Algorithms for variable-rate application of manure

Transcription

Baltic Forum for Innovative Technologies for Sustainable Manure Management
KNOWLEDGE REPORT
Algorithms for variable-rate application
of manure
By Daniel Rückamp, Judith Schick, Silvia Haneklaus and Ewald Schnug
WP4 Standardisation of Manure Types with Focus on Phosphorus
October 2013
Baltic Manure WP4
Standardisation of Manure Types with Focus on Phosphorus
Algorithms for variable-rate application
of manure
By Daniel Rückamp, Judith Schick, Silvia Haneklaus and Ewald Schnug
Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI),
Institute for Crop and Soil Science
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Preface
An undesired surplus of nutrients in agricultural soils can be attributed among others to a
uniform application of fertilisers as it does not address the small-scale variation of nutrients
in soils. Site-specific fertilisation can reduce nutrient surpluses. The present report aims to
introduce the legal framework of manure application in countries of the Baltic Sea region, to
describe the advantages and disadvantages of fertilisation with manure in relation to
mineral fertilisers, to give an overview about the nutrient composition and amount of slurry
in relation to animal species and feeding regime, and to develop algorithms for the variablerate application of slurry.
This report was compiled and edited by Daniel Rückamp, Judith Schick, Silvia Haneklaus and
Ewald Schnug (WP4 leader, JKI). It is written as part of work package 4 “Standardisation of
manure types with focus on Phosphorus” of the project “Baltic Forum for Innovative
Technologies for Sustainable Manure Management” (Baltic Manure). The project aims at
turning manure problems into business opportunities and is partly funded by the European
Union European Regional Development Fund (Baltic Sea Region Programme 2007- 2013).
The authors would like to thank Alar Astover (EMU, Estonia), Andras Baky (JTI, Sweden),
Andreas Berk (FLI, Germany), Juha Grönroos (SYKE, Finland), Allan Kaasik (EMU, Estonia),
Ksawery Kuligowski (POMCERT, Poland), Andrea Meyer (LWK Niedersachsen, Germany),
Ulrich Meyer (FLI, Germany), Hanne Damgaard Poulsen (Aarhus University, Denmark), Lena
Rodhe (JTI, Sweden), Jakub Skorupski (Green Federation GAJA, Poland), Annette Vibeke
Vestergaard (Videncentret for Landbrug, Denmark), and Kari Ylivainio (MTT, Finland). They
gave input to the legal standards, to the animal feeding, to the separation of slurry and to
the manuscript in general.
October 2013
The authors
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Table of Contents
1
Introduction .............................................................................................................. 4
2
Legal framework for manure application ................................................................... 6
3
Advantages and disadvantages of mineral fertilisers and slurry................................ 11
4
Factors influencing the mineral composition of slurry .............................................. 13
5
Variable-rate slurry application ............................................................................... 24
6
5.1
Prerequisites ............................................................................................................... 24
5.2
Online-Measurement of manure composition .............................................................. 25
5.3
Strategies for manure production ................................................................................ 26
5.4
Additional application of mineral fertilisers .................................................................. 27
Algorithms for the variable-rate application of slurry ............................................... 28
6.1
Prerequisites ............................................................................................................... 28
6.2
Combined application of slurry and single-nutrient mineral fertiliser ............................ 28
6.3
Crop rotation ............................................................................................................... 40
7
Conclusions ............................................................................................................. 43
8
References .............................................................................................................. 44
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1
Introduction
Codes of Good Agricultural Practice imply the statuary law on management practices that
can be adopted to minimise the risk of water, air and soil pollution (Schnug et al., 2011).
Especially an undesired surplus of nitrogen (N) and phosphorus (P) on agricultural land as a
result of an improper fertiliser use may lead to an increased nutrient discharge into water
bodies. The nutrient surplus can be – among other factors – attributed to constant nutrient
ratios of mineral multi-nutrient and organic fertilisers during the application. Usually, soil
parameters and accordingly soil fertility vary naturally within one single field. Thus, a
uniform application of fertilisers results in an imbalanced fertiliser application and
consequently to unnecessary environmental impacts (Figure 1; Burrough, 1993; Haneklaus et
al., 1998b; Haneklaus and Schnug, 2000).
Figure 1 Discrepancy between site-specific nutrient demand and uniform fertiliser rates (adapted
from Schnug et al., 2011).
Usually, the balance of big livestock farms exhibits the highest nutrient surpluses
(130-250 kg N ha-1, 90 kg P ha-1) (Haneklaus et al., 1998), which are caused by improper use
of manure. Hence, manure is a major contributor to an increased nutrient input into the
Baltic Sea region (BSR). Thus it may be concluded that a sustainable use of this valuable
resource as an organic fertiliser is important for a balanced P supply of agricultural soils and
for reducing nutrient losses to the Baltic Sea. Especially with view to phosphorus, manure
handling needs special attention to ensure a careful use of this limited resource.
A complementary strategy for the utilisation of manure, the maintenance of a sufficient soil
nutrient status and the minimisation of environmental risks is necessary. A promising
strategy is variable-rate application of fertilisers as the nutrient input matches exactly the
nutrient demand. This concept considers the small-scale variability of soil and crop features
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on a single field and transforms this knowledge into algorithms for a variable-rate
application. The small-scale spatial and temporal variation of nitrate in soils has been
assessed by Haneklaus et al. (1998). The content of available nitrogen varies even over
distances shorter than 30 m and between sampling dates. The nitrate contents range from
28 to 100 kg N ha-1 which resulted in variable-rates from 23 to 43 kg N ha-1. Algorithms for a
variable-rate application of mineral multi-nutrient fertiliser have already been developed by
Haneklaus and Schnug (2000). Algorithms for a site-specific input of manure and slurry are
missing so far, but are crucial for a purely demand-driven input of nutrients. The site-specific
fertilisation with manure is demanding as in contrast to manufactured mineral fertilisers
manure is a heterogeneous product because dry matter content, elemental composition and
pH vary considerably.
Generally, variable-rate application requires some essential prerequisites. Firstly, the
acquisition of information on the variability of some soil characteristics important for the
nutrient availability has to be undertaken. Those parameters are on the one hand the actual
available nutrient contents and on the other hand long-term stable features such as soil
texture, organic matter content and geomorphology (Haneklaus and Schnug, 2000).
Secondly, the composition and the short and long-term impact of the fertiliser on the
nutrient availability have to be known for each application date. Additionally, techniques for
the exact and just in time application are necessary. Such techniques will be discussed in this
report.
The aim of the presented report is

to introduce the legal framework of manure application in the countries of the Baltic
Sea region,

to describe the advantages and disadvantages of fertilisation with manure in relation
to mineral fertilisers,

to give an overview about the nutrient composition and amount of slurry in relation
e.g. to animal species and feeding regime, and

to develop algorithms for the variable-rate application of slurry.
The strategies presented in this report focus on slurry (liquid manure) and the
environmentally relevant plant nutrients nitrogen and phosphorus. The presented data and
algorithms are based on actual values and literature data.
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2
Legal framework for manure application
The legal situation for manure application in the countries of the Baltic Sea region is
harmonised with directives of the European Union. Those directives were mostly transferred
to national laws, where, in some cases, the general rules have been tightened. Most rules for
manure application originate from one of the oldest EU environmental programs: the
Council Directive of 12 December 1991 concerning the protection of waters against pollution
caused by nitrates from agricultural sources (91/676/EEC, “Nitrate Directive”). In addition,
also the Directive 2008/1/EC of the European Parliament and of the Council of 15 January
2008 concerning integrated pollution prevention and control (“IPPC Directive”) and the
Directive 2000/60/EC of the European Parliament and of the Council establishing a
framework for the Community action in the field of water policy (“Water Framework
Directive”) have effects on manure application rules, for example on phosphorus losses. As a
consequence of the Nitrate Directive, codes of good agricultural practice have been
developed and have been implemented in national guidelines or even laws. Additionally,
nitrate action programmes have to be developed by the member states. The oldest
framework for protection of the Baltic Sea and preventive measures onshore is the
Convention on the Protection of the Marine Environment of the Baltic Sea Area (Helsinki
Convention).
Table 1 and Table 2 summarise the legal standards for slurry application in the countries of
the Baltic Sea region. The main differences between the countries are the area of the nitrate
vulnerable zones, the maximum application amount following nitrogen or phosphorus and
the regularly updated guidelines in Denmark. Several countries have declared the whole
country as nitrate vulnerable; thus, the application rules are valid for the whole country. In
Latvia, regulations apply for the entire country with stricter rules in nitrate vulnerable zones.
In Sweden, most regulations are only valid in nitrate vulnerable zones and not the entire
country. Most countries adopted the maximum value for manure application from the
Nitrate Directive and fixed it at 170 kg N ha-1 a-1. Only 140 kg N ha-1 a-1 are allowed in
Estonian NVZs and for pig manure in Demark. On the contrary, Sweden regulates the
manure application by a phosphorus limit of 22 kg P ha -1 a-1, which also fulfils the
requirements of the Nitrate Directive. Noteworthy is that mineral fertilisers can be applied in
addition to manure whereby rates are not limited.
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Table 1 Legal frameworks for slurry application in countries of the Baltic Sea region.
Country
Reference
Updates
Denmark
Vejledning om gødsknings- og harmoniregler (Guidelines on regulations
of fertilising and harmony rules), 09.2012
Bekendtgørelse om erhvervsmæssigt dyrehold, husdyrgødning, ensilage
m.v. (Order on commercial animal husbandry, manure and silage),
28.06.2012
Estonia
Veeseadus (Water Act), 11.05.1994, last revision 21.12.2011
Finland
Opas ympäristötuen ehtojen mukaiseen lannoitukseen 2007-2013
(Guide for fertilisation according to Agri-Environmental policy during
2007-2013), 04.2009
Germany Düngeverordnung (Fertilising Ordinance), 27.02.2007, last revision
24.02.2012
Latvia
Noteikumi par ūdens un augsnes aizsardzību no lauksaimnieciskas
darbības izraisītā piesārņojuma ar nitrātiem (Regulations regarding
protection of water and soil from pollution with nitrates caused by
agricultural sources), 18.12.2001, last revision 05.05.2009
Lithuania Lietuvos Respublikos Žemės Ūkio Ministro ir Lietuvos Respublikos
Aplinkos Ministro: Dėl Vandenų apsaugos nuo taršos azoto junginiais iš
žemės ūkio šaltinių reikalavimų patvirtinimo (On the approval of
provisions for the protection of water from pollution caused by nitrogen
compounds from agricultural sources of the Minister of Agriculture and
the Minister of Environment of the Republic of Lithuania), 19.12.2001
Lietuvos Respublikos Žemės Ūkio Ministro: Dėl Geros ūkininkavimo
praktikos reikalavimų (Codes of good agricultural practice of the Minister
of Agriculture of the Republic of Lithuania), 16.07.2004, last revision
04.05.2006
Poland
Ustawa o nawozach i nawozeniu (Fertiliser and Fertilisation Act),
10.07.2007
Rozporządzenie Ministra Rolnictwa i Rozwoju Wsi w sprawie
szczegółowego sposobu stosowania nawozów oraz prowadzenia szkoleń
z zakresu ich stosowania (Ministry of Agriculture Decree on application
of fertilisers and education in fertilisation), 16.04.2008, last revision
25.06.2012
Ustawa Prawo wodne (Water Act), 18.07.2001, last revision 09.02.2012
Sweden
Statens jordbruksverks föreskrifter och allmänna råd om miljöhänsyn i
jordbruket vad avser växtnäring (Swedish Board of Agriculture rules on
environmental concerns in agriculture as regards plant nutrients), 2004,
last revision 22.06.2011
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Table 2 Regulations for slurry application in countries of the Baltic Sea region defined by the legal frameworks listed in Table 1. The overview is restricted to
slurry, application on arable land and without stating all legal exceptions. Some aspects of good agricultural practice like manure working into the soil and
vegetation cover have not been considered.
Country
NVZa
Maximum application
total maximumb
special rules
Animal density Application prohibited
Winter time
Water regime
c
-1
LU ha
• 140 kg N ha-1 a-1
(pigs)
• 170 kg N ha-1 a-1
(cattle)
in certain
areas, P is
restricted by
a maximum
input level in
the feeding
ration
• ≤ 1.4 (pigs)
if > 100 kg N ≤ 2
ha-1 a-1,
application in ≤ 1.5 (NVZ)
two parts
% territory
Denmark
100
Estonia
7.7
170 kg N ha-1 a-1
25 kg P ha-1 a-1
140 kg N ha-1 a-1
(NVZ)
Finland
100
170 kg N ha-1 a-1
• ≤ 1.7 (cattle)
harvest - 01.02.
(winter oilseedrape and grass
until 01.10.)
Other restrictions
Excessive nutrients
on frozen, watersaturated,
flooded or snowcovered soil
• buffer zone to open
water bodies
• regulations for
sloping grounds
• possible further
restrictions (e.g. 0.7 x
LU) in sensible
groundwater-areas
01.11. - 31.03. on frozen, water• buffer zone to open
saturated,
water bodies
flooded or snow• regulations for
covered soil
sloping grounds
• advanced
regulations for NVZ
15.10. - 15.04.
if soil P exceeds 40- • buffer zone to open
50 mg dm-3 soil or 20 water bodies
if not frozen or
mg dm-3 peat
• regulations for
water-saturated:
(highest P class,
sloping grounds
15.11. - 01.04.
depends on texture)
if cattle manure is
the only P source,
application up to 20 t
ha-1 even for high P
classes are allowed
Continued on next page
8
Table 2 (continued)
Germany
100
170 kg N ha-1 a-1
Latvia
13
170 kg N ha-1 a-1
(NVZ)
170 kg N ha-1 a-1
(including mineral
N)
Lithuania 100
Poland
19
170 kg N ha-1 a-1
[25 kg P ha-1 a-1]
01.11. - 31.01.
≤ 1.7 (NVZ)
15.11. - 01.03.
(NVZ)
≤ 1.7
01.12. - 31.03.
01.12. - 28.02.
water bodies
• regulations for
sloping grounds
• Compensation
fertilisation in autumn
only for remaining
straw
water bodies
• regulations for
sloping grounds
• advanced
regulations for NVZ
water bodies
• regulations for
sloping grounds
water bodies
• regulations for
sloping grounds
9
Table 2 (continued)
Sweden
9
22 kg P ha-1 a-1
01.11. - 28.02.
(NVZ)
[170 kg N ha-1 a-1]
01.08. - 30.11.
(NVZ)
(Blekinge,
Skåne, Halland
(all within
NVZ)): only on
growing crops;
special
regulations for
sowing crops
a
nitrate vulnerable zones according to the Nitrate Directive; b farm average; c livestock units
(NVZ)
water bodies (NVZ)
• regulations for
sloping grounds (NVZ)
• if soil P exceeds P-AL
class III, fertilisation
equivalent only to
plant removal
10
3
Advantages and disadvantages of mineral fertilisers and slurry
Manure is a natural organic product, which has been used traditionally for fertilisation.
Manure contains large amounts of organically-bound and medium-term plant-available
nutrients, while the nutrients of partly or fully digested mineral fertilisers are immediately or
on a short term basis plant-available. Differences exist for the availability of phosphorus in
mineral fertilisers: for instance, phosphorus in triple phosphate is water soluble and thus
instantly plant available, whereas phosphorus in rock phosphates is soluble only in strong
acids so that P availability on agricultural soils is marginal at best in acid soils.
The actual N and P utilisation efficiency of different manure types is summarised in Table 3.
The data basis for the values provided is small and it is founded on studies in single
countries; therefore, the standard values are different in the countries of the BSR. In general,
50-70% of the nitrogen is credited as available in the first year with slightly higher values for
pig slurry (Table 3). Only Estonia and Latvia give values (40% and 35%, respectively) for the
phosphorus availability in the first year (Table 3).
Additionally, manure application takes effect also in following years. The not readily
available nutrients will be mineralised with time. Experiments showed that manure
fertilisation according to the nutrient offtake by plants did not alter the content of available
phosphorus in soils (Schnug et al., 2003; Schick et al., 2012). Hence, there is a dynamic
equilibrium between mobilisation of former applied phosphorus forms and newly applied
stable phosphorus forms (Schnug et al., 2003) and phosphorus is considered as entirely plant
available on a long-term application of manure (Sächsische Landesanstalt für Landwirtschaft,
2007; Schneider-Götz et al., 2011). However, the long-term effect is largest in the second
year, but only Estonia and Latvia give explicit nutrient availabilities for the second year
(Table 3). Latvia refers to 10% of total N and total P, while Estonia specifies 0% of total N and
20% of total P. Both do not distinguish between pig or cattle manure (Table 3).
Furthermore, regular manure applications have long-term effects on nutrient supply.
Periodic manure applications cause an accumulation of organic matter, which is visible in
two times higher organic matter contents in soils fertilised with manure for 140 years
compared to ones without fertilisation (Rothamsted Research, 2006). The organic matter
content in soils is even higher (factors 1.2-3.2) after manure applications than after mineral
fertiliser applications shown in many long-term experiments (22-141 years; Edmeades 2003).
Therefore, higher nutrient recoveries can be assumed for application periods longer than
five years than for single applications (Sächsische Landesanstalt für Landwirtschaft, 2007;
Schneider-Götz et al., 2011). Denmark considers that after ten years of regular manure
applications nitrogen availability will be higher for the year of application (Table 3). So far
these results have not been implemented in national regulations for manure application.
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Table 3 Percentages of plant available nutrients in slurry for the year of application and subsequent years. The data according to the EU member states’ action
programmes is taken from European Commission – Directorate General Environment, 2010.
Country
Definition of
available
nutrient
Denmark fertiliser
replacement
value
Estonia
direct effect =
crop utilisation
Finland
indirect
indication:
fertiliser
replacement
value
Germany available nutrient
Latvia
fertiliser
replacement
value
Lithuania available nutrient
Poland
fertiliser
replacement
value
Sweden available nutrient
Part of action Nt
programme
Cattle
st
1 year
%
no
Pt
Pig
Cattle
long-term
st
1 year
long-term
70
10 a
(indirecta)
75
no
50
50
no
-
0%
2nd year
no
no
no
50
50
no
10%
2nd year
no
no
-b
-
60 (spring), no
50 (autumn)
Pig
1 year
long-term
1st year
long-term
10 a
(indirect)
-
-
-
-
0%
2nd year
no
40
20%
2nd year
40
20%
2nd year
-
-
-
-
60
50
no
10%
2nd year
35
10%
2nd year
35
10%
2nd year
-
-
-
-
-
-
60 (spring),
50 (autumn)
no
-
-
-
-
-
st
no
75% of
yes
100% of
yes
residual
residual NH4NH4-N after
N after
c
spreading
spreading
a
The residual fertiliser effect is already incorporated in the 1st year value; b only values for solid manure available; c The NH3 losses after spreading in spring are
presumed to be 10% of NH4-N content for slurry (Swedish Board of Agriculture, 2010).
12
4
Factors influencing the mineral composition of slurry
Several factors influence the mineral composition of slurry in the tanks. These imply animal
type and weight, feedstuff quality and quantity, housing management, storage time and
condition, and water content (Cordovil et al., 2012). Table 4 shows differences in the N and P
content of slurry in relation to animal species and housing system. In general, slurry of cattle
contains more solids and more N and has consequently a higher N:P ratio than pig slurry.
The differences between the housing systems are only minor. Only tie-up housing of dairy
cows and fattening bulls exhibit higher N:P ratios in manure than cubicle housing. By
comparing dairy cows and fattening bulls, it can be stated that slurry of fattening bulls has
higher solid percentages, while slurry of dairy cows contains less N and P (Table 4 & Table 5).
Table 5 shows also the effect of different cattle races on slurry composition. However, the
race has obviously no large influence on manure composition.
Table 4 Variation of slurry composition depending on different housing systems for pigs and cattle.
Data taken from Poulsen, 2012. The values have been calculated by using a large Danish dataset
originated from farmers, feedstuff companies, and controlling authorities (Poulsen, personal
communication).
Housing system
Solids
%
N
kg t
P
N:P
-1
Fattening pigsa
Partly slatted floor (25-50%)
06.6
4.96
1.16
4.3
Fully slatted floor
06.1
4.53
1.15
3.9
Draining + slatted floor (33 + 67%)
06.1
4.63
1.15
4.0
b
Dairy cows
Tie-up housing with floor grating
11.1
6.10
0.91
6.7
Cubicles with solid floor
09.3
5.22
0.83
6.3
Cubicles with slatted floor
09.3
5.33
0.83
6.4
Fattening bullsc
Tie-up housing with floor grating
12.8
6.91
1.14
6.1
Cubicles with solid floor
12.3
7.10
1.30
5.5
Cubicles with slatted floor
12.3
7.31
1.30
5.6
a
Fattening from 32 kg up to 107 kg (+75 kg); b Heavy races, 9265 kg milk animal-1 a-1, 3.38% proteins;
c
Heavy races, 6 months fattening, 220 kg growth.
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Table 5 Effect of cattle races on slurry composition. Data taken from Poulsen, 2012. The values have
been calculated by using a large Danish dataset originated from farmers, feedstuff companies, and
controlling authorities (Poulsen, personal communication).
Race
Solids
%
N
kg t
P
N:P
-1
Dairy cows, cubicles with slatted floor
Heavy racesa
09.3
5.33
0.83
b
Jersey
09.3
5.45
0.88
Fattening bulls, cubicles with slatted floor
Heavy racesc
12.3
7.31
1.30
d
Jersey
12.7
7.60
1.34
a
-1 -1
b
-1 -1
9265 kg milk animal a , 3.38% proteins; 6584 kg milk animal a , 4.13% proteins; c
fattening, 220 kg growth; d 6 months fattening, 183 kg growth.
6.4
6.2
5.6
5.7
6 months
The difference of manure composition at different animal age stages is stated for pigs in
Table 6. For cattle, there is no data available, because the calves do not produce slurry. Due
to the requirements at different age stages, also the housing systems are different. The solid
content as well as the N:P ratio increase by animal age. However, there are distinct
differences for the nutrient composition of slurry at different ages. Caused by higher
nutrient uptake by older and bigger pigs, the N and P contents are higher in slurry of
fattening pigs than of weaners. The P content of slurry of sow with piglets is remarkably
high.
Table 6 Liquid pig manure composition at different growth stages. Data taken from Poulsen, 2012.
The values have been calculated by using a large Danish dataset originated from farmers, feedstuff
companies, and controlling authorities (Poulsen, personal communication).
Age stage
Housing system
Solids
%
N
kg t
P
N:P
-1
Sow with 28.1 pigletsa Individual housing, partly slatted floor
4.5
3.85
2.89
1.3
b
Weaner
Two-climate housing, partly slatted floor 5.0
3.36
0.99
3.4
c
Fattening pig
Partly slatted floor (25-50%)
6.6
4.96
1.16
4.3
a
b
c
per year, piglets up to 7.3 kg; from 7.3 kg up to 32 kg; Fattening from 32 kg up to 107 kg (+75 kg).
The water content of slurry makes it expensive to transport manure over long distances. At
the same time, the mixture of solids and water causes bad flow behaviour and manure solids
that can block the manure spreading machine.
Segregation causes stratification of manure with different nutrient compositions at the top
and the bottom of the tank (Table 7). Though solids sink to the bottom, the nutrient content
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is not necessarily higher at the bottom (Table 7). Cattle slurry contains also organic particles
which tend to float (Derikx et al., 1997)
Table 7 Concentrations of total dissolved solids, nitrogen and phosphorus at different depths for
various manure storage places.
Source and
storage type
Replicates Depth
Cattle,
manure reservoir
1
Dairy cow,
manure lagoon
1
Pig, nursery barn,
deep-pit
2
Solids Nta
Ptb
N:P
Source
00.61
00.11
00.12
09.94
10.07
07.89
00.90
01.00
02.50
04.30
04.20
01.60
01.20
03.10
00.94
00.76
00.59
00.38 00.06
00.39 00.08
03.0
13.6
05.8
03.4
03.5
03.3
05.0
04.6
02.4
01.8
01.6
03.1
03.9
01.9
Goncalves Junior et al., 2006
06.8
05.1
McLaughlin et al., 2012
top
00.4 00.76 00.15
0.5
00.4 00.95 00.19
1.5
00.4 01.21 00.43
bottom 01.1 03.32 03.42
a
b
total nitrogen; total phosphorus; c data derived from figures.
05.2
04.9
02.8
01.0
Lovanh et al., 2009
m
Pig, finishing barn, 2
deep-pit
Pig, hogs,
concrete storage
8
Pig,
manure lagoon
1
Pig,
manure lagoon
1
0.0
0.7
1.3
top
middle
bottom
0.0
0.6
1.2
1.6
0.0
0.6
1.2
1.8
top
middle
bottom
0.0
1.0
%
06.0
04.9
09.4
02.8
03.0
08.0
11.0
07.2
04.0
03.0
05.8
03.2
02.9
02.5
kg t
-1
01.84
01.50
00.69
33.40
35.20
26.20
04.50
04.60
06.00
07.90
06.90
04.90
04.70
05.80
Nova Scotia Department
of Agriculture, 2011
Ndegwa et al., 2002c
Ndegwa et al., 2002c
Campbell et al., 1997
Seasonal trends of manure composition have been reported (Figure 2 & Figure 3).
DeRouchey et al. (2002) analysed several pig slurry lagoons. The N concentrations are higher
in June than October (1.6 versus 1.2 kg N t-1 FM) (DeRouchey et al., 2002). The P
concentrations are higher in June than December (0.29 versus 0.13 kg P t -1 FM) (DeRouchey
et al., 2002). According to DeRouchey et al. (2002), the reasons for higher nutrient contents
in summer are mixing by an elevated number of microorganisms and concentration effects
by higher evaporation and less rain. Animal production phase and chemical stability of the
slurry contribute to the seasonal trend, too. For instance, ammonia releases are affected by
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the surrounding temperature (Sommer, 1997). For a variable rate application of slurry it is
either necessary to produce a homogenous mixture or to analyse the mineral composition in
real-time.
Figure 2 Seasonal trends of nitrogen concentrations in US-American anaerobic pig manure lagoons.
Figure 3 Seasonal trends of phosphorus concentrations in US-American anaerobic pig manure
lagoons.
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Another significant factor influencing the mineral composition of slurry is the feeding
regime. Usually, feedstuff is administered at rates that warrant maximum live weight gain
and which supply the livestock with all essential nutrients. For example, in Germany, the
Gesellschaft für Ernährungsphysiologie (Society of Nutrition Physiology) publishes
recommendations for the energy and nutrition supply, which is based on scientific studies.
Though, guidelines and feeding practices vary from country to country. Table 8 and Table 9
present feed quantity, feed composition and ex-animal manure composition for pigs and
cattle in various countries of the Baltic Sea region. These tables underline the differences of
feed and manure quantity and composition between animals of different ages (see also
Table 6). Differences in ex-animal manure composition between countries are related to
different animal productivities and demand for feedstuff. In detail, the concentrations of N
and P in pig slurry are higher in Sweden than in Denmark. The nutrient concentrations in
dairy cow slurries are difficult to compare, because of differing milk production. The higher
the milk production, the higher the nutrient concentration in the slurry.
Figure 4 and Figure 5 summarise the variation ranges of nitrogen and phosphorus
concentrations in pig and cattle slurries. These variation ranges are displayed for the effects
of different feedings, races, animal ages, housing systems, seasons, and storage depths on
manure composition. The values of the variation range for feeding effects are ex-animal
ones whereas the other variation ranges are based on ex-housing or ex-storage values;
consequently, a loss of nitrogen from ex-animal to storage is visible in Figure 4. Supposedly,
the nitrogen is degassed during storage (e.g. Donham et al., 1977). Animal races and housing
systems tend to have a low effect on the variation of the nitrogen and phosphorus content.
In comparison, animal age and especially the storage depths have a high impact on the
variation of N and P (Figure 4 & Figure 5). The effects of different feedings on slurry
composition are animal specific: dairy cows show a high variation of nitrogen and pigs of
phosphorus concentrations in slurry.
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Table 8 Feeding instructions for pigs in various countries of the Baltic Sea region. (Sources: Denmark: Poulsen, 2012; Finland: MTT Agrifood Research, 2012;
Germany: GfE, 2006 & Berk, personal communication; Germany RAM: Meyer & Berk, personal communication; Latvia: Kārkliņš & Līpenīte, 2008; Sweden: STANK
database & Baky, personal communication).
Country
Animal age / animal
productivity
Days
Weight
Feed
Start
End
kg
Metabolisable Feed content
energy
N
P
MJ d⁻¹
Uptake
N
P
g animal⁻¹ d⁻¹
Digestibility Slurry ex-animal
N
P
N P
Mass
-1
%
kg t
t a-1
Denmark Sows, 28.1 piglets a-1 028
24.0 g FU⁻¹ 6.3 g FU⁻¹ 1315.7 345.4 80
45
6.3 1.4 4.0
Weaner
007.3 032
26.3 g FU⁻¹ 6.4 g FU⁻¹
4.9 1.4 0.1
Fattening pigs
032
107
25.3 g FU⁻¹ 5.5 g FU⁻¹
6.0 1.3 0.5
-1
Finland
Sows, 20 piglets a
7.9 FU d⁻¹ 73.7
22.4 g FU⁻¹ 3.0 g FU⁻¹ 0177.0 023.7
a
Fattening pigs
025
055 1.6 FU d⁻¹ 14.9
24.0 g FU⁻¹ 2.7 g FU⁻¹ 0038.4 004.3
Fattening pigs
055
080 2.4 FU d⁻¹ 22.3
19.2 g FU⁻¹ 2.4 g FU⁻¹ 0046.1 005.8
Fattening pigs
080
120 3.0 FU d⁻¹ 27.9
18.4 g FU⁻¹ 1.9 g FU⁻¹ 0055.2 005.7
-1
Germany Sows, 20 piglets a
6.7 kg d⁻¹ 88.0
25.6 g kg⁻¹ 5.5 g kg⁻¹ 0170.7 036.7 >80 >50
025
Weaner
028 0.7 kg d⁻¹ 08.7
27.2 g kg⁻¹ 5.0 g kg⁻¹ 0017.7 003.3 >80 >50
028
Fattening pigs
028
040 2.5 kg d⁻¹ 32.5
25.6 g kg⁻¹ 5.0 g kg⁻¹ 0064.0 012.5 >80 >50
050
Fattening pigs
040
115
4.3
kg
d⁻¹
55.3
24.0 g kg⁻¹ 4.5 g kg⁻¹ 0102.0 019.1 >80 >50
055
Germany, Sows lactating
26.4 g kg⁻¹ 5.5 g kg⁻¹
>80 >50
b
RAM
Weaner
030
27.2
28.8 g kg⁻¹ 5.5 g kg⁻¹
>80 >50
feed
Fattening pigs
27.2 g kg⁻¹ 5.5 g kg⁻¹
>80 >50
Fattening pigs
22.4 g kg⁻¹ 4.5 g kg⁻¹
>80 >50
Latvia
Sows, 18 piglets a-1
25.9 g kg⁻¹ 5.1 g kg⁻¹
Fattening pigs
020
130
28.6 g kg⁻¹ 6.6 g kg⁻¹
Sweden Fattening pigs
7.0 2.5 0.5
a
-1
-1 b
feed units (Denmark: 12.6 MJ metabolisable energy kg , Finland: 9.3 MJ net energy kg ); Feed with reduced nitrogen and phosphorus contents. The given
values are maximum values for such feed.
18
Table 9 Feeding instructions for cattle in various countries of the Baltic Sea region. (Sources: Denmark: Poulsen, 2012; Finland: MTT Agrifood Research, 2012;
Germany: Landwirtschaftskammer Schleswig-Holstein, 2012; Latvia: Kārkliņš & Līpenīte, 2008; Sweden: STANK database & Baky, personal communication).
Country
Denmark
Finland
Germany
Animal age /
animal productivity
Dairy cows, heavy race,
9265 l milk
Dairy cows, Jersey,
6584 l milk
Fattening bulls, heavy race
Fattening bulls, Jersey
Dairy cows, 40 kg milk d-1,
3% protein
Growing cattle
Growing cattle
Growing cattle
Growing cattle
Growing cattle
Growing cattle
Dairy cows, 30 kg milk d-1,
4.0% fat, 3.4% protein
Growing cattle
Growing cattle
Growing cattle
Growing cattle
Growing cattle
Days
Weight
Start End
kg
Feed
kg d⁻¹
Metabolisable Feed content
energy
N
MJ d⁻¹
P
Uptake
N
P
g animal⁻¹ d⁻¹
Slurry ex-animal
N
P
Mass
-1
kg t
t a-1
365
18.2
27.7 g FU⁻¹ a
4.3 g FU⁻¹
526.6
80.9
6.5
0.9
21.8
365
15.0
27.7 g FU⁻¹
4.3 g FU⁻¹
448.0
68.8
6.6
1.0
18.1
23.2 g FU⁻¹
23.2 g FU⁻¹
4.2 g FU⁻¹
4.2 g FU⁻¹
29.4
23.1
87.0
8.6
8.5
1.3
1.3
02.8
02.2
183
183
25.3
272.0
162.3
127.8
371.8
150
250
350
450
550
650
650
20.0
043.0
058.0
076.0
092.0
107.0
121.0
136.2
051.7
058.6
009.6
012.8
016.0
019.2
480.0
16.0
17.0
19.0
20.0
22.0
24.0
71.0
250
350
450
550
650
04.5
06.3
07.5
08.3
10.5
044.3
060.8
077.5
094.5
111.9
089.6
110.4
140.8
171.2
201.6
15.0
17.0
20.0
22.0
27.0
650
650
100
150
250
350
450
550
650
150
250
350
450
550
19
Table 9 (continued)
Latvia
Dairy cows, 7000 kg milk
600
600
07.6
Fattening bulls
365
150
450
19.2
Sweden
Dairy cow, 6000 l milk
a
feed units (Denmark: 12.6 MJ metabolisable energy kg-1, Finland: 9.3 MJ net energy kg-1).
19.1 g kg⁻¹
23.7 g kg⁻¹
3.9 g kg⁻¹
3.6 g kg⁻¹
5.7
6.3
7.4
8.1
0.9
0.9
0.9
1.1
17.5
18.5
18.8
18.0
20
Figure 4 Variation range of nitrogen contents in slurry of fattening pigs, bulls, and dairy cows
depending on feeding (see Table 8 and Table 9), races (see Table 4), animal age (see Table 6), housing
systems (see Table 4), season (see Figure 4, only data from DeRouchey et al., 2002), and storage
depth (lagoon, deep-pit, and tank; see Table 7). The boxes give the minimum and maximum value and
if more than two values are available also the median.
Figure 5 Variation range of phosphorus contents in slurry of fattening pigs, bulls, and dairy cows
depending on feeding (see Table 8 and Table 9), races (see Table 4), animal age (see Table 6), housing
systems (see Table 4), season (see Figure 5, only data from DeRouchey et al., 2002), and storage
depth (lagoon, deep-pit, and tank; see Table 7). The boxes give the minimum and maximum value and
if more than two values are available also the median.
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One putative problem for the use of manure is the existence of contaminants in manure.
These can either be heavy metals like copper (from pig feed), or organic pollutants like
veterinary medicals (Finck, 1992).
Summarising the effects of different factors on mineral composition of slurry it can be stated
that

The N content in ex-housing slurry increases in the order pigs (median 4.6 kg N t-1 FM)
< dairy cows (median 5.3 kg N t-1 FM) < bulls (median 7.1 kg N t-1 FM) by about 15%
and 33%, respectively (Table 4). Thus, the N concentration varies with animal species
by 153%.

The P content in ex-housing slurry increases in the order dairy cows (median 0.8 kg P
t-1 FM) < pigs (1.2 kg P t-1 FM) < bulls (1.3 kg P t-1 FM) by about 39% and 13%,
respectively (Table 4). Thus, the P concentration varies with animal species by 157%.

Animal race and housing system have only a low impact on ex-housing slurry
composition (Table 4 & Table 5). The largest difference has the P concentration in
slurries of heavy and Jersey dairy cows (6%).

N and P excretion increases with age from weaners (3.3 kg N t-1 FM and 1.0 kg P t-1 FM
in ex-housing slurry) to fattening pigs (5.0 kg N t-1 FM and 1.2 kg P t-1 FM in ex-housing
slurry) by about 48% and 17%, respectively (Table 6).

The effect of higher feeding supplements to pigs is visible in 17% higher N (7.0 kg N t-1
FM) and 92% higher P (2.5 kg P t-1 FM) concentrations in slurry from Sweden than in
Danish slurry (6.0 kg N t-1 FM, 1.3 kg P t-1 FM) (Table 8).

The N and P contents have a broad range at different storage depths and varying
storage systems. The N and P concentrations vary by 9191% (0.4-35.2 kg N t-1 FM) and
by 17985% (0.1-10.1 kg P t-1 FM), respectively (Table 7).

Also the season has an influence on ex-storage slurry composition. The N and P
concentrations vary by 142% (1.2-1.6 kg N t-1 FM) and by 219% (0.1-0.3 kg P t-1 FM),
respectively (Figure 4 & Figure 5).
Usually, species, race, housing system and feeding regime are constant at each farm if the
management does not change. Conn et al. (2007) found a high variation of slurry
compositions between farms, but in general the composition of slurry of individual farms
was consistent over time. The largest effects on slurry composition have the factors storage
depth, the season and the animal age. However, the variation due to storage depth should
be smaller than stated above, because the farmer uses only one type of storage and the
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slurry is often agitated in the storage tank. Seasonal variation affects the slurry composition
most pronounced. In the warmer season (March-October), when slurry will be used, the pig
slurry composition varies by 42% (N) and 35% (P). The effect of animal age on pig slurry
composition is in the same order (N: 48%, P: 17%). A summation of those variations is
difficult, because these are ex-housing and ex-storage values and ex-storage comprises exhousing effects. Ndegwa et al. (2002) studied the combined effect of pig age and storage
depth on slurry composition: N varies by 76% and P by 378% (Table 7).
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5
5.1
Variable-rate slurry application
Prerequisites
In the previous section, factors influencing the mineral composition of slurry, relevant
parameters which cause variation of the mineral composition and water content of slurry
were listed. The coefficient of variation (CV) was determined for mineral nutrients in slurry
from different animals in extended surveys (e.g. Derikx et al., 1997; Sharpley and Moyer,
2000). The results of these studies showed similar results and the CV for total P varied
between 21.0 and 75.8% in cattle slurry (Overcash et al., 1983 cited in Nath, 1992; Derikx et
al., 1997; Salazar et al., 2007; Hjorth et al., 2010), 5.8 and 87.8% in pig slurry (Derikx et al.,
1997; Sharpley and Moyer, 2000; Sánchez and González, 2005; Hjorth et al., 2010), and 21.0
and 75.8% in poultry slurry (Overcash et al., 1983 cited in Nath, 1992; Derikx et al., 1997).
The reported CV vary over a wide range, but the lower CV are more regularly found in
studies of temporal changes of slurry composition within a farm and not in studies with
slurries from different farms. With view to variable rate application of slurry, the lower CV,
especially of pig slurry, are suitable for an exact application of slurry as the range of variation
is moderate. For instance, at a rate of 22 kg P ha-1 a-1, with pig slurry 21-23 kg P ha-1 a-1
would be applied (Sharpley and Moyer, 2000). In contrast, with dairy cow and laying hens
slurry the amount of P would vary between 18-26 kg P ha-1 a-1 and 17-27 kg P ha-1 a-1,
respectively (Derikx et al., 1997; Hjorth et al., 2010). In contrast, the application of slurries
with a higher CV is unlikely to result in a match of P demand and P rate. For example, the
amount of P in pig slurry can vary from 3 to 41 kg P ha-1 a-1 (Sánchez and González, 2005).
Here, technological processing is required, for example by separating of slurry into solids and
liquids together with homogenisation of the product (see section “Strategies for manure
production”).
Another important aspect of variable rate application of slurry is related to the legal
framework for manure application (see section “Legal framework for manure application”).
At the moment, application rates follow the N demand with rates of up to 170 kg N ha-1 a-1.
This means that together with 170 kg N ha-1 a-1, on average 27 kg P ha-1 a-1 (dairy cow slurry:
N:P ratio 6.4:1, Table 4), 43 kg P ha-1 a-1 (pig slurry: N:P ratio 4:1, Table 4) and 49 kg P ha-1 a-1
(poultry slurry: N:P ratio 3.5:1, Derikx et al., 1997) will be applied. With a view to a
sustainable use of the finite resource P it will be necessary to base the maximum manure
rate on the amount of P applied. This would mean that with 22 kg P ha -1 a-1, on an average
141, 88 and 77 kg N ha-1 a-1 would be applied with dairy cow, pig and poultry slurry. Such
procedure would enforce the need for alternative uses and marketing of slurry.
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In the following sections, procedures for variable rate application of slurry have been
summarized which assume a variation of the mineral content that does not conflict with
original purpose of merging P demand and P rate.
5.2
Online-Measurement of manure composition
Slurry is a heterogeneous mixture, which composition varies over time and only if the range
of variation is acceptable, variable rate input is recommended (see above). Still it is advisable
to measure the manure composition before application in order to determine changes of
nutrient loads. For variable-rate application, changes in the nutrient content of slurry are
registered preferably on-line. Modern spreading machines automatically control slurry
application on a volumetric basis so that nutrient output can be adjusted (Saeys et al., 2008).
A relatively basic instrument for manure analysis is a hydrometer measuring the specific
gravity of slurry. This is also called slurry meter (Tunney et al., 1985). Those hydrometers are
calibrated to the solid concentration, which is in turn related to nutrient contents. Nutrient
regressions have been presented e.g. by Piccinini & Bortone (1991) and Zhu et al. (2003).
However, the slurry has to be mixed before measuring and the density measurements are
restricted to a maximum solid content of 8% dry matter (DM) for pigs and of 6% DM for
cattle, respectively (Tunney et al., 1985). Alternatively, the solid content can be measured
ultrasonically (Scotford et al., 1998, Chien et al., 2000). This method can determine solid
contents up to 40%, but an important disadvantage is that air bubbles distort the
measurement.
A similar method is to measure the electrical conductivity by electrodes and to correlate it
with the nutrient content. This approach worked for N, but failed for P, as the P content
correlates stronger with the content of solids (Provolo & Martinez-Suller 2007). To overcome
this problem, electrodes for electrical conductivity could be linked with devices for
measuring the solids (Scotford et al., 1998).
A direct method for nutrient measurements is the use of ion-sensitive electrodes. Ready-touse ion-sensitive electrodes for N and K have been presented by the machinery company
Wienhoff (Bawinkel, Germany). They stated the precision of the measurement with 90%
(Wienhoff, 2010). Scotford et al. (1999) introduced the combined use of several sensors like
ion-sensitive electrodes, pH electrode and electrical conductivity measurements. However,
such expensive equipment is very rarely used by farmers.
Infra-red spectroscopy has also the capability to determine all nutrients simultaneously. It is
an indirect method, which uses near infra-red spectra and a calibration model to predict
nutrient contents. Yet, only preliminary studies for the feasibility of infra-red spectroscopy
for nutrient determination in slurry have been conducted (e.g. Millmier et al., 2000;
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Zimmermann et al., 2008). The machinery company Zunhammer (Traunreut, Germany)
offers a slurry tanker with near infra-red sensor for the on-the-go measurement of N
concentration (prediction error <10%, Zunhammer, 2011). The P and K output is as well
registered and geo-coded.
Overall, it can be summarised that devices for online measurements of nutrient contents in
manure exist, but these instruments need validation of applicability on production fields.
5.3
Strategies for manure production
As it was already shown, manure composition varies in relation to animal feeding and
storage techniques. Feeding strategies can reduce protein or phosphorus contents in the
feed, which will result in manure with less N or P. For example, the so-called RAM feed
(German: Rohprotein-angepasstes Mischfutter = feed mixture with adjusted raw protein
content) in Germany is an approach to reduce N and P excretion. The reduction of N and P
whilst warranting a sufficient nutrient supply of the animals is achieved by using only
necessary amino acids and easily digestible phosphorus forms. Similar approaches are used
in Denmark, where the nutrients concentrations in slurry are lower than in Swedish slurry.
A low level approach to reduce nitrogen losses from slurry is to cover the storage tank. In
addition, slurry can be acidified to prevent ammonia degassing. Further attempts to prevent
not only nutrient reduction, but also to allow a better handling and energy usage include
techniques like liquid and solid separation, anaerobic digestion and thermal gasification.
Mechanical separation of manure liquids and solids can result in relatively N-rich liquids and
very P-rich solids (e.g. Møller et al., 2000; Hjorth et al., 2010). Table 10 gives the nutrient
variation in solid and liquid fractions after mechanical separation of dairy cow and pig
slurries. The N contents in both fractions vary by 140-160%, whether or not it originated
from dairy cows or pigs. The variation of P concentrations is a little bit higher (about 200%
variation), only the P concentration in dairy cows liquid fraction varies by 500%. Those
separated fractions can be applied separately on the field to fulfil either N or P demands.
Anaerobic digestion and thermal gasification are mainly used for energy purposes, but
especially gasification can supply N-free ashes for fertilisation, because most N is converted
to gaseous N2 or NOx (Prapaspongsa et al., 2010; Kuligowski & Luostarinen, 2011). The total
P content is relatively high in those ashes, but the availability for crops is limited (Kuligowski,
2009; Kuligowski & Luostarinen, 2011).
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Table 10 Nitrogen and phosphorus content in solid and liquid fractions of separated manure
(Denmark). Mean, minimum, and maximum values are given for five different separating techniques
(Møller et al., 2000).
Animal
Dairy cows
Pigs
5.4
Mean
Minimum
Maximum
Mean
Minimum
Maximum
Solid fraction
N
P
-1
gl
4.72
3.80
5.20
5.02
4.00
6.40
1.32
0.90
1.80
2.76
1.80
3.50
N:P
Liquid fraction
N
P
-1
gl
N:P
3.6
4.2
2.9
1.8
2.2
1.8
3.62
2.80
4.50
3.96
3.00
4.40
05.7
14.0
04.5
03.1
03.8
02.6
0.64
0.20
1.00
1.28
0.80
1.70
Additional application of mineral fertilisers
It is important that manure applications will not lead to an oversupply with a nutrient so that
a combination of manure und mineral fertilisers might prove to be suited best to adjust the
nutrient input to the actual crop demand.
Usually the planning of fertiliser input is carried out for the entire crop rotation so that the
nutrient input should be balanced after this time period. This approach increases the
flexibility for a variable-rate input of slurry.
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6
Algorithms for the variable-rate application of slurry
6.1
Prerequisites
Once the soil content of each nutrient and demand of each crop in the rotation has been
assessed, a strategy for the variable-rate application of manure can be calculated. For
developing algorithms for variable-rate application of slurry the following conditions are
obligatory:

An existing N, P, K demand as otherwise manure applications would yield an
undesired nutrient surplus; in case of micro-nutrients, changes in the soil nutrient
status should be monitored.

Spatial information about the site-specific N demand which can be assessed for
instance on basis of geomorphological parameters or changes in the organic matter
and clay content of soils (Haneklaus and Schnug, 2006).

For medium-term variable nutrients such as P and K digital soil maps need to be
established and for recording temporal changes so-called monitor pedo cells need to
be defined (Haneklaus et al, 2000; Panten et al., 2002).

Geo-coded yield monitoring is employed to assess the spatial variation of nutrient
offtakes within the crop rotation.
In addition, the following assumptions and simplifications of the general set-up for defining
the algorithms have been made:
6.2

Digital fertiliser maps are designed for the entire nutrient demand irrespective
whether rates are split in several applications.

Algorithms for N and P have been developed for slurry as it is the prevailing form of
farmyard residues.
Combined application of slurry and single-nutrient mineral fertiliser
Slurry of fattening pigs, fattening bulls and dairy cows exhibit median N:P ratios of about 4:1,
5.6:1, and 6.4:1, respectively (Table 4). Although these are ex-housing slurry values, it can be
assumed that ex-storage slurry nutrient ratios are in the same order if N degassing is
restricted. All slurries are dominated by N, whereas the P proportion is low. Due to the high
water content, nutrient contents relative to the fresh weight are very low. Therefore, high
volumes have to be applied for a reasonable fertilisation.
If fertilisation with manure is done according to the Nitrate Directive, which allows
170 kg N ha-1, the amount of applied phosphorus is regularly too high and leads to
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environmental risks (see above). For example, with pig slurry and using the N limit,
43 kg P ha-1 are applied. According to the German fertilising guide based on the classification
of soil test P (Table 11; Kerschberger et al., 1997; Sächsische Landesanstalt für
Landwirtschaft, 2007), this fits for the two classes with P undersupply (classes A and B), but
not for the other three classes.
Table 11 Soil test P classification and P fertiliser recommendations for Germany (Kerschberger et al.,
1997; Sächsische Landesanstalt für Landwirtschaft, 2007).
STPa class
Plant-available P (PCALb)
mg P kg-1 soil
Fertiliser recommendationc
kg P ha-1 a-1
A
≤ 20
45 – 60
B
20 – 45
30 – 45
C
45 – 90
20 – 30
D
90 – 150
0 – 15
E
≥ 150
0
a
b
soil test P; plant-available P in soil determined after calcium lactate extraction; c recommendation
for a crop rotation with an annual offtake of 25 kg P ha-1 a-1.
Though, variable rates of manure application need to follow the prognosed P offtake by
harvest products and the current soil P status to ensure an optimum level of productivity
(Haneklaus et al., 1996). The input of other nutrients by slurry will always have to be a
multiple of the P rate (Haneklaus and Schnug, 2000). This will not lead to a balanced input of
all nutrients and a discrepancy between the actual demand and applied rates (Figure 1).
Therefore, an optimal status of all nutrients can be achieved by using additional singlenutrient fertilisers. They can either be applied together with the slurry or by a second
application in the same year.
The following examples of a combined application of slurry and mineral fertilisers are dealing
with the situation in Germany. For this purpose, the information of soil phosphorus status
and fertiliser recommendations given in Table 11, the typical nutrient offtake of crops given
in Table 12, and the nutrient availability of Table 3 are used. Field areas with a supply in class
D and E, receive no manure as the status is already too high. Hence, only soils with an
optimum P status (class C) and P deficiency (class A and B) will receive manure. In class C,
manure replaces P offtake of the crop (see Table 12). Soils in class A and B receive higher
amounts of manure. In class A and B, 25 and 10 kg P ha-1 a-1 were applied in addition to P
offtake, respectively (see Table 11). The calculations used the data of fattening pig slurry,
dairy cow slurry and pig slurry solid fraction given in Table 4 and Table 10 (data from
Denmark). The slurry of fattening bulls has a N:P ratio close to dairy cow slurry and was,
therefore, not used for calculations. Accordingly, most slurry fractions after liquid-solid
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separation have N:P ratios close to the slurries, only pig slurry solid fraction was used for
calculations, because this fraction has a low average N:P ratio of 1.8:1 (Table 10).
Table 12 Yield, nutrient content and nutrient offtake of different crops in Germany. Data from
Sächsische Landesanstalt für Landwirtschaft (2007), DüV (2012) and Agravis (2013).
Crop
Product
Yield
-1
Wheat
Barley
Rye
Silage maize
Rapeseed
Sugar beet
Potatoes
Grain
Plant residue
Grain
Plant residue
Grain
Plant residue
Total
Seeds
Plant residue
Beet
Plant residue
Tuber
Plant residue
N
P
N
-1
t ha
kg t
09.0
07.6
07.0
06.6
08.0
08.0
47.5
04.0
06.4
60.0
38.7
45.0
13.4
22.1
05.0
16.5
05.0
15.1
05.0
03.8
33.5
07.0
01.8
04.0
03.5
02.0
P
N:P
31.5
09.9
24.5
08.6
28.0
10.3
33.3
31.2
10.9
24.0
19.3
27.0
02.7
06.3
03.8
04.7
03.8
04.3
03.8
05.4
04.3
04.1
04.5
08.0
05.8
10.0
-1
kg ha
3.5
1.3
3.5
1.3
3.5
1.3
0.7
7.8
1.7
0.4
0.5
0.6
0.2
198.9
038.0
115.5
033.0
120.8
039.8
180.5
134.0
044.8
108.0
154.6
157.5
026.8
Table 13 presents the calculations for application of pig slurry and mineral N fertiliser on a
soil with an optimum P status. The calculation steps can be summarised as follows
1) amount of applied slurry P = P fertiliser recommendation
2) amount of applied N = amount of applied slurry N + amount of applied mineral fertiliser N
with
2.1) amount of applied slurry N = P amount x N:P ratio
2.2) amount of applied mineral fertiliser N = N fertiliser recommendation – plantavailable N from slurry – additional N delivery from soil
The first equation contains the assumption that all applied slurry P can be considered as
plant-available if the site is regularly fertilised with manure. This P consists of directly
available P and additional delivery by mineralisation of soil organic matter, older manure
and crop residues.
With view to N, 60% of pig slurry N and 50% of cattle slurry N are calculated as being plant
available within the year of application so that this value needs to be subtracted from the
entire N demand (equation 2.2). These presumed shares of available N seem too low as
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higher values for Denmark and Sweden (Table 3) and an experimentation with sugar beet
revealed (Haneklaus et al., 1997); in these experiments N utilisation was as high as 83% in
the first year. Mineral N fertilisers are completely plant-available within a year. Additionally,
mineralisation of soil organic matter, older manure and crop residues take place, which
enhances the amount of plant-available N. This additional delivery can be variable due to
weather conditions, soil organic matter content, preceding crop, cultivation management,
and former manure applications (Sächsische Landesanstalt für Landwirtschaft, 2007). At
maximum, only 40 kg N ha-1 a-1 are considered for fertiliser planning in Germany (Sächsische
Landesanstalt für Landwirtschaft, 2007) which does not reflect the true variation in the field.
For simplifying calculations, this value was assumed.
Consequently, the fertiliser planning was done in accordance to plant-available N, but more
N is applied in stable form within slurry, which causes a mismatch of plant offtake of
available N and total N delivery (slurry, mineral fertiliser, additional delivery). Negative
values occur when the mineralisation (40 kg N ha-1 a-1) is larger than the difference between
applied slurry N and available slurry N. The N surplus either accumulates in the soil organic
matter pool or enters the environment. These consequences can be attenuated by
compensation within a suitable crop rotation or by a lower mineral N application.
Table 14-Table 19 presents the calculations for other conditions (pig slurry, dairy cow slurry,
pig slurry solid fraction, soils with optimum and undersupplied P status). However, only
Table 18 and Table 19 (both pig slurry solid fraction) are calculated in the same manner as
Table 13.
The conditions presented in Table 14-Table 17 require a different calculation of the fertiliser
plan. If the calculation is done like before, either the legal limit of 170 kg N ha-1 a-1 by
manure application or the plants N demand is exceeded. Therefore, the calculation does still
follow the plants P demand, but firstly the slurry rate is aligned with plants N demand and
secondly an additional mineral P fertiliser rate is calculated. It can be summarised as follows
1) amount of applied N = amount of applied slurry N + amount of applied mineral fertiliser N
with
1.1) amount of applied slurry N = N fertilising recommendation – additional N delivery
1.2) amount of applied mineral fertiliser N = N offtake by crop – plant-available N of
slurry – additional N delivery
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2) amount of applied slurry P = amount of applied slurry P + amount of applied mineral
fertiliser P
with
2.1) amount of applied slurry P = N amount / N:P ratio
2.2) amount of applied mineral fertiliser P = fertilising recommendation – slurry P
As the amount of applied N is calculated firstly, the differences of N rates between the tables
with varying conditions are only based on the slightly different shares of available N in pig
and dairy cow slurry. The slurry P rates are controlled by fertiliser recommendations and the
N:P ratio of slurry.
By using the calculated N rates and the N concentrations in slurry and solid fraction given in
Table 4 and Table 10, the manure volumes which have to be applied are about 14.7-34.3 t
ha-1 for pig slurry, 12.8-29.8 t ha-1 for dairy cow slurry, and 8.6-21.0 t ha-1 for pig slurry solid
fraction.
Pigs are producing 1.8 and dairy cows 24.3 tons of slurry per animal and year (Poulsen, 2012)
or 11.5 and 24.3 tons of slurry per livestock unit (LU; Thüringer Landesanstalt für
Landwirtschaft, 2013), respectively. By dividing the above stated necessary amount of slurry
per hectare by the tons of slurry per livestock unit, acceptable numbers of livestock densities
for complete slurry application to fields are calculated. The numbers of livestock units per
hectare for using the slurry completely as fertiliser range from 1.3 to 3.0 for pigs and from
0.5 to 1.2 for cows. Most areas in Germany have pig densities below 1 LU ha -1 (Deutsches
Maiskomittee, 2013b); hence, not enough manure for the presented rates is produced in
these regions. Some German regions have livestock densities of about 2 LU ha-1 or even
above (Deutsches Maiskomittee, 2013b); there the livestock densities could be too high for a
complete application of all slurry onto the fields. Then, the farmers have only the option to
use the manure in a different way; this should lastly result in nutrient export into regions
with nutrient deficiency. The high demand of 3.0 pig LU ha-1 for correct fertilisation is
necessary when the soils have P deficiency. Supposedly, these are actual regions which have
a low livestock density. Hence, an import of manure or manure products seems necessary.
For dairy cows, similar trends can be observed. However, milk production is more evenly
distributed across Germany than pig production and the livestock density is more depending
on available land, especially grass fields (Bäurle & Tamásy, 2012; Deutsches Maiskomittee,
2013a). Thus, the dairy cow density at the North Sea coastline (Bäurle & Tamásy, 2012: 0.50.9 LU ha-1), as one main production area, fits into the range of 0.5-1.2 LU ha-1 necessary for
the presented rates.
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Table 13 Algorithms for variable-rate fertiliser application with pig slurry (N:P = 4:1; Table 4) and additional mineral nitrogen fertiliser in Germany. The
fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class C (= P offtake by crop; Table 11).
Limitations by excess of soil nitrogen are not considered. All values are given in kg ha-1 a-1.
Crop
PSla =
P offtake
by crop
NSlb =
multiple (N:P
ratio) of P rate
NSl-avlc =
available N of NSl
Norgd =
NSl-avl plus N from
additional delivery
NMFe =
N offtake by crop
minus Norg
N surplusf =
NSl plus NMF minus
Norg offtake by crop
Wheat
31.5
31.5 x 4 = 126.0
126.0 x 0.6 = 75.6
75.6 + 40 = 115.6
198.9 − 115.6 = 83.3
(126.0 + 83.3) − 198.9 = 10.4
Barley
24.5
24.5 x 4 = 98.0
98.0 x 0.6 = 58.8
58.8 + 40 = 98.8
115.5 − 98.8 = 16.7
(98.0 + 16.7) − 115.5 = -0.8
Rye
28.0
28.0 x 4 = 112.0
112.0 x 0.6 = 67.2
67.2 + 40 = 107.2
120.8 − 107.2 = 13.6
(112.0 + 13.6) − 120.8 = 4.8
Silage maize 33.3
33.3 x 4 = 133.0
133.0 x 0.6 = 79.8
79.8 + 40 = 119.8
180.5 − 119.8 = 60.7
(133.0 + 60.7) − 180.5 = 13.2
Rapeseed
31.2
31.2 x 4 = 124.8
124.8 x 0.6 = 74.9
74.9 + 40 = 114.9
134.0 − 114.9 = 19.1
(124.8 + 19.1) − 134.0 = 9.9
Sugar beet
24.0
24.0 x 4 = 96.0
96.0 x 0.6 = 57.6
57.6 + 40 = 97.6
108.0 − 97.6 = 10.4
(96.0 + 10.4) − 108.0 = -1.6
Potatoes
27.0
27.0 x 4 = 108.0
108.0 x 0.6 = 64.8
64.8 + 40 = 104.8
157.5 − 104.8 = 52.7
(108.0 + 52.7) − 157.5 = 3.2
a
b
c
d
PSl = phosphorus applied with slurry; NSL = nitrogen applied with slurry; NSl-avl = plant available nitrogen in slurry; Norg = nitrogen from organic sources:
plant available nitrogen in slurry plus additional delivery from soil and preceding crop residues. 40 kg N ha -1 a-1 is the maximum value which can be taken into
account (Sächsische Landesanstalt für Landwirtschaft, 2007); e NMF = nitrogen applied with additional mineral fertiliser; f mismatch of plant offtake of available
N for optimum yield and total N delivery (slurry, mineral fertiliser, additional delivery).
33
Table 14 Algorithms for variable-rate fertiliser application with pig slurry (N:P = 4:1; Table 4) and additional mineral nitrogen and phosphorus fertiliser in
Germany. The fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class B (= P offtake by crop
plus 25 kg P ha-1 a-1; Table 11). In this case, P fertilisation by slurry leads to N application above the legal limit of 170 kg N ha-1 a-1 or above the plants N
demands; hence, the slurry application follows the plants N demand and missing P is applied by mineral fertiliser. Limitations by excess of soil nitrogen are not
considered. All values are given in kg ha-1 a-1.
Crop
NSLa =
N offtake by crop
minus N from
additional delivery
PSlb =
multiple (N:P
ratio) of N rate
PMFc =
P offtake by crop
minus PSL
NSl-avld =
available N of NSl
Norge =
NSl-avl plus N from
subsequent
delivery
NMFf =
N offtake by crop
minus Norg (N
Wheat
198.9 − 40. = 158.9
158.9 / 4 = 39.7
41.5 − 39.7 = 1.8
158.9 x 0.6 = 95.3
95.3 + 40.0 = 135.3
198.9 − 135.3 = 63.6
N surplusg =
NSl plus NMF
minus Norg
offtake by crop
(158.9 + 63.6) −
198.9 = 23.6
Barley
115.5 − 40. = 75.5
75.5 / 4 = 18.9
34.5 − 18.9 = 15.6 75.5 x 0.6 = 45.3
45.3 + 40.0 = 85.3
115.5 − 85.3 = 30.2
(75.5 + 30.2) −
115.5 = -9.8
Rye
120.8 − 40. = 80.8
80.8 / 4 = 20.2
38.0 − 20.2 = 17.8 80.8 x 0.6 = 48.5
48.5 + 40.0 = 88.5
120.8 − 88.5 = 32.3
(80.8 + 32.3) −
120.8 = -7.7
Silage maize 180.5 − 40. = 140.5 140.5 / 4 = 35.1
43.3 − 35.1 = 8.1
140.5 x 0.6 = 84.3 84.3 + 40.0 = 124.3 180.5 − 124.3 = 56.2 (140.5 + 56.2) −
180.5 = 16.2
Rapeseed
134.0 − 40. = 94.0
94.0 / 4 = 23.5
41.2 − 23.5 = 17.7 94.0 x 0.6 = 56.4
56.4 + 40.0 = 96.4
134.0 − 96.4 = 37.6
(94.0 + 37.6) −
134.0 = -2.4
Sugar beet
108.0 − 40. = 68.0
68.0 / 4 = 17.0
34.0 − 17.0 = 17.0 68.0 x 0.6 = 40.8
40.8 + 40.0 = 80.8
108.0 − 80.8 = 27.2
(68.0 + 27.2) −
108.0 = -12.8
Potatoes
157.5 − 40. = 117.5 117.5 / 4 = 29.4
37.0 − 29.4 = 7.6
117.5 x 0.6 = 70.5 70.5 + 40.0 = 110.5 157.5 − 110.5 = 47.0 (117.5 + 47.0) −
157.5 = 7.0
a
b
c
d
NSL = nitrogen applied with slurry; PSl = phosphorus applied with slurry; PMF = phosphorus applied with additional mineral fertiliser; NSl-avl = plant available
nitrogen in slurry; e Norg = nitrogen from organic sources: plant available nitrogen in slurry plus additional delivery from soil and preceding crop residues. 40 kg
N ha-1 a-1 is the maximum value which can be taken into account (Sächsische Landesanstalt für Landwirtschaft, 2007); f NMF = nitrogen applied with additional
mineral fertiliser; g mismatch of plant offtake for optimum yield and N delivery (slurry, mineral fertiliser, additional delivery).
34
Table 15 Algorithms for variable-rate fertiliser application with pig slurry (N:P = 4:1; Table 4) and additional mineral nitrogen and phosphorus fertiliser in
Germany. The fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class A (= P offtake by crop
plus 25 kg P ha-1 a-1; Table 11). In this case, P fertilisation by slurry leads to N application above the legal limit of 170 kg N ha-1 a-1 or above the plants N
Crop
NSLa =
N offtake by crop
minus N from
additional delivery
PSlb =
multiple (N:P
ratio) of N rate
PMFc =
P offtake by crop
minus PSL
NSl-avld =
available N of NSl
Norge =
NSl-avl plus N from
subsequent
delivery
NMFf =
N offtake by crop
minus Norg (N
Wheat
198.9 − 40. = 158.9
158.9 / 4 = 39.7
56.5 − 39.7 = 16.8
158.9 x 0.6 = 95.3
95.3 + 40.0 = 135.3
198.9 − 135.3 = 63.6
N surplusg =
NSl plus NMF
minus Norg
offtake by crop
(158.9 + 63.6) −
198.9 = 23.6
Barley
115.5 − 40. = 75.5
75.5 / 4 = 18.9
49.5 − 18.9 = 30.6 75.5 x 0.6 = 45.3
45.3 + 40.0 = 85.3
115.5 − 85.3 = 30.2
(75.5 + 30.2) −
115.5 = -9.8
Rye
120.8 − 40. = 80.8
80.8 / 4 = 20.2
53.0 − 20.2 = 32.8 80.8 x 0.6 = 48.5
48.5 + 40.0 = 88.5
120.8 − 88.5 = 32.3
(80.8 + 32.3) −
120.8 = -7.7
Silage maize 180.5 − 40. = 140.5 140.5 / 4 = 35.1
58.3 − 35.1 = 23.1 140.5 x 0.6 = 84.3 84.3 + 40.0 = 124.3 180.5 − 124.3 = 56.2 (140.5 + 56.2) −
180.5 = 16.2
Rapeseed
134.0 − 40. = 94.0
94.0 / 4 = 23.5
56.2 − 23.5 = 32.7 94.0 x 0.6 = 56.4
56.4 + 40.0 = 96.4
134.0 − 96.4 = 37.6
(94.0 + 37.6) −
134.0 = -2.4
Sugar beet
108.0 − 40. = 68.0
68.0 / 4 = 17.0
49.0 − 17.0 = 32.0 68.0 x 0.6 = 40.8
40.8 + 40.0 = 80.8
108.0 − 80.8 = 27.2
(68.0 + 27.2) −
108.0 = -12.8
Potatoes
157.5 − 40. = 117.5 117.5 / 4 = 29.4
52.0 − 29.4 = 22.6 117.5 x 0.6 = 70.5 70.5 + 40.0 = 110.5 157.5 − 110.5 = 47.0 (117.5 + 47.0) −
157.5 = 7.0
a
b
c
d
35
Table 16 Algorithms for variable-rate fertiliser application with dairy cows slurry (N:P = 6.4:1; Table 4) and additional mineral nitrogen and phosphorus fertiliser
in Germany. The fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class C (= P offtake by
crop; Table 11). Limitations by excess of soil nitrogen are not considered. All values are given in kg ha-1 a-1.
Crop
NSLa =
N offtake by crop
minus N from
additional delivery
PSlb =
multiple (N:P
ratio) of N rate
PMFc =
P offtake by crop
minus PSL
NSl-avld =
available N of NSl
Norge =
NSl-avl plus N from
subsequent
delivery
NMFf =
N offtake by crop
minus Norg (N
Wheat
198.9 − 40. = 158.9
158.9 / 6.4 = 24.8
31.5 − 24.8 = 6.7
158.9 x 0.5 = 79.5
79.5 + 40.0 = 119.5
198.9 − 119.5 = 79.5
N surplusg =
NSl plus NMF
minus Norg
offtake by crop
(158.9 + 79.5) −
198.9 = 39.5
Barley
115.5 − 40. = 75.5
75.5 / 6.4 = 11.8
24.5 − 11.8 = 12.7 75.5 x 0.5 = 37.8
37.8 + 40.0 = 77.8
115.5 − 77.8 = 37.8
(75.5 + 37.8) −
115.5 = -2.3
Rye
120.8 − 40. = 80.8
80.8 / 6.4 = 12.6
28.0 − 12.6 = 15.4 80.8 x 0.5 = 40.4
40.4 + 40.0 = 80.4
120.8 − 80.4 = 40.4
(80.8 + 40.4) −
120.8 = 0.4
Silage maize 180.5 − 40. = 140.5 140.5 / 6.4 = 22.0 33.3 − 22.0 = 11.3 140.5 x 0.5 = 70.3 70.3 + 40.0 = 110.3 180.5 − 110.3 = 70.3 (140.5 + 70.3) −
180.5 = 30.3
Rapeseed
134.0 − 40. = 94.0
94.0 / 6.4 = 14.7
31.2 − 14.7 = 16.5 94.0 x 0.5 = 47.0
47.0 + 40.0 = 87.0
134.0 − 87.0 = 47.0
(94.0 + 47.0) −
134.0 = 7.0
Sugar beet
108.0 − 40. = 68.0
68.0 / 6.4 = 10.6
24.0 − 10.6 = 13.4 68.0 x 0.5 = 34.0
34.0 + 40.0 = 74.0
108.0 − 74.0 = 34.0
(68.0 + 34.0) −
108.0 = -6.0
Potatoes
157.5 − 40. = 117.5 117.5 / 6.4 = 18.4 27.0 − 18.4 = 8.6
117.5 x 0.5 = 58.8 58.8 + 40.0 = 98.8
157.5 − 98.8 = 58.8
(117.5 + 58.8) −
157.5 = 18.8
a
b
c
d
36
Table 17 Algorithms for variable-rate fertiliser application with dairy cows slurry (N:P = 6.4:1; Table 4) and additional mineral nitrogen and phosphorus fertiliser
in Germany. The fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class A (= P offtake by
crop plus 25 kg P ha-1 a-1; Table 11). In this case, P fertilisation by slurry leads to N application above the legal limit of 170 kg N ha-1 a-1 or above the plants N
Crop
NSLa =
N offtake by crop
minus N from
additional delivery
PSlb =
multiple (N:P
ratio) of N rate
PMFc =
P offtake by crop
minus PSL
NSl-avld =
available N of NSl
Norge =
NSl-avl plus N from
subsequent
delivery
NMFf =
N offtake by crop
minus Norg (N
Wheat
198.9 − 40. = 158.9
158.9 / 6.4 = 24.8
56.5 − 24.8 = 31.7
158.9 x 0.5 = 79.5
79.5 + 40.0 = 119.5
198.9 − 119.5 = 79.5
N surplusg =
NSl plus NMF
minus Norg
offtake by crop
(158.9 + 79.5) −
198.9 = 39.5
Barley
115.5 − 40. = 75.5
75.5 / 6.4 = 11.8
49.5 − 11.8 = 37.7 75.5 x 0.5 = 37.8
37.8 + 40.0 = 77.8
115.5 − 77.8 = 37.8
(75.5 + 37.8) −
115.5 = -2.3
Rye
120.8 − 40. = 80.8
80.8 / 6.4 = 12.6
53.0 − 12.6 = 40.4 80.8 x 0.5 = 40.4
40.4 + 40.0 = 80.4
120.8 − 80.4 = 40.4
(80.8 + 40.4) −
120.8 = 0.4
Silage maize 180.5 − 40. = 140.5 140.5 / 6.4 = 22.0 58.3 − 22.0 = 36.3 140.5 x 0.5 = 70.3 70.3 + 40.0 = 110.3 180.5 − 110.3 = 70.3 (140.5 + 70.3) −
180.5 = 30.3
Rapeseed
134.0 − 40. = 94.0
94.0 / 6.4 = 14.7
56.2 − 14.7 = 41.5 94.0 x 0.5 = 47.0
47.0 + 40.0 = 87.0
134.0 − 87.0 = 47.0
(94.0 + 47.0) −
134.0 = 7.0
Sugar beet
108.0 − 40. = 68.0
68.0 / 6.4 = 10.6
49.0 − 10.6 = 38.4 68.0 x 0.5 = 34.0
34.0 + 40.0 = 74.0
108.0 − 74.0 = 34.0
(68.0 + 34.0) −
108.0 = -6.0
Potatoes
157.5 − 40. = 117.5 117.5 / 6.4 = 18.4 52.0 − 18.4 = 33.6 117.5 x 0.5 = 58.8 58.8 + 40.0 = 98.8
157.5 − 98.8 = 58.8
(117.5 + 58.8) −
157.5 = 18.8
a
b
c
d
37
Table 18 Algorithms for variable-rate fertiliser application with pig solid fraction (N:P = 1.8; Table 10) and additional mineral nitrogen fertiliser in Germany. The
fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class C (= P offtake by crop; Table 11).
Limitations by excess of soil nitrogen are not considered. All values are given in kg ha-1 a-1.
Crop
PSla =
P offtake
by crop
NSlb =
multiple (N:P
ratio) of P rate
NSl-avlc =
available N of NSl
Norgd =
NSl-avl plus N from
additional delivery
NMFe =
N offtake by crop
minus Norg
N surplusf =
NSl plus NMF minus
Wheat
31.5
31.5 x 1.8 = 56.7
56.7 x 0.6 = 34.0
34.0 + 40 = 74.0
198.9 − 74.0 = 124.9
(56.7 + 124.9) − 198.9 = -17.3
Barley
24.5
24.5 x 1.8 = 44.1
44.1 x 0.6 = 26.5
26.5 + 40 = 66.5
115.5 − 66.5 = 49.0
(44.1 + 49.0) − 115.5 = -22.4
Rye
28.0
28.0 x 1.8 = 50.4
50.4 x 0.6 = 30.2
30.2 + 40 = 70.2
120.8 − 70.2 = 50.6
(50.4 + 50.6) − 120.8 = -19.8
Silage maize 33.3
33.3 x 1.8 = 59.9
59.9 x 0.6 = 35.9
35.9 + 40 = 75.9
180.5 − 75.9 = 104.6
(59.9 + 104.6) − 180.5 = -16.1
Rapeseed
31.2
31.2 x 1.8 = 56.2
56.2 x 0.6 = 33.7
33.7 + 40 = 73.7
134.0 − 73.7 = 60.3
(56.2 + 60.3) − 134.0 = -17.5
Sugar beet
24.0
24.0 x 1.8 = 43.2
43.2 x 0.6 = 25.9
25.9 + 40 = 65.9
108.0 − 65.9 = 42.1
(43.2 + 42.1) − 108.0 = -22.7
Potatoes
27.0
27.0 x 1.8 = 48.6
48.6 x 0.6 = 29.2
29.2 + 40 = 69.2
157.5 − 69.2 = 88.3
(48.6 + 88.3) − 157.5 = -20.6
a
b
c
PSl = phosphorus applied with slurry; NSL = nitrogen applied with slurry; NSl-avl = plant available nitrogen in slurry. As the solid fraction is still liquid manure,
the same percentage of available N as for pig slurry was used; d Norg = nitrogen from organic sources: plant available nitrogen in slurry plus additional delivery
from soil and preceding crop residues. 40 kg N ha-1 a-1 is the maximum value which can be taken into account (Sächsische Landesanstalt für Landwirtschaft,
2007); e NMF = nitrogen applied with additional mineral fertiliser; f mismatch of plant offtake of available N for optimum yield and total N delivery (slurry,
mineral fertiliser, additional delivery).
38
Table 19 Algorithms for variable-rate fertiliser application with pig solid fraction (N:P = 1.8; Table 10) and additional mineral nitrogen fertiliser in Germany. The
fertilisation follows the P demand of the crop (Table 12) and the P fertiliser recommendation for soil test phosphorus class A (= P offtake by crop plus 25 kg P ha1 -1
a ; Table 11). In this case, P fertilisation by slurry leads to N application above the legal limit of 170 kg N ha-1 a-1 or above the plants N demands; hence, the
slurry application follows the plants N demand and missing P is applied by mineral fertiliser. Limitations by excess of soil nitrogen are not considered. All values
are given in kg ha-1 a-1.
Crop
PSla =
P offtake
by crop
NSlb =
multiple (N:P
ratio) of P rate
NSl-avlc =
available N of NSl
Norgd =
NSl-avl plus N from
additional delivery
NMFe =
N offtake by crop
minus Norg
N surplusf =
NSl plus NMF minus
Wheat
56.5
56.5 x 1.8 = 101.7
101.7 x 0.6 = 61.0
61.0 + 40 = 101.0
198.9 − 101.0 = 97.9
(101.7 + 97.9) − 198.9 = 0.7
Barley
49.5
49.5 x 1.8 = 89.1
89.1 x 0.6 = 53.5
53.5 + 40 = 93.5
115.5 − 93.5 = 22.0
(89.1 + 22.0) − 115.5 = -4.4
Rye
53.0
53.0 x 1.8 = 95.4
95.4 x 0.6 = 57.2
57.2 + 40 = 97.2
120.8 − 97.2 = 23.6
(95.4 + 23.6) − 120.8 = -1.8
Silage maize 58.3
58.3 x 1.8 = 104.9
104.9 x 0.6 = 62.9
62.9 + 40 = 102.9
180.5 − 102.9 = 77.6
(104.9 + 77.6) − 180.5 = 1.9
Rapeseed
56.2
56.2 x 1.8 = 101.2
101.2 x 0.6 = 60.7
60.7 + 40 = 100.7
134.0 − 100.7 = 33.3
(101.2 + 33.3) − 134.0 = 0.5
Sugar beet
49.0
49.0 x 1.8 = 88.2
88.2 x 0.6 = 52.9
52.9 + 40 = 92.9
108.0 − 92.9 = 15.1
(88.2 + 15.1) − 108.0 = -4.7
Potatoes
52.0
52.0 x 1.8 = 93.6
93.6 x 0.6 = 56.2
56.2 + 40 = 96.2
157.5 − 96.2 = 61.3
(93.6 + 61.3) − 157.5 = -2.6
a
b
c
PSl = phosphorus applied with slurry; NSL = nitrogen applied with slurry; NSl-avl = plant available nitrogen in slurry. As the solid fraction is still liquid manure,
the same percentage of available N as for pig slurry was used; d Norg = nitrogen from organic sources: plant available nitrogen in slurry plus additional delivery
from soil and preceding crop residues. 40 kg N ha-1 a-1 is the maximum value which can be taken into account (Sächsische Landesanstalt für Landwirtschaft,
2007); e NMF = nitrogen applied with additional mineral fertiliser; f mismatch of plant offtake of available N for optimum yield and total N delivery (slurry,
mineral fertiliser, additional delivery).
39
6.3
Crop rotation
The advantage of considering crop rotation in combination with manure is that the mismatch of
plant offtake of available N for optimum yield and the total N delivery can be lowered. In the
following, three examples for crop rotations on soils with deficient and optimum P supply status
will be presented, which are based on the fertiliser rates presented above. Combinations of slurry,
slurry solid fraction and mineral fertiliser are used.
The first example (Table 20 and Table 21) deals with a pig farm and a rotation of wheat, maize and
sugar beet. On STP class A and class C soils, the fertilisation cause an excess of stable N on both
wheat and maize. This N excess is theoretically equalised in the third year by N depletion. Sugar
beet at the end of the rotation can satisfy a great proportion of its nitrogen demand from the
mineralisation of manure applied in previous years (Sächsische Landesanstalt für Landwirtschaft,
2007). This is caused by a long growing season in the warm months.
The second example (Table 20 and Table 21) presents a pseudo crop rotation with wheat in two
subsequent years after one year with rapeseed. The third example (Table 20 and Table 21) deals
with dairy slurry and a crop sequence of wheat, rye and sugar beet. As for pig slurry, it is easier to
construct a balanced N application within a crop rotation with products with different N:P ratios.
Dairy cow slurry solid fractions have a N:P ratio of 3.6, which differs from the N:P ratio of 6.4 of
dairy cows slurry. The N:P ratio of the solid fraction is close to pig slurry (Table 10); therefore, the
calculations are similar to Table 13-Table 15 and not presented in this report.
All examples show that the soils with a P deficiency (Table 21) receive, with one exception, only
slurry solid fractions. This is the result of the higher P content (lower N:P ratio) of the solid
fractions. In turn, the production of ammonia water from the liquid fraction allows for an
application of a slurry product on soils with excess P. Consequently, fractionation of slurry is
helpful for a variable-rate application.
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Table 20 Examples for fertilisations with pig and dairy cow slurry on soil with optimum P status (soil test
phosphorus class C) within three-year crop rotations. Detailed calculations for the values are stated in Table
13, Table 16, and Table 18, details for dairy cow solid fraction are not given, but calculations were similar to
Table 13. All values are given in kg ha-1 a-1.
Manure
P needa
PSlb
PMFc
N needa
NSlb
NMFc
N surplusd
Pig slurry
1
Wheat
Slurry
31.5
31.5
00.0
198.9
126.0
083.3
10.4
2
Silage maize
Slurry
33.3
33.3
00.0
180.5
133.0
060.7
13.2
3
Sugar beet
Solid
fraction
24.0
24.0
00.0
108.0
043.2
042.1
-22.7
88.75
00.0
302.2
186.0
00.9
Year
Crop
Total
Pig slurry
1
Rapeseed
2
Wheat
3
Wheat
Slurry
31.2
31.2
00.0
134.0
124.8
19.1
09.9
Solid
fraction
Slurry
31.5
31.5
00.0
198.9
056.7
124.9
-17.3
31,.5
31.5
00.0
198.9
126.0
083.3
10.4
94.2
00.0
307.5
227.0
03.0
Total
Dairy cow slurry
1
Wheat
2
Rye
3
Sugar beet
Total
Solid
fraction
Slurry
31.5
31.5
00.0
198.9
113.4
090.9
05.4
28.0
12.6
15.4
120.8
080.8
040.4
00.4
Solid
fraction
24.0
24.0
00.0
108.0
086.4
016.2
-5.4
31.5
00.0
280.6
148.0
00.4
a
Fertiliser recommendations for the crops need; b applied with slurry; c applied with additional mineral
fertiliser; d mismatch of plant offtake of available N for optimum yield and total N delivery (slurry, mineral
fertiliser, additional delivery). Negative values indicate a depletion of stable N forms by mineralisation.
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Table 21 Examples for fertilisations with pig and dairy cow slurry on soil with optimum P status (soil test
phosphorus class A) within three-year crop rotations. Detailed calculations for the values are stated in Table
13, Table 16, and Table 18, details for dairy cow solid fraction are not given, but calculations were similar to
Table 13. All values are given in kg ha-1 a-1.
Year
Crop
Pig slurry
1
Wheat
2
Silage maize
3
Sugar beet
Manure
P needa
PSlb
PMFc
N
needa
NSlb
NMFc
N surplusd
Solid
fraction
Solid
fraction
Solid
fraction
56.5
056.5
00.0
198.9
101.7
097.9
00.7
58.3
058.3
00.0
180.5
104.9
077.6
01.9
49.0
049.0
00.0
108.0
088.2
015.1
-4.7
164.0
00.0
294.75
190.6
-2.1
Total
Pig slurry
1
Rapeseed
2
Wheat
3
Wheat
Slurry
56.2
023.5
32.7
134.0
094.0
037.6
-2.4
Solid
fraction
Solid
fraction
56.5
056.5
00.0
198.9
101.7
097.9
00.7
56.5
056.5
00.0
198.9
101.7
097.9
00.7
137.0
32.7
297.4
233.4
-1.0
56.5
044.1
12.4
198.9
158.9
063.6
23.6
53.0
022.4
30.6
120.8
080.8
032.3
-7.7
49.0
018.9
30.1
108.0
068.0
027.2
-12.8
085.5
73.0
307.7
123.1
03.1
Total
Dairy cow slurry
1
Wheat
2
Rye
3
Sugar beet
Total
Solid
fraction
Solid
fraction
Solid
fraction
a
Fertiliser recommendations for the crops need; b applied with slurry; c applied with additional mineral
fertiliser; d mismatch of plant offtake of available N for optimum yield and total N delivery (slurry, mineral
fertiliser, additional delivery). Negative values indicate a depletion of stable N forms by mineralisation.
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7
Conclusions
We presented prerequisites and the framework for a variable-rate application of slurry and some
algorithms for such fertilisations. With regard to globally limited P reserves it is recommended to
limit maximum rates of manure on P basis, rather than the N demand. Variable rate application of
slurry is required on fields with zones of an insufficient P supply that need P rates that are higher
than the offtake by harvest products. On soils where the P supply is sufficiently high, P rates by
slurry can be applied uniformly at rates that equal the offtake. N will be applied in organic and
mineral form so that for both nutrients, N and P, the demand will correspond with the actual
fertiliser rate. For the calculation of variable N rates soil data, geomorphology, crop demand are
required. Different types of slurry or slurry-based products have been used for the calculations. An
excess of plant-available and mobile N is avoided so that nutrient losses to the environment are
minimised. Thus a balanced application of nitrogen and phosphorus is achieved.
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8
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phosphorus contents in pig slurries. Biosystems Engineering 85(1), 121–128.
Zimmermann, A., Thiessen, E. & Hartung, E. (2008). Near-infrared spectroscopy (NIRS) for a
nutrient based slurry application. In: Agricultural and biosystems engineering for a
sustainable world. International Conference on Agricultural Engineering, 24.06.2008,
Hersonissos, p. OP-300.
Zunhammer, S.-M. (2011). Entwicklung der Ausbringtechnik für flüssige organische Dünger.
URL:
http://www.tec.wzw.tum.de/fileadmin/user_upload/Vortrag_Zunhammer.pdf
(accessed 22.05.2013).
The
project
is
partly
financed
by
the
European
Union
-
49
This report in brief
About the project
An undesired surplus of nutrients in agricultural soils can
be attributed among others to a uniform application of
fertilisers as it does not address the small-scale variation
of nutrients in soils. Site-specific fertilisation can reduce
nutrient surpluses. Algorithms for a site-specific input of
manure are missing so far, but are crucial for a purely
demand-driven input of nutrients. This report describes
conditions and algorithms for the variable-rate application of slurry.
The Baltic Sea Region is an area of intensive agricultural
production. Animal manure is often considered to be a
waste product and an environmental problem.
Slurry application should follow the P demand of crops as
otherwise an overfertilisation with P is common. Consequently, soils with excessively high P contents receive no
P fertiliser, soils with sufficiently high P content application rates equal the P offtake by harvest products and
on soils with an insufficiently high P-content for maximum yields application rates need to be higher than the
offtake. Nitrogen will be applied in organic and mineral
form so that for both nutrients, N and P, the demand will
correspond with the actual fertiliser rate. Thus a balanced
application of nitrogen and phosphorus is achieved.
The long-term strategic objective of the project Baltic
Manure is to change the general perception of manure
from a waste product to a resource. This is done through
research and by identifying inherent business opportunities with the proper manure handling technologies and
policy framework.
To achieve this objective, three interconnected manure
forums has been established with the focus areas of
Knowledge, Policy and Business.
Read more at www.balticmanure.eu.
This report on the “Algorithms for variable-rate application of manure” was prepared as part of work package 4
on manure standards of the project Baltic Manure.
www.balticmanure.eu
Part-financed by the European Union
(European Regional Development Fund)

Algorithms for variable-rate application of manure

Transcription

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