Managing Soil Fertility: Targets to maximise productionD.P_Managing-Soil-Fertility_Mallow_Jan2017..pdf · Managing Soil Fertility: Targets to maximise production Dr David P. Wall

Managing Soil Fertility:

Targets to maximise production

Dr David P. Wall Teagasc, Johnstown Castle, Co Wexford

David Wall_Soil Fertility Management_IDIA 2017 2

Outline

Soil fertility trends on dairy farms

5 Steps to soil fertility management

• Soil Testing

• Soil pH and Lime

• Determine P & K requirements

• Best use of Organic manures

• Apply a balanced fertilizer programed

Soil Fertility and Productivity Targets


National Soil Fertility trends

Soils Data Base maintained at Teagasc

Johnstown Castle

2015

~ 36,000 samples submitted through Teagasc for soil analysis

Samples submitted for analysis from each county in Ireland

Dairy: National soil pH trend

n = 113,606 soil samples (average 12,622 samples/annum) Wall et al. 2015

Pro

po

rtio

n o

f so

il sa

mp

les

in e

ach

Ind

ex

27% 22% 19% 25% 23% 20%

14% 19% 20%

28% 28% 29%

29% 26% 26%

26% 25% 24%

19% 20% 20%

21% 19% 21%

22% 20% 19%

13% 15% 15%

13% 15% 17%

19% 17% 17%

14% 16% 17% 12% 17% 16% 18% 18% 19%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

20

07

20

08

20

09

20

10

20

11

20

12

20

13

20

14

20

15

>6.5 6.2-6.5 5.9-6.2 5.5-5.9 <5.5


0

500

1000

1500

20001

97

01

97

11

97

21

97

31

97

41

97

51

97

61

97

71

97

81

97

91

98

01

98

11

98

21

98

31

98

41

98

51

98

61

98

71

98

81

98

91

99

01

99

11

99

21

99

31

99

41

99

51

99

61

99

71

99

81

99

92

00

02

00

12

00

22

00

32

00

42

00

52

00

62

00

72

00

82

00

92

01

02

01

12

01

22

01

32

01

4To

nn

ag

e o

f L

ime (

'000 t

/yr)

Year

Lime usage 1970 -2014


Phosphorus fertility

declining high status soils

Low proportion of soils at target index

Large proportion with sub-optimum P

Potassium fertility

Majority soils with sub-optium K

Steady decline in soil K fertility

over last decade

Soil P & K fertility status and trends


N, P and K use between 1990 and 2011 relative to 1990 (N= 379,000 kg ,P= 65,000 kg , K=158,000 kg)

N

K

P

High fertilizer N allowance and most restrictive P allowance in Europe

P = 20,000 kg

K = 52,000 kg


All farms ~153,500 soil samples

9 10 11 11 19 22

29 25 25 28

32%

26 24 23 24

27 28

29

27 27 29

28% 28 31 30 29

27

27

23

25 25

23 23%

36 35 37 36 28

22 19

23 23 19 17%

0

10

20

30

40

50

60

70

80

90

100

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Perc

en

tag

e o

f sam

ple

s i

n e

ach

P i

nd

ex

Index 4(High)

Index 3(Optimum)

Index 2(Low)

Index 1(V.Low)

Reducing soil P loss

risk

Soil P Fertility trends – Dairy

Lower N fertiliser

and slurry nutrient

efficiency


Soils with Optimum Soil Fertility

Optimum 10%

90%

Good Overall Fertility : Soil pH > 6.2; Soil P and K Index ≥ 3


What quantities of nutrients are

required? Nutrient off-take from the grazing platform

Milk (18,000 litres/ha)

+ 3Cows & Calves LW/ha

110 kg N

20 kg P

31 kg K

5 kg S

Nutrients required

For 12 t DM/ha

50 kg

EC Fertiliser

?

Losses (N, S, K , P)

Lock-up(P, N, S,

K)


What quantities of nutrients are

required?

Losses (N, S, K , P)

Lock-up(P, N, S,

K)

50 kg

EC Fertiliser

N – 250 kg/ha

P – 25 kg/ha

K – 45 kg/ha

S – 20 kg/ha

Highly Stocked Grazing

Block

Typical Maintenance


Steps to Soil Fertility Management

Index Description

1 Very Low

2 Low

3 Target

4 High


Soil Testing – Cost / Benefit

~ 10% of soils are optimised for P, K & lime

• If no soil test and assume Index 3, then you are likely to be wrong in 90% of fields !!

Cost

• Consider relative to fertilizer cost?

» 1 sample = 4 ha for 5 years @ €25

» €1.25 /ha/yr (50c per acre)

» 1 kg of P = €2 !!!

= € 300-500 / tonne ???

N P K Fertilizer


Soil testing – Why & How ?

How ?

• Sample Area

• Minimum 20 cores per sample

• Full 10 cm depth

When ?

• Late Autumn / Early Spring ideal

» Results ready for fertiliser planning for the coming year




Soil pH and Liming

Optimum pH for grassland = 6.2 - 6.3 » Maximum nutrient release from soils

» Soil biological activity

67 % of grassland soil < 6.2

Response to fertiliser N, P and K on acid soils ????

6.5 4.5 7.0 5.0 7.5 5.5 6.0

P

N

K

• Soil P reserve less

available

• Fertilisers less

available


Effect of soil pH on P Availability

` 3 4 5 6 7 8 9 Soil pH

Acidic Soils Alkaline Soils

Ph

osp

ho

rus F

ixati

on

High

Med

Low

Fixation by

Iron &

Aluminium

Fixation

by

Calcium

Plant

Available

P

D.P. Wall, 2015


Effect of P and Lime of soil P availability

Sheil, Wall & Lalor,

2015, FAI

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015


Average response across 2 sites

Effect of P and Lime of grass yield

Average soil pH: 5.2 6.4 5.2 6.4

D.P. Wall et al., 2015

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015


Lime in grassland

1 ha

Up to 250-625 kg/ha/yr of lime in

drainage

100 kg

=

180-220

kg lime

N

fertiliser

Offtake 1 bullock

25 kg of Lime

1000 litres milk

3 kg of Lime

5 t/ha silage DM

75 kg of Lime

Grassland Example

150 kg/ha N – 300 kg

10,000 litres milk – 30 kg

Lime loss in drainage – 250-625 kg

Total lime required –

580 – 955 kg/ha/yr

1-2 ton/acre every 5 years


Lime requirements

Advice is to apply lime in a 3-5 year cycle

• Grassland typically requires between 0.5 - 1 t/ha/yr

• Target soil pH: Mineral soils 6.3, Peat soil 5.5

Exceptions

• High Mo soils and grassland don’t exceed pH 6.2

» Lime requirements reduced by 5 t/ha

• Where advice is > 7.5 t/ha

» Split application

» 7.5 t/ha now

» Remainder after 2 years

» Precaution to reduce risk of trace element problems



Index Description

1 Very Low

2 Low

3 Target

4 High


Interpreting soil test results - P & K

Convert test result into soil Index (P & K grassland index below)

Target = All soils in Index 3 for P and K !

• Only ~ 25% at present

Soil Index Description Soil test P

(mg L-1)

Soil test K

(mg L-1)

1 Very low 0 – 3.0 0 – 50

2 Low 3.1 – 5.0 51 – 100

3 Medium 5.1 – 8.0 101 – 150

4 High ≥ 8.1 ≥ 151

Soil Index Description Soil test P

(mg L-1)

Soil test K

(mg L-1)

1 Very low 0 – 3.0 0 – 50

2 Low 3.1 – 5.0 51 – 100

3 Medium 5.1 – 8.0 101 – 150

4 High ≥ 8.1 ≥ 151


Maintenance P and K advice Grazed Swards Silage Swards

Stocking Rate (kg/ha Org N) Soil P

Index < 130 131-170 171-210 >210 Cut Once

Cut

Twice

1 30 34 39 43 +20 +30

2 20 24 29 33 +20 +30

3 10 14 19 23 +20 +30

4 0 0 0 0 0 0

Grazed Swards Silage Swards

Stocking Rate (kg/ha Org N) Soil K

Index < 130 131-170 171-210 >210 Cut Once

Cut

Twice

1 85 90 95 100 +120 +155

2 55 60 65 70 +120 +155

3 25 30 35 40 +120 +155

4 0 0 0 0 0 0


Soil P and K build up - Grassland

P K

Index 2

10 kg/ha

(8 units/acre)

30 kg/ha

(24 units/acre)

Index 1

20 kg/ha

(16 units/acre)

60 kg/ha

(48 units/acre)

16% P

25 kg

16% P

50 kg

Muriate

50% K

25 kg

Muriate

50% K

50 kg

Apply build up +

maintenance in

Index 1 and 2

Apply for 5 years

or until soil test

shows increase



27 Lalor et al. 2013. IFS Conference, Cambridge. 6-7 Dec, 2012.

Contribution to Slurry Value

Cattle Slurry

N

12%

P

19%

K

69%

Majority of the value is in P

and K

• Aim to get best use of both P

and K in slurry

• Timing or method

» No effect on P and K

» Big effect on N


Slurry Value 1000 gallons = ??

50 kg

N P K

4 - 0.7 - 5

50 kg

N P K

6 - 5 - 38

50 kg

N P K

3 - 5 - 38

Soiled Water

All Year

Cattle Slurry (Splash plate)

Spring Summer

50 kg

N P K

19 - 7 - 20

Pig Slurry

Trailing Shoe

+ 3 units N

/ 1000 gallons

In spring or

summer

50 kg

N P K

3 - 2.5 - 12

FYM (1 ton)

5 / 1000 gals 24 / 1000 gals 26 / 1000 gals

28 / 1000 gals 10 / ton

Beware of

Average Values

Highly Variable


Decisions with slurry

1. Where to spread

» P & K requirements

» Target fields with:

low soil P and K

High requirements (e.g. silage)

2. When to spread

» Maximise N availability

» Weather as important as

season, but spring generally

best

» Trailing shoe / band spreader

will also increase N value




Nutrient Balance – What is the Weakest

Link ?

Nutrient in shortest supply limits determines yield

• Especially true with P and K

Fertilizer Planning

• Soil tests & Cropping

• Slurry & fertilizers

» Straight K

» N-P products

» N-K products

» Sulphur and micro nutrients

N P K Fertilizer

N P Fertilizer

K Fertilizer


Cost of lost production at Index 1 & 2

Example

• Dairy – 2 cows / ha

• Maintenance advice (grazing: Index 3 ) = 13 kg/ha P & 35 kg/ha K

• Cost of maintenance P & K = €60 /ha/yr

Production loss in Index 1 vs. Index 3

• Approximately 2.0 t/ha/yr of grass DM (range 1-5 t/ha)

• Worth ~ €360 /ha/yr

Additional P and K for build up = 20 kg/ha P & 60 kg/ha K

• Additional Cost = €90 /ha/yr until soil P / K increases

• Long-term investment – benefits of increasing to Index 3

• Return on Investment 4:1 (€ grass production : € soil fertility)

Soil pH needs to be

right as well !


Urea or Stabilised Urea

Why look at it now?

Cost & yield Urea-N costs less

than CAN-N: 26%

less (CSO, 2014)

Is there a yield

penalty?

Internationally urea

is more available

than CAN

GHG • Ag. approx. 1/3

national emissions

• Committed to reduce by 20% by 2020

• N addition causes N2O loss

• Smart solutions?

Ammonia (NH3)

• Ag. accounts for c. 98.5% of national emissions

• Committed to reduce by 30% by 2030

• Urea looses NH3!

Nitrogen fertiliser selection


Nitrogen fertiliser selection


Soil Fertility Management Targets Have soil analysis for whole farm

Soil pH between 6 and 6.5 in all fields

• Note: target pH 5.5 for peat soils

P and K Index 3 in all fields

• Index 4 is a resource Exploit it

• Index 1 & 2 should be increased to Index 3

Optimise slurry first – then top up with fertilizer as required

Nutrient inputs in proper balance

• Fertilizer planning is key

• Increase farm sustainability with N fertiliser source selection

Documents

Managing Soil Fertility: Targets to maximise productionD.P_Managing-Soil-Fertility_Mallow_Jan2017..pdf · Managing Soil Fertility: Targets to maximise production Dr David P. Wall