effectively

• minimise management problems• comply with the MAFF Codes of Good Agricultural Practice.

The booklets have been produced jointly by IGER, ADAS and SRI and areavailable free of charge. The information they contain is based largely onresearch conducted by these three organisations over the past ten years,much of which was paid for by MAFF.

This booklet explains how to:• select the right spreading system

• prepare for field spreading• organise slurry and manure sampling

• calibrate spreaders.

Handling of slurries and solid manures createscertain safety hazards for both operators and thepublic. You must comply with relevant legislation.Key sources of information are listed on page 17.

In this booklet, manures refer to organic materials which supply organic matter to

the soil, together with plant available nutrients (in relatively small concentrations

compared to inorganic fertilisers). They may be either slurries or solid manures.

Slurries consist of excreta produced by livestock in a yard or building mixed with

rainwater and wash water and, in some cases, waste bedding and feed. Slurries can

be pumped or discharged by gravity.

Solid manures include farmyard manure (FYM) and comprise material from covered

straw yards, excreta with a lot of straw in it, or solids from mechanical slurry separators.

Most poultry systems produce solid manure. Solid manures can generally be stacked.

Why read this booklet?

01

02 Why controlled application is important

02 Understanding nutrient losses

02 Slurry: selecting the right handling and spreadingsystem

06 Solid manure: selecting the right spreader

09 Preparing for spreadingManagement of stored manures

Protecting the environment

Timing of application

11 Sampling slurry and solid manure for analysisWhy correct sampling is important

General principles of sampling

Sample analysis

13 Calibrating and operating spreadersApplication rate

How to estimate/measure application rate

17 How to obtain more information

18 Conversion table

Contents

Booklet 3

• Pumped tanker – the slurry is pumped into and from the tanker using a

slurry pump, either a centrifugal (e.g. impeller type) or positive displacement

(e.g. lobe type) pump.

• Umbilical hose – the slurry is fed by a drag hose to the distribution system

fitted to the tractor; the hose is supplied with slurry usually direct from the

slurry store by a centrifugal or positive displacement pump.

• Irrigator – this is a self-travelling machine with flexible or reeled-in hoses

usually fed from a network of underground pipes, with a centrifugal or positive

displacement pump, situated near the slurry store.

Table 1 Slurry transport systems

Vacuum Pumped Umbilical Irrigatortanker tanker hose

Range of up to 12% up to 12% up to 8% up to 3%dry matter

Requires No No (centrifugal) No (centrifugal) Yesseparation Yes (PD pump) Yes (PD pump)or chopping

Work rate ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ (depends on field size/shape)

Accuracy of ✓ ✓ ✓ (centrifugal) ✓ ✓ (centrifugal) ✓ ✓application rate ✓ ✓ ✓ (PD pump) ✓ ✓ ✓ (PD pump)

Soil compaction

Capital costs £ £ (centrifugal) £ £ £ £ ££ £ (PD pump)

Labour requirement per m3

Comments Versatile – can be Generally better Possible crop damage Suitable for semi-used for most slurry spreading precision as hose drags across automatic operation, transport jobs than vacuum tankers. ground, hose damage but anti-pollution

More maintenance and wear can be a safeguards needed required for problem on abrasive (e.g. pressure + PD pumps or flinty ground flow switches)

Note: PD = positive displacement

03

Why controlled application is important

To ensure that the intended amount of nutrients in slurry and solid manure

has been applied to the crop, it is important that the machinery used is chosen,

calibrated and operated to give accurate application. This means that it should

be capable of being set up to apply the intended rate in m3/ha or tonnes/ha,

and to produce an acceptably even spread pattern.

Coefficient of variation (C of V) is a measure of the uniformity of spread

achieved, both laterally and longitudinally. A high number indicates a poor

uniformity. With granular fertiliser, a C of V of less than 15% is normally

considered acceptable. Research suggests that slurry tankers and manure

spreaders should be chosen and operated to give a C of V of less than 25%. Using

an appropriate bout width is critical in achieving a reasonably uniform spread.

Understanding nutrient losses

Gaseous emissions from land application of slurries and solid manures account

for a large proportion of the total ammonia emissions from agriculture. It is very

important to minimise losses at this stage because any ammonia saved during

livestock housing or manure storage will be lost if it is not controlled by appropriate

field application techniques. Reducing ammonia losses from slurries and solid

manures means more nitrogen is potentially available for grass and crop uptake.

Slurry: selecting the right handling and spreadingsystem

There are four main types of slurry transport systems (see Table 1).

• Vacuum tanker – the slurry is sucked into the tanker by using an air pump to

evacuate the air from the tank to create a vacuum; the tanker is emptied using

the air pump to pressurise the tanker, so forcing the slurry out.

02

05

There are four main types of slurry distribution systems. (See Table 2.) Each can

be fitted onto a vacuum tanker, pumped tanker or used with an umbilical system.

Self-travelling irrigators cannot be used with injectors.

• Broadcast spreader (splash plate or nozzles) – the slurry is forced under

pressure through a nozzle, often onto an inclined plate to increase the

sideways spread (see Figure1).

Figure 1 Vacuum tanker fitted with splash plate

• Band spreader – the boom of the spreader has a number of hoses connected

to it, distributing the slurry close to the ground in strips or bands. It is fed with

slurry from a single pipe, thus relying on the pressure at each of the hose

outlets to provide even distribution. Advanced systems use rotary distributors

to proportion the slurry evenly to each outlet (see Figure 2).

• Trailing shoe spreader – this is a similar configuration to the bandspreader

with a shoe added to each hose allowing the slurry to be deposited under the

crop canopy onto the soil (see Figure 3).

• Injector – slurry is injected under the soil surface. There are various types

of injector but each fits into one of two categories: either open slot shallow

injection, up to 50 mm deep; or deep injection over 150 mm deep (see Figure 4).

04

Slurry is placedin shallowopen slots

Slurry is placedunder the cropcanopy

Figure 2 Band spreader fitted with rotary

distributor to improve lateral distribution

Figure 4 Open slot shallow injector

Slurry is placedin narrowbands

Figure 3 Trailing shoe spreader

07

Table 2 Slurry distribution systems

Broadcast Band Trailing Shallow Deepspreader spreader shoe injector injector

Typical range of up to 12% up to 9% up to 6% up to 6% up to 6%dry matter

Requires separation No up to 6% No Yes Yes Yesor chopping over 6% Yes

Relative work rate ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜

Uniformity across ✓ ✓ (simple) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓spread width ✓ ✓ ✓ (advanced)

Ease of bout ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓matching

Crop damage

Relative level ofodours and ammoniaemissions

Capital costs £ £ £ £ £ £ £ £ £ £ £ £ £

Solid manure: selecting the right spreader

Three main types of solid manure spreaders are commonly used.

• ‘Rotaspreader’ – a side discharge spreader which features a cylindrical

body and a pto-driven shaft fitted with flails running along the centre of

the cylinder. As the rotor spins, the flails throw the solid manure out to

the side (see Figure 5).

• Rear discharge spreader – a trailer body fitted with a moving floor or

other mechanism which delivers solid manure to the rear of the spreader.

The spreading mechanism can have either vertical or horizontal beaters,

plus in some cases spinning discs (see Figure 6).

• ‘Dual purpose spreader’ – a side discharge spreader with an open top

V-shaped body capable of handling both slurry and solid manure. A fast

spinning impeller or rotor, usually at the front of the spreader, throws the

material from the side of the machine. The rotor is fed with material by an

06

auger or other mechanism fitted in the base of the spreader and a sliding gate

controls the flow rate of the material onto the rotor (see Figure 7).

Table 3 compares the relative performance of the three types of solid manure

spreader.

Table 3 Solid manure spreaders

‘Rotaspreader’ Rear discharge ‘Dual purpose spreader’or open side spreader or side impellerdischarge spreader discharge spreader

Suitable for No (a) No (a) Yesslurry

Work rate ➜ ➜ ➜ ➜ ➜ ➜ ➜ ➜

Accuracy of ✓ ✓ ✓ ✓ ✓ ✓discharge rate

Lateral precision ✓ ✓ ✓ ✓ ✓ ✓

Ease of bout ✓ ✓ ✓ ✓ ✓ ✓matching

Soil compaction

Relative costs £ £ £ £ £ £

Notes

(a) Some of these machines can be fitted with slurry guards or gates but they are usuallypurchased for spreading solid manure.

09

Preparing for spreading

The MAFF Codes of Good Agricultural Practice for the Protection of Water, Air and

Soil provide guidance on avoiding water pollution, soil contamination, odours and

ammonia losses.

Draw up a farm waste management plan to help you decide when, where and

at what rate to spread slurry and solid manure on your farm. You can get further

information on farm waste management plans by reading the Water Code,

obtaining the MAFF step-by-step guide or contacting a consultant on the National

Farm Waste Management Plan Register (see page 17).

Management of stored manures: even the most efficient systems for handling

and spreading manures will fail if they are not carefully matched to storage and

treatment systems. To make the most of your spreading system, the following

points should be considered.

• Don’t allow loose concrete, bricks, wire, timber, etc. to get into reception pits

or stores; they may damage machinery and can be a safety hazard.

• If the handling system is designed to work only with slurry, exclude waste

bedding and feed from reception pits and stores to avoid blockages.

• Mechanical separation of slurry removes coarse solids, enabling the slurry to

be pumped more easily. Separated slurry does not crust or settle in the store

and so requires less mixing.

• If mixing is required, it is advisable to begin mixing the contents of slurry

stores a few days before emptying. Mixing enables complete emptying of

the store and removes the crust from the slurry surface, as well as producing

a more uniform slurry for spreading.

• Completely empty slurry stores at least once a year, especially if there is a

crust or if sediment has accumulated.

Protecting the environment: Wherever possible, use a band spreader, trailing

shoe spreader or injector to apply slurry. Where this is not possible, use a broadcast

slurry spreader that gives a low trajectory and large droplets. After surface

application of slurry or solid manure to bare land, incorporate the material into

the soil within twenty-four hours of spreading and, where practical, within four

08

Figure 5 Rotaspreader

Figure 6 Rear discharge spreader

Figure 7 Dual purpose spreader

11

Sampling slurry and solid manure for analysis

Why correct sampling is important: the nutrient content of slurry can vary

considerably within a store due to settlement and crusting. Similarly, the

composition of solid manure in a heap can vary depending on the amount of

bedding and losses of nutrients during storage. If stored materials are to be

analysed either in a laboratory or by a rapid on-farm method, it is important that

the sample taken represents an ‘average’ of what is found in the store or heap.

General principles of sampling: it is important, where this is practical and

safe, to take a number of samples. Take these from a range of positions within

the store or heap, bulk them together, mix them and then take a representative

sub-sample. You can send the final sample to the laboratory for analysis or test

it with a slurry N meter or slurry hydrometer on-farm.

Slurries: take at least five sub-samples of 2 litres, pour into a larger container, stir

thoroughly and pour a 2-litre sample immediately into a smaller clean container

to provide the sample for analysis.

• Above-ground stores: ideally, slurry should be fully agitated and sub-samples

taken from the reception pit. If this is not possible, and provided there is safe

access from an operator’s platform, the five sub-samples can be taken at a range

of positions, using a weighted 2-litre container attached to a rope.

• Below-ground pits: it may be possible to obtain sub-samples at various

positions using a weighted container as above, but never enter the pit, as

lethal gases may be present.

• Earth-banked lagoons: if the slurry has been well agitated, you can obtain

sub-samples from the tanker or irrigator as outlined below. Do not attempt to

sample direct from the lagoon unless there is a secure operator’s platform that

provides safe access.

• If the tanker is fitted with a suitable valve, it may be possible to take five

sub-samples from the stationary slurry tanker at intervals while field spreading

is in progress.

hours. Band spreaders, trailing shoe spreaders, injectors or rapid incorporation will

reduce odours and ammonia losses, whereas low trajectory broadcast spreaders

will only reduce some of the odours.

When spreading, the following key points will help you to avoid pollution and

possible associated fines.

Do not spread . . .

• within at least 10 metres of a ditch or watercourse or within 50 metres of a

spring, well or borehole that supplies water for human consumption or the

farm dairy;

• more than 50 m3 per hectare or 50 tonnes per hectare at one time, to reduce

the risk of runoff. Reduce these rates as necessary, so that the amount of total

nitrogen applied from organic manures does not exceed 250 kg per hectare

per year. Poultry manure will usually reach this loading at 5 to 15 tonnes

per hectare;

• when soils are frozen hard, that is, frozen for 12 hours or longer in the preceding

24-hour period;

• when the field is snow-covered;

• when the soil is cracked down to field drains or backfill;

• when fields have been pipe or mole drained, or sub-soiled over existing drains

within the last 12 months.

Timing of application: for optimum use of the available nutrients in manures,

they should be spread as close as possible before maximum crop growth and

nutrient uptake occur. For further information, see Booklets 1 and 2.

Remember, many people complain about unpleasant smells from farms.

Therefore, consider the following points before spreading.

• Do not spread in the evenings or at weekends, when people are more likely

to be at home.

• Pay attention to wind direction in relation to neighbouring houses.

• Avoid spreading under warm, humid conditions.

• Use spreading systems which minimise the production of dust or fine droplets.

10

13

Calibrating and operating spreaders

Application rate: to reduce the risk of pollution, the MAFF Water Code advises

limits for nutrient loading and volume applied. For example, the total N applied

from organic manures should not exceed 250 kg per ha per year. However, this is

the maximum limit and lower limits may be appropriate. Booklets 1 and 2 contain

further information on application rates. Once the desired application rate is

known, it is important to apply slurry or solid manure as accurately and as evenly

as possible.

How to estimate/measure application rate: there are international

standards for calibrating slurry and solid manure spreading systems. The full

calibration procedure determines the application rates achievable by the spreader

and how evenly slurry or solid manure is distributed. This is expressed as the

coefficient of variation or C of V. The equipment necessary to undertake this work

is large and expensive, but there are simple tests that can be conducted on farms.

Slurries: the application rate is affected by three factors:

• Discharge rate

• Bout width

• Forward speed.

Once the target application rate has been determined based on crop requirements

and available nutrients in the slurry, calculate the required forward speed to

achieve the target application rate as follows:

For a vacuum or pumped tanker, the discharge rate can be determined by filling

the tanker, of known volume, to its maximum capacity and timing how long the

tanker takes to empty under normal conditions, using the same pto speed that

would be used when spreading. Alternatively, the tanker could be weighed both

full and empty at a local weighbridge or on a farm vehicle weighing system to

determine its capacity.

Solid Manures: take at least ten sub-samples of about 1 kg each, taken as described

below, and place on a clean, dry tray or sheet. Break up any lumps and thoroughly

mix the sample and then take a representative sample of around 2 kg for analysis.

• Heaps: provided the manure is dry and safe to walk on, identify at least ten

locations which appear to be representative of the heap. Having cleared away

any weathered material with a spade or fork, dig a hole approx 0.5 metres

deep and take a 1kg sample from each point. Alternatively, take sub-samples

from the face of the heap at various stages during spreading.

• Weeping-wall stores: do not attempt to take samples before the store

is emptied as it is not safe to walk on the surface of the stored material.

Sub-samples may be taken from the face of the heap once emptying

has commenced.

Sampling during spreading: trays placed in the field can be used to collect

samples from the slurry or solid manure spreading system while the material is

being spread. Take care to avoid the possibility of injury from stones and other

objects which may be flung out by the spreading mechanism.

Sample analysis: the sample should be analysed for Dry Matter (DM), Total

Nitrogen (N), Ammonium-N (NH4+-N), Phosphorus (P), Potassium (K), Sulphur (S)

and Magnesium (Mg). There are further details on sample analysis in Booklets

1 and 2.

If you analyse slurry using an on-farm rapid method, do this immediately after

sampling, making sure that the sample taken is well mixed. If you send slurry to

a laboratory for analysis, samples should be dispatched in clean screw-topped

2-litre plastic containers. Leave at least 5 cm of airspace to allow the sample to

be shaken in the laboratory.

With manures, use 500-gauge polythene bags and expel excess air from the

bag before sealing. Clearly label the samples on the outside of the container or

bag and dispatch them immediately or within a maximum of seven days if kept

in a refrigerator.

12

Forward speed (km/hr) =Discharge rate (m3/second) x 36000

Bout width (m) x Application rate (m3/ha)

15

Solid manures: the application rate is affected by three factors:

• Discharge rate

• Bout width

• Forward speed.

Once the target application rate has been determined, based on crop requirements

and available nutrients in the solid manure, calculate the required forward speed

to achieve the target application rate as follows:

The discharge rate of a solid manure spreader can be determined by timing

how long the spreader takes to empty a complete load. Weigh the spreader both

empty and full at a local weighbridge or on a farm vehicle weighing system to

calculate the weight of manure. Due to variation in density of different manures,

you should calculate the discharge rate for each type of manure.

For rear discharge spreaders, the spread pattern is usually quite even and the

bout width can be taken as the spreading width. For both types of side discharge

spreader, it is much more difficult to establish the bout width. Generally, the

narrower the bout width, the lower the C of V, but as a general rule, the bout

width should be half the spreading width.

Figure 8 Bout width of broadcast spreaderFor a pumped tanker fitted with a positive displacement pump, the manufacturer

can supply pump performance charts from which the discharge rate can be

determined. This method of discharge rate determination can also be used for

umbilical systems and irrigators if they are fitted with a positive displacement pump.

If the system is fitted with a centrifugal pump, a flow meter should be used to

determine the discharge rate as the flow rate will vary with distance and height

pumped and with variation in slurry physical characteristics. However, discharge

rate can be easily estimated from the time taken to empty a tank of known

volume or weight.

For band spreaders, trailing shoe spreaders and injectors, the bout width is

simply the width of the boom or injector toolbar. For broadcast spreaders, it is

much more difficult to determine the bout width. Since the distribution of slurry

across the full spreading width of a broadcast spreader is not usually even, it is

important to overlap the bouts to achieve a low C of V. Generally, the narrower

the bout width, the lower the C of V, but as a general rule, the bout width should

be half the spreading width (see Figure 8).

14

Example The target Application Rate is 25 m3/ha. If a 10 m3 vacuum tanker

takes 300 seconds to empty, the Discharge Rate would be:

If the tanker was fitted with a 6 m spreading boom, the required

Forward Speed to achieve an Application Rate of 25 m3/ha would be:

The correct gear to achieve the required Forward Speed (km/hr) for

the given pto speed can then be selected from the gear chart in the

tractor cab.

Discharge Rate (m3/second) = = 0.033 m3/second10

300

Forward Speed (km/hr) = = 8 km/hr0.033 x 36000

6 x 25

Forward speed (km/hr) =Discharge rate (tonnes/second) x 36000

Bout width (m) x Application rate (m3/ha)

17

How to obtain more informationThe following are available FREE, unless otherwise stated.

• Fertiliser Recommendations for Agricultural and Horticultural Crops (MAFF, RB 209)Comprehensive reference book on use of organic manures and inorganic fertilisers.Seventh edition 2000, available from The Stationery Office – (£15) ISBN 0-11-243058-9.

Available from ADAS Gleadthorpe Research Centre. Tel: 01623 844331

• Managing Livestock Manures: Booklet 1 – Making better use of livestock manureson arable land (Second edition). ADAS, IGER, SRI

• Managing Livestock Manures: Booklet 2 – Making better use of livestock manures on grassland (Second edition). IGER, ADAS, SRI

Available from MAFF. Tel: 020 7238 6220

• MAFF/WOAD – Farm Waste Management Plan: A step-by-step guide for farmers.

Available from MAFF publications. Tel: 0645 556000

• The Water Code (Code of Good Agricultural Practice for the Protection of Water) – PB 0587. Information on farm waste management plans and avoiding water pollution.

• The Air Code (Code of Good Agricultural Practice for the Protection of Air) – PB 0618. Information on farm waste treatment, minimising odours and ammonia losses.

• The Soil Code (Code of Good Agricultural Practice for the Protection of Soil) – PB 0617. Information on soil fertility, erosion and contamination.

• Guidelines for Farmers in NVZs (PB 3277) and Manure Planning in NVZs (PB 3577)

The following are available free from local Health and Safety Executive offices.

• HSE Preventing Access to Effluent Storage and Similar Areas on Farms. HSE Information sheet AIS 9.

• HSE Managing Confined Spaces on Farms. HSE Information Sheet AIS 26.

• HSE Occupational Health Risks from Cattle. HSE Information Sheet AIS 19.

• National Farm Waste Management Plan Register – a list of local consultants whocan provide professional advice on waste management planning. Tel: 01398 361566

• MANNER (ADAS MANure Nitrogen Evaluation Routine) is a simple, personal computer-based decision-support system, supplied on CD-ROM or disk, with full instructions and aUser Guide. It can be obtained free of charge from:ADAS Gleadthorpe Research Centre, Meden Vale, Mansfield, Nottingham, NG20 9PFTel: 01623 844331 Fax: 01623 844472 or www.adas.co.uk/manner

For both slurry and solid manure, a crosscheck can be made by counting the

number of tanker or spreader loads and multiply by its capacity (m3 or tonnes),

to give the amount distributed on a field of known area. These tests, of course,

are not a substitute for comprehensive machine calibration, but they will give

a good indication of on-farm performance and will allow better use of the

available nutrients.

16

Example The target Application Rate is 30 tonnes/ha. If an 8 tonne rear

discharge spreader takes 300 seconds to empty, the Discharge Rate

would be:

If the spreader had a Bout Width of 4 m, the required Forward Speed to

achieve an application rate of 30 t/ha would be:

The correct gear to achieve the required Forward Speed (km/hr) for

the given pto speed can then be selected from the gear chart in the

tractor cab.

Discharge Rate (tonnes/second) = = 0.027 tonnes/second8

300

Forward Speed (km/hr) = = 8 km/hr0.027 x 36000

4 x 30

18

Volumes

1 imperial gallon (gall) = 0.0045 cubic metre (m3) 1 m3 = 220 gall1 imperial gallon (gall) = 4.55 litres (l) 1 litre = 0.22 gallons

Length

1 foot (ft) = 0.31 metre (m) 1 m = 3.28 ft

Speed

1 mile per hour (mph) = 1.61 kilometres per hour (km/h) 1 km/h = 0.62 mph

1 mile per hour (mph) = 0.45 metres per second (m/s) 1 m/s = 2.24 mph

Application rates

1 imperial gallon per acre (gall/ac) = 0.011 cubic metres per hectare (m3/ha) 1 m3/ha = 90 gall/ac

1 ton per acre (ton/ac)= 2.50 tonnes/hectare (t/ha) 1 t/ha = 0.40 ton/ac

Area

1 acre (ac) = 0.405 hectares (ha) 1 ha = 2.47 ac

Fertilisers

1 unit per acre (unit/ac)= 1.25 kilograms/hectare (kg/ha) 1 kg/ha = 0.8 units/ac

1 kg P = 2.29 kg P2O5 1 kg P2O5 = 0.44 kg P1 kg K = 1.20 kg K2O 1 kg K2O = 0.83 kg K1 kg S = 2.50 kg SO3 1 kg SO3 = 0.40 kg S1 kg Mg = 1.66 kg MgO 1 kg MgO = 0.60 kg Mg

Conversion table