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y=0.46x+0.20

R

2

=0.58; p<0.001

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Evidence Project Final Report

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Project identification

1.Defra Project code

SCF0202

2.Project title

Analysing the characteristics of UK pig and poultry manures and slurries

3.Contractororganisation(s)

ADAS UK Ltd

Gleadthorpe

Meden Vale

Mansfield

Nottinghamshire

NG20 9PD

54.Total Defra project costs

£42,619

(agreed fixed price)

5.Project:start date

1st August 2014

end date

31st March 2015

6.It is Defra’s intention to publish this form.

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Executive Summary

7.The executive summary must not exceed 2 sides in total of A4 and should be understandable to the intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together with any other significant events and options for new work.

The current data on livestock manure nutrient contents published in the 8th edition of Defra’s “The Fertiliser Manual (RB209)” (Anon, 2010) was collated by ADAS in 2003, based on data from the Manure ANalysis DatabasE (MANDE) project (Defra project NT2006). Samples of stored slurry, solid manures and dirty water (from cattle, pig, poultry and sheep units) were collected between April 2000 and December 2002, as part of a surveillance project measuring pathogen levels in farm manures (FSA project BO5003), and were further analysed for a range of chemical properties i.e. pH, dry matter (DM), total nitrogen (N), phosphorus (P), potassium (K), sulphur (S), magnesium (Mg), ammonium-N, nitrate-N, uric acid N (poultry manures), organic carbon (OC), C:N ratio and electrical conductivity (EC). The results were combined with manure analysis data collected by ADAS as part of other Defra-funded research projects undertaken in the 1990s, to provide a database of over 800 individual manure samples. These data were subsequently used to establish the ‘typical’ manure nutrient contents used in the 8th edition of RB209. However the data on livestock manure composition on which RB209 guidance is based may now be out of date due to change to pig and poultry diets, and housing and manure management systems which have occurred since the underlying data were collected.

The aim of this project was to ensure that RB209 data on the ‘typical’ N, P, K, S and Mg concentrations of pig and poultry manures are up-to-date and representative, so that RB209 continues to provide accurate and relevant nutrient management advice for farmers and growers.

A number of changes to industry pig and poultry production practices which are likely to have had some effect (to varying degrees) on manure nutrient characteristics were identified, including:

· The introduction of phytase into pig and poultry diets, thus reducing the need for supplemental inorganic P and improving the nutritional value of feedstuffs. This would be expected to reduce pig and poultry manure P concentrations.

· Improvements to pig feed conversion ratios, together with reductions in the crude protein content of pig diets and the use of supplementary synthetic amino acids, is likely to affect how much of the nutrient content of the feeds is utilised by the animal, and how much is collected in the excreta.

· The move to on-belt manure removal or deep litter systems for laying hens, and the increased use of heat exchange units for broilers, would be expected reduce manure dry matter content and increase manure nutrient concentrations and the proportion of readily available N present as uric acid-N content.

A targeted sampling scheme was undertaken to address identified deficiencies in the RB209 manure data by providing updated information on the dry matter (DM), total N, readily available N (RAN i.e. N in the ammonium form plus N present as uric acid in poultry manures), P, K, Mg, S, volatile solids (VS) and biodigestability (B0) of litter/manure/slurry. Samples of pig slurry and FYM, layer manure, broiler litter, turkey litter and duck FYM were collected throughout England and Wales during 2014 (112 samples) and analysed using standard methods. These data were combined with supplementary data collected during the course of other recent research projects (181 samples) to provide a comprehensive and up to date manure analysis database for pig and poultry manures. Where possible, the data were analysed using two-sample t-tests to determine whether there were significant differences between the nutrient contents of the ‘new’ data and the old MANDE database for each manure type. This allowed us to determine whether the results from the sampling programme justify an update of the RB209 ‘typical’ manure nutrient contents.

The results of the study indicated that since the previous sampling was undertaken in 2000/2002:

· Pig slurry total N and RAN concentrations have increased by a small amount (from 3.6 to 4.1 kg/t total N and from 2.5 to 2.7 kg/t RAN for a 4% DM slurry), whilst phosphate concentrations have decreased (from 1.8 to 1.6 kg/t for a 4% DM slurry) reflecting the widespread use of dietary phytase. Concentrations of the other nutrients in pig slurry are very similar to the previous values.

· There have been no statistically significant changes to the dry matter or nutrient concentrations of pig FYM.

· The dry matter content of layer manure has increased substantially from 35 to 48 %, (mainly as a result of the increased use of on-belt manure removal systems) leading to increased nutrient concentrations.

· For both layer manures and broiler/turkey litter a greater proportion of the RAN was present in the form of uric acid-N which is likely to have important implications for ammonia losses during housing, storage and land spreading, and crop N use efficiency.

· The phosphate concentration of broiler litter has significantly reduced following the introduction of dietary phytase; however, concentrations of potash and magnesium have significantly increased in response to the increased use of soya and improvements in feed digestibility.

· The magnesium concentration of duck FYM has significantly increased as a result of improvements to duck genotypes and feed digestibility, although no changes were measured in the concentrations of other nutrients.

It is important that the typical manure nutrient analyses published in RB209 are accurate; this ensure that the fertiliser replacement value of manure applications are maximised and losses to the environment are minimised. Overall the results of the project suggest that some of the manure analysis figures in the 8th Edition of Defra’s Fertiliser Manual (RB209) should be updated. In particular, the total N and RAN content of pig slurry should be increased and the phosphate content of broiler litter should be reduced. Changes to the pig slurry total and readily available N contents will improve manure N use efficiency, reduce the need for manufactured fertiliser N applications to meet crop requirements, and reduce the potential for N losses to the environment (i.e. nitrate leaching to water, and ammonia and nitrous oxide emissions to air). Changes to the phosphate content of broiler litter will reduce the risks of over supplying phosphate and the potential for phosphorus losses to water.

In addition, we recommend that the values for poultry manure (layer manure, and broiler and turkey litter) are given for a typical range of dry matter contents as is currently the case for slurries

Further work is required to quantify the effect of the higher uric-acid N content of poultry manures on manure N use efficiency and on ammonia emissions during housing and manure storage and following application to land. The information will be important to meet the requirements of future revisions of the Nitrate Vulnerable Zone Action programme and to support Defra’s policy to meet the requirements of the National Emissions Ceilings Directive.

Project Report to Defra

8.As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with details of the outputs of the research project for internal purposes; to meet the terms of the contract; and to allow Defra to publish details of the outputs to meet Environmental Information Regulation or Freedom of Information obligations. This short report to Defra does not preclude contractors from also seeking to publish a full, formal scientific report/paper in an appropriate scientific or other journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms. The report to Defra should include:

the objectives as set out in the contract;

the extent to which the objectives set out in the contract have been met;

details of methods used and the results obtained, including statistical analysis (if appropriate);

a discussion of the results and their reliability;

the main implications of the findings;

possible future work; and

any action resulting from the research (e.g. IP, Knowledge Exchange).

Table 2.7. Dry matter and nutrient contents of pig FYM (fresh weight basis)

Manure property

Current RB209/

MANDE value

Updated data (n=104)

Mean*

Median

Range

Dry matter (%)

25

24 (ns)

22

12-51

Total N (kg/t)

7.0

7.7 (ns)

7.7

1.0-21

RAN (kg/t)1

1.0 (old)2

1.8 (fresh)3

0.82

1.83

-

-

-

-

Total P2O5 (kg/t)

6.0

5.7 (ns)

5.2

0.8-22

Total K2O (kg/t)

8.0

7.4 (ns)

6.5

1.0-26

Total SO3 (kg/t)

3.4

3.9 (ns)

3.3

0.7-12

Total MgO (kg/t)

1.8

2.1 (ns)

2.0

0.4-7.9

1RAN is the N in the ammonium-N form

2Old FYM is FYM that has been stored for 3 months or more (11 samples); t-test comparison not undertaken.

3Fresh FYM is FYM that is spread straight from the building (16 samples); t-test comparison not undertaken.

*The p value (in brackets) indicates whether the updated mean value is significantly different from the current RB209/MANDE value; ns= not significant

2.2.3 Poultry manures

Table 2.6 compares the nutrient contents of the 31 layer manure samples with current RB209/MANDE values. This indicates that the mean DM content has increased significantly (p<0.001) from 35% to around 48%, as predicted from the change to on-belt manure removal systems which produce drier layer manure (see Work Package 1). There was a wide range of layer manure DM contents (22-85%) reflecting the different housing/production systems from which the manures were collected (including cage systems with deep pit or belt-scraped manure removal systems, and free range birds).

Because layer manure nutrient concentrations are related to DM (see discussion below) this change will affect the concentrations of N and other nutrients. Despite the increase in DM content, layer manure total N, RAN and P2O5 concentrations remained similar (p>0.05) at 21, 8.2 and 15 kg/t, respectively. However, the composition of the RAN had significantly changed, with the ammonium-N concentration decreasing from 6.0 to 3.5 kg/t and the uric acid-N concentration increasing from 3.0 to 4.5 kg/t. Thus a greater proportion of the RAN was in the form of uric acid-N, probably because less N had been hydrolysed to the ammonium form due to the higher DM content of the manures. The potash, sulphur and magnesium concentrations have all increased significantly (p<0.001) compared to the current RB209 published values, which is in line with the increase in DM content.

Table 2.7 compares the nutrient contents of the 48 broiler/turkey samples with current RB209 values. This indicates that there has been no significant change (p>0.05) in the DM, total N, RAN or sulphur concentrations of the litter despite the increased use of heat exchange units. As with the layer manures, the composition of the RAN had significantly changed, with the ammonium-N concentration decreasing from 5.7 to 4.0 kg/t and the uric acid-N concentration increasing from 3.9 to 5.0 kg/t. Thus a greater proportion of the RAN was present in the form of uric acid-N which could have important implications for ammonia losses from the litter during housing, storage and land spreading, because ammonia loss does not start until the uric acid-N has been converted into ammonium-N. There could also be consequences for crop N use efficiency if less N is lost through ammonia volatilisation.

The range in litter DM contents (39-80%) was narrower than for layer manure and largely driven by the type and quantity of bedding material supplied; of the most widely used bedding materials, straw tends to be less absorbent than woodshavings and hence would produce lower DM litter. Litter P2O5 concentrations have decreased significantly (p<0.001) from 25 to 15 kg/t, probably as a result of the use of dietary phytase. Higher phytase levels and more efficient phytases enable a greater release of P from plant-based feed and so less mineral P is added to diets in the form of calcium phosphates. In some cases, there may also have been a reduction in P specifications for feeds in response to recent shortages of rock phosphate. Potash concentrations may have increased (from 18 to 21 kg/t) because of the use of higher protein feeds, related to the higher amino acid specifications which are needed for modern poultry genotypes. This leads to more soya being used in feed than previously, and many companies have reduced or dropped fishmeal from their formulations either for cost reasons or because some retailers want birds fed on vegetable-based feeds. Soya is high in K so both of these changes will have tended to increase K concentrations in the feed and hence in the excreta. It is not clear why magnesium concentrations have also increased (from 4.4 to 5.8 kg/t) as Mg is not routinely added to poultry diets, although it may be related to changes in feed digestibility.

Table 2.6. Dry matter and nutrient contents of layer manure (fresh weight basis)

Manure property

Current RB209/

MANDE value

Updated data (n=31)

Mean*

Median

Range

Dry matter (%)

35

48 (p<0.001)

44

22-85

Total N (kg/t)

19

21 (ns)

19

9.1-40

Ammonium-N (kg/t)

6.0

3.5 (p<0.001)

3.4

0.9-6.9

Uric acid-N (kg/t)

3.0

4.5 (p<0.05)**

3.8

0-15.8

RAN (kg/t)1

9.5 (RB209)

9.0 (MANDE)

8.2 (ns)

7.1

3.5-17

Total P2O5 (kg/t)

14

15 (ns)

14

6.8-27

Total K2O (kg/t)

9.5

15 (p<0.001)

15

6.8-25

Total SO3 (kg/t)

4.0

5.7 (p<0.001)

5.4

2.3-9.9

Total MgO (kg/t)

2.6

4.4 (p<0.001)

3.8

1.9-7.5

1RAN is the N in the ammonium-N plus uric acid-N form. Note: the value given in RB209 is not the same as the sum of the ammonium-N and uric acid-N values in the MANDE database

*The p value (in brackets) indicates whether the updated mean value is significantly different from the current RB209/MANDE value; ns= not significant

**t-test conducted on log transformed data

Table 2.7. Dry matter and nutrient contents of broiler/turkey litter (fresh weight basis)

Manure property

RB209/MANDE value

Updated data(n=48)

Mean*

Median

Range

Dry matter (%)

60

57 (ns)

56

39-80

Total N (kg/t)

30

28 (ns)

29

5.5-43

Ammonium-N (kg/t)

5.7

4.0 (p<0.001)

4.2

0.3-9.0

Uric acid-N (kg/t)

3.9

5.0 (p<0.05)**

5.1

0-10.9

RAN (kg/t)1

10.5 (RB209)

9.6 (MANDE)

9.1 (ns)

10.0

0.1-14

Total P2O5 (kg/t)

25

15 (p<0.001)

16

6.0-25

Total K2O (kg/t)

18

21 (p<0.05)

20

4.9-29

Total SO3 (kg/t)

8.0

8.2(ns)

8.3

2.0-12

Total MgO (kg/t)

4.4

5.8 (p<0.001)

5.6

3.6-8.6

1RAN is the N in the ammonium-N plus uric acid-N form. Note: the value given in RB209 is not the same as the sum of the ammonium-N and uric acid-N values in the MANDE database

*The p value (in brackets) indicates whether the updated mean value is significantly different from the current RB209/MANDE value; ns= not significant

**t-test conducted on log transformed data

The possibility of combining the data on layer manure and broiler/turkey litter into a single poultry manure database was also explored to determine whether poultry manure nutrient contents are driven by manure DM content, as previously reported by Nicholson et al. (1996) and implemented in MANNER-NPK and PLANET. This analysis clearly showed strong and highly significant (p<0.001) linear relationships between poultry manure dry matter contents and the total N (Figure 2.5), phosphate, potash, sulphur and magnesium contents (Table 2.8), with no distinction between the relationships for layer manure and broiler litter. The relationship between poultry manure DM and RAN contents was weaker (r2= 0.14; p<0.01), although when RAN was expressed as a percentage of the total N content, there was a significant (r2= 0.28; p<0.001) inverse relationship with DM content (Figure 2.6; Table 2.8).

Figure 2.5. Relationship between poultry manure dry matter (%) and total N (kg/t) contents.

0.05.010.015.020.025.030.035.040.045.0020406080100Total N (kg/t)Dry matter (%)Broiler/TurkeyLayer

Figure 2.6. Relationship between poultry manure dry matter (%) and RAN (% total N) contents.

0.010.020.030.040.050.060.070.0020406080100RAN (% total N)Dry matter (%)Broiler/TurkeyLayer

This would indicate that the RB209 ‘standard’ figures for poultry manure (layer manure, and broiler and turkey litter) could be combined and given for a typical range of dry matter contents as is currently the case for slurries. Suggested values, calculated using the regression equations in Table 2.8, are presented in Tables 2.9 and 2.10.

Table 2.8. Relationships between dry matter (%) and nutrient contents of poultry manures.

Nutrient

Linear regression

Total N (kg/t)

N = 0.20 + 0.46 DM (n=79; r2=0.58; p<0.001)

RAN (kg/t)

RAN = 4.54 + 0.08 DM (n=74; r2=0.14; p<0.01)

RAN (% total N)

RAN = 55.2 - 0.36 DM (n=74; r2=0.28; p<0.001)

Phosphate (kg/t)

P2O5 = 3.62 + 0.22 DM (n=79; r2=0.43; p<0.001)

Potash (kg/t)

K2O = 2.48 + 0.30 DM (n=79; r2=0.59; p<0.001)

Sulphur (kg/t)

SO3 = 0.39 + 0.13 DM (n=79; r2=0.58; p<0.001)

Magnesium (kg/t)

MgO = 1.10 + 0.08 DM (n=79; r2=0.48; p<0.001)

Table 2.9. Current RB209/MANDE and suggested revised total and readily available N (RAN) contents for poultry manures.

Dry matter (%)

Total N (kg/t fw)

RAN (kg/t fw)

Current

Revised

Current

Revised

20

-

9.4

-

4.5

35 (layer)1

19

-

9.5

-

40

-

19

-

7.8

60 (broiler)2

30

28

10.5

9.4

80

-

37

-

9.8

1RB209 currently gives a typical dry matter content of 35% for layer manure

2RB209 currently gives a typical dry matter content of 60% for broiler/turkey litter

Table 2.10. Current RB209/MANDE and suggested revised nutrient contents for poultry manures.

Dry matter (%)

P2O5 (kg/t fw)

K2O (kg/t fw)

SO3 (kg/t fw)

MgO (kg/t fw)

Current

Revised

Current

Revised

Current

Revised

Current

Revised

20

-

8.0

-

8.5

-

3.0

-

2.7

35 (layer)1

14

-

9.5

-

4.0

-

2.6

-

40

-

12

-

15

-

5.6

-

4.3

60 (broiler)2

25

17

18

21

8.0

8.2

4.4

5.9

80

-

21

-

27

-

11

-

7.5

1RB209 currently gives a typical dry matter content of 35% for layer manure

2RB209 currently gives a typical dry matter content of 60% for broiler/turkey litter

2.2.3 Duck manure

Table 2.11 compares the nutrient contents of the 6 duck manure samples with current RB209 values, which given the variability of the data, would only detect differences of 50% or more from current RB209 guideline values (see Appendix 1). The results show that there has been no significant change (p>0.05) in the DM or nutrient concentrations of duck manures, except for magnesium which has increased from 1.2 to 2.4 kg/t. This may be because overall feed digestibility for ducks has improved since 2000 (in line with genetic progress which has been improving at a faster rate than for other poultry), and so the concentration in excreta has increased.

Table 2.11. Dry matter and nutrient contents of duck manure (fresh weight basis)

Manure property

RB209/MANDE value

Updated data(n=6)

Mean*

Median

Range

Dry matter (%)

25

24 (ns)

25

20-29

Total N (kg/t)

6.5

7.8 (ns)

7.7

4.1-13

RAN (kg/t)1

1.0 (old)

1.6 (fresh)

1.9 (ns)

1.2

0.1-6.9

Total P2O5 (kg/t)

5.5

6.5 (ns)

6.2

2.8-13

Total K2O (kg/t)

7.5

8.5 (ns)

7.4

2.7-16

Total SO3 (kg/t)

2.6

3.2 (ns)

3.3

1.6-4.6

Total MgO (kg/t)

1.2

2.4 (p<0.01)

2.3

1.2-4.4

1RAN is the N in the ammonium-N plus uric acid-N form

*The p value (in brackets) indicates whether the updated mean value is significantly different from the current RB209/MANDE value; ns= not significant

2.2.4. Volatile solids and biodigestibility

Information on manure volatile solids content and biodigestibility is mainly of interest from a biogas or emissions accounting perspective. The results of these analyses will reported in a supplementary Annexe to this report.

Work Package 3: IMPLICATIONS FOR FERTILISER ADVICE AND ENVIRONMENTAL IMPACTS

The objective of this Work Package was to estimate the impact that a revision of the ‘typical’ manure nutrient content data would have on fertiliser advice, including consideration of the agronomic and environmental impacts any change in guidance would have.

3.1 THE IMPORTANCE OF NUTRIENTS IN PIG AND POULTRY MANURES

Data from Manures-GIS (Defra project WQ0103) show that pig and poultry manures are an important source of crop nutrients, respectively contributing around 10% and 19% of the total N applied to agricultural land within handled livestock manures in England and Wales, around 7% and 26% of total P additions, and around 7% and 16% of total K additions (Table 3.1). Also, pig and poultry manure production is largely concentrated in the east of the country (Figure 3.1) and so the majority of pig manure (c.85%) and poultry manure (c.95%) is applied to arable land, which is also located largely in the east (Figure 3.2). Where farmers rely on the ‘typical’ or ‘standard’ nutrient values of manures published in RB209, changes to these values could have a significant effect on the nutrients estimated to be potentially available for arable crop uptake, and hence on the use of manufactured fertilisers on these crops.

Table 3.1. Total annual quantities of nutrients (Kt) in handled manures and directly deposited excreta in England and Wales (Data from Manures-GIS)

Total N

Total P

Total K

Sector

Solid manure

Slurry

Excreta deposited

Solid manure

Slurry

Excreta deposited

Solid manure

Slurry

Excreta deposited

Dairy

46

75

90

10

16

15

43

59

54

Beef

72

20

136

14

4

20

66

24

87

Sheep

6

-

142

2

-

22

11

-

197

Pigs

20

12

4

4

3

1

10

7

2

Laying hens

11

-

1

4

-

<1

9

-

<1

Broilers

48

-

1

15

-

<1

33

-

<1

Total

203

107

374

49

23

59

171

90

341

3.2 EFFECTS OF CHANGES TO PIG AND POULTRY MANURE ‘TYPICAL’ NUTRIENT VALUES

The likely financial, agronomic and environmental impacts of revising RB209 ‘typical’ nutrient values depends on the magnitude of the change to the mean nutrient contents of pig and poultry manures in relation to current typical values published in RB209. Data from this study have indicated that there have been some changes to the mean ‘typical’ manure dry matter and nutrient concentrations. Most notably, for poultry manures the phosphate concentration has decreased whilst the potash and magnesium concentrations have increased; there have also been some increases in the total N concentration of pig slurry The nutrient concentrations in pig FYM were not significantly different from the previous RB209 value.

The tables of typical manure nutrient contents (or the typical manure figures in MANNER-NPK and PLANET into which the same values are embedded) are used to calculate manure nutrient supply and adjust manufactured fertiliser applications to meet crop demand. The manure analysis data are also used by farmers and regulators to show compliance with Nitrate Vulnerable Zone Action Plan requirements. Accurate information on manure nutrient content is essential to maximise nutrient use efficiency, farm profitability (through avoiding unnecessary fertiliser applications or reductions in crop yield and quality) and minimise the risks of nutrient losses to air (i.e. ammonia and nitrous oxide) and water (i.e. nitrate-N, ammonium-N and phosphorus). Under-estimating the nutrient content of livestock manures could lead to nutrient applications in excess of crop demand, increasing the risk to crop yields and quality including lodging in cereals, elevated amino-N concentrations in sugar beet, high grain N content of barley, excessive ammonia concentrations in grass silage and reduced tuber numbers in potato crops. Excessive nutrient applications will increase the risks of ammonia and nitrous oxide emissions to air and nitrate-N, ammonium-N and phosphorus losses to water. Over-estimating manure nutrient contents will result in nutrient applications that are insufficient to achieve optimum yields reducing farm incomes and food production.

Figure 3.1. Quantities of handled (a) pig and (b) poultry manures produced annually in England and Wales. (Source: MANURES-GIS using 2010 Agricultural Census data)

a) Pig manure

b) Poultry manure

Figure 3.2. Arable land in England and Wales (areas with a high proportion of arable land shown in green)

The study has also shown that changes to poultry manure management systems have increased the proportion of poultry manure total N which is present in the form of uric acid. Uric acid is hydrolysed by the action of aerobic bacteria to form urea and then ammonium-N. This process occurs more rapidly in moist conditions, hence drier poultry manures tend to retain a higher proportion of N in the uric acid-N form. This also means that N losses via ammonia volatilisation occur more slowly than if N was present in the ammonium-N form, such that ammonia losses during storage are likely to be lower from drier manures, with more N remaining when the manure is spread to land. Also, if these drier poultry manures are incorporated into the soil shortly after spreading (i.e. within 24 hours), much of the N they contain could be conserved in the soil for uptake by the growing crop, thereby increasing the manure N use efficiency and increasing the risk of nitrous oxide emissions.

The data from this study have indicated that for broiler/turkey litter, the phosphate content has decreased from a mean of 25 kg/t in the 8th Edition of RB209 to around 17 kg/t; see Table 2.10). We used MANNER-NPK (Nicholson et al., 2013) to assess how these changes would affect manufactured fertiliser use by a farmer relying on the current RB209 tables. Thus a typical broiler litter application of 8 t/ha would be estimated to supply the crop with 136 kg/ha, compared with 200 kg/ha if the current RB209 ‘typical’ analysis was used (Table 3.2). In contrast, increases in the potash and magnesium concentrations of broiler litter mean that the farmer could have achieved substantial savings in the amount of manufactured potash and magnesium fertilisers applied by taking account of the greater quantities supplied by the broiler litter application.

Table 3.2. MANNER-NPK estimates* of the nutrient value of a 8 t/ha broiler litter application using current RB209 typical nutrient concentrations and values based on the updated data.

Based on current RB209 typical broiler litter analysis values

Actual (based on updated broiler litter analysis data)

Total N applied (kg/ha)

240

224

Phosphate applied (kg/ha)

200

136

Potash applied (kg/ha)

144

168

Sulphur applied (kg/ha)

64

66

Magnesium applied (kg/ha)

35

47

Potential financial value of manure application (£/ha)

309

267

*MANNER-NPK estimates are based on 8 t/ha of broiler litter broadcast applied (then ploughed in within 12-24 hours) on 1st September to a medium/heavy soil in central England growing a late sown winter cereal crop.

The data from this study have also indicated that there have been some changes in typical pig slurry total N and readily available N contents. Table 3.3 compares the estimated nutrient value of a 50 m3/ha pig slurry application (4% dry matter) based on current RB209 ‘typical’ figures compared with the suggested revised values and shows that there is a difference of c.25 kg/ha total N in the estimates of total N applied. In view of this, it is likely that some farmers/advisers using the current RB209 standards are over-applying pig slurry and not taking adequate account of its actual N (and other nutrient) value. If the RB209 ‘typical’ total N value for pig slurry is increased from the current 3.6 kg/m3 to 4.1 kg/m3 (see Table 2.5), farmers basing their manure plans on ‘typical’ figures are likely to reduce their application rates and apply their manure over a larger area increasing manure nutrient use efficiency.

Table 3.3 shows that a farmer who relies on the current RB209 typical nutrient analysis table for a pig slurry application of 50 m3/ha would actually be applying 25 kg/ha more total N than anticipated. The quantity of readily available N supplied by the manure would be 10 kg/ha more than expected, therefore the farmer could have applied 10 kg/ha less manufactured fertiliser to achieve the same crop yield saving c.£9/ha in production costs at current N fertiliser prices. There would be more N than ‘necessary’ lost via nitrate leaching and ammonia volatilisation, in addition to the environmental losses from the excess manufactured fertiliser N applied which would not be taken up by the crop.

Table 3.3. MANNER-NPK estimates* of N losses and nutrient value of a 50 m3/ha pig slurry application (4% dry matter) using current RB209 typical nutrient concentrations and values based on the updated data.

Based on current RB209 typical pig slurry analysis values

Actual (based on updated pig slurry analysis data)

Total N applied (kg/ha)

180

205

N mineralised (kg/ha)

7

9

N leached (kg/ha)

9

10

Ammonia losses (kg/ha)

32

34

Denitrification losses (kg/ha)

7

8

Crop N uptake (kg/ha)

84

92

Manure N efficiency (%)

46

45

*MANNER-NPK estimates are based on 50 m3/ha of pig slurry broadcast applied on 1st March to a medium/heavy soil in central England growing a late sown winter cereal crop.

4. CONCLUSIONS

· Pig and poultry manures are important sources of plant nutrients to arable crops; changes to their ‘typical’ nutrient values published in RB209 could affect manure application rates and the quantities of manufactured fertilisers used on these crops.

· Results from the current sampling programme have indicated that since the previous sampling was undertaken in 2000/2002:

· Pig slurry total N and RAN concentrations have increased by a small amount (from 3.6 to 4.1 kg/t total N and from 2.5 to 2.7 kg/t RAN for a 4% DM slurry), whilst phosphate concentrations have decreased (from 1.8 to 1.6 kg/t for a 4% DM slurry) reflecting the widespread use of dietary phytase. Concentrations of the other nutrients in pig slurry are very similar to the previous values.

· There have been no statistically significant changes to the dry matter or nutrient concentrations of pig FYM.

· The mean dry matter content of layer manure has increased from 35 to 48 %, due to changes in the design of laying hen housing systems with increased use of deep litter, on-belt manure removal systems and free range production. The higher dry matter content of the layer manure has affected manure nutrient concentrations.

· For both layer manures and broiler/turkey litter a greater proportion of the RAN was present in the form of uric acid-N which will have important implications for ammonia losses during housing and manure storage and following land spreading of manure. The increased uric-acid N content is also likely to affect manure N use efficiency.

· The phosphate concentration of broiler litter has significantly reduced following the introduction of dietary phytase; however, concentrations of potash and magnesium have significantly increased.

· The magnesium concentration of duck FYM has significantly increased, although there have been no changes in the concentrations of other nutrients.

· The results of this project suggest that the current manure analyses in Defra’s Fertiliser Manual RB209 should be updated to reflect increases in the N concentration of pig slurry and reductions in the phosphate content of poultry manures.

· Inaccurate information on manure nutrient contents will affect farm profitability by causing either excessive or inadequate nutrient supply which will reduce crop yields and quality and increase the risk of nutrient losses to air (i.e. ammonia and nitrous oxide emissions) and water (i.e. nitrate-N, ammonium-N, and phosphorus).

· Based on this study, revised ‘typical’ pig and poultry manure nutrient contents have been suggested for publication in the next revision of RB209. We recommend that the values for poultry manure (layer manure, and broiler and turkey litter) are given for a typical range of dry matter contents as is currently the case for slurries.

Further research is required to quantify the impact that the production of drier layer manures from contemporary poultry management systems has on ammonia emissions from housing, during manure storage and following land spreading. This information is required to provide fit for purpose ammonia emission factors for the UK Ammonia Emissions Inventory and to support Defra’s policy needs to meet the requirements of the revisions to the EC National Emissions Ceilings Directive, which propose an 8% reduction in ammonia emissions from 2005 levels in any year from 2020-29 and a 21% reduction in any year from 2030. The current emission factors for laying hen manure management systems are out of date because they are based on data derived from deep pit systems which are being phased out. There is also a need to quantify the N use efficiency of the drier layer manure, which is needed to update the manure N use efficiency values used to support Defra’s policy needs to meet the requirements of the EC Nitrates Directive, which are also currently based on deep pit layer manure.

References to published material

9.This section should be used to record links (hypertext links where possible) or references to other published material generated by, or relating to this project.

Table A1. Number of samples required to detect a 20% difference from the current RB209/MANDE value for a manure property and the number of samples to be collected as part of this study.

Manure type

Total N

RAN

P2O5

K2O

MgO

SO3

DM

Recent projects

This study

Total

Pig FYM

11

65

23

36

18

24

11

78

26

104

Broiler/turkey

11

5

11

8

10

18

5

10

38

48

Layer

13

10

17

14

12

12

10

4

27

31

Duck

16

64

26

22

34

24

8

0

6

6

Table A2. Number of samples required to detect a 10% difference from the current RB209/MANDE value for a manure property and the number of samples to be collected as part of this study.

Manure type

Total N

RAN

P2O5

K2O

MgO

SO3

DM

Recent projects

This study

Total

Pig FYM

42

261

92

145

72

94

46

78

26

104

Broiler/turkey

43

21

45

33

39

71

19

10

38

48

Layer

52

42

68

56

48

48

38

4

27

31

Duck

64

254

104

88

134

94

32

0

6

6

�

y=-0.36x+55.2

R2=0.28; p<0.001)

EVID4 Evidence Project Final Report (Rev. 06/11)Page 1 of 25