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Lecture 4 Flashcards

1
Q

Whats the purpose of fertiliser application to grassland ?

A

to produce an appropriate level of soil fertility
to support adequate crop growth (and animal
performance) and to maintain an adequate level of soil fertility by replacing all nutrient off-takes, be they in the forms of milk, meat or crops
(grass/silage)

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2
Q

Whats the N content g/kg DM?
What does N do?

A

20-50
Drives plant growth , element of AA

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3
Q

Whats the P content g/kg DM?
What does P do?

A

2-4
Root development , energy utilisation, cell division

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4
Q

Whats the K content g/kg DM?
What does K do?

A

25-40
Maximise N use , sugar formation

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5
Q

Whats the 3 main elements that need to be returned to the soil following grazing/silage harvesting

A

Nitrogen
Phosphorus
Potassium

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6
Q

What is the most abundant element in the atmosphere and what % is it?

A

Gaseous N
78%

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7
Q

Grass requires 2 things for growth:

A

-Nitrate
-Ammonia ions

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8
Q

Under 2 cut system how many kg of N is removed?

A

200-500kg

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9
Q

15t DM/ha/year requires the uptake of how much N/Ha?

A

450kg/N/ha

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10
Q

Whats the average cp% for 15,000kg DM

A

18.75% CP

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11
Q

Whats the minimum N/kg/DM required for optimum photosynthesis?

A

30g N/kg/DM

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12
Q

N2

A

di-nitrogen gas

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13
Q

NO2

A

Nitrite***

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14
Q

NO3

A

Nitrate (Nitrate leaching; soil collides negatively charges)

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15
Q

N2O

A

Nitrous oxide
(potent GHG)

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16
Q

NH3

A

Ammonia
(Ammonia Volatilization)

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17
Q

NH4+

A

Ammonium***

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18
Q

How is nitrate poisoning caused?

A

High nitrate levels and it usually occurs in late autumn or winter , particularly during a flush of growth after a dry period.
Nitrate levels build up in herbage when nitrate is taken up by the plant faster than it can be converted into protein

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19
Q

How does nitrate enter the plant?

A

Passively- directly stored in the leaf tissue.

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20
Q

When plant roots uptake Nitrate what is released by the plant root?

A

OH-

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21
Q

What can be converted directly into the root?

A

Ammonia

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22
Q

When plant roots uptake Ammonium what is released by the plant root?

A

H+

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23
Q

Definition: Fixation

A
  • fixation is the process of converting dinitrogen gas (N2) to chemically reactive forms
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24
Q

Definition: Mineralisation

A
  • Microorganisms decomposed OM into easily available N forms to plants
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25
Q

Definition: Nitrification

A
  • microbial process by which ammonia is converted to nitrite and nitrate
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26
Q

Definition: Leaching

A
  • The nitrate is soluble and is leached easily when excess water percolates through the soil
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27
Q

Definition : Plant assimilation

A

Plant roots take up nitrogen in primarily the nitrate or ammonium forms

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28
Q

Definition : Denitrification

A

Denitrification is the process which microbes convert nitrate to nitrogen gas

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29
Q

Definition: Volatilisation

A
  • Ammonium in the soil is converted to ammonia, which is lost as a gas
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30
Q

Definition: Immobilisation

A
  • nitrate and ammonium are taken up by soil organisms and
    therefore become unavailable to crops
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31
Q

LOOK OVER THE N CYCLE

A
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32
Q

Response to nitrogen:
15-25 kg DM/kg N=

A

Up to 250-350 kg/ha

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33
Q

Response to nitrogen:
5-15 kg DM/ Kg N=

A

350-450 kg/ha

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34
Q

When does N uptake increase?
When does it peak?

A

March and April
Peaks at 3.5 kg N/ha/day during late May

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35
Q

What % of fertiliser N is taken up by grass?

A

70-80%

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36
Q

The average grass growth response is *** at an application rate of between **

A

-17 kg DM/ha per kg N
-150-200kg N/ha

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37
Q

What was the nitrogen response as N rate increased?

A

Reduced

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38
Q

N intake :(4)

A

-In the plant Nitrate is converted to ammonium ions
-NH3 combines with CHO to synthesize AA
-AA= Proteins
-N take up that is surplus to requirements remains in the plant tissue as non-protein N (NPN)

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39
Q

What does N deficiency look like in grass?

A

Light green colour with yellowing leaf base , reduced growth and sparse ground cover due to lack of N
-Stunted grass growth
-Leaved ranging in colour from pale green to yellow
-Evident in old leaves first beginning at the tips
-Root growth becomes stunted and are less well able to seek out nutrients

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40
Q

List sources of N: (6)
Where must this be accounted?

A
  • Atmospheric deposition (12 kg/ha/year)
  • Background release (soil organic N)
  • Clover (100-150 kg/ha/year)
  • Animal excreta
  • FYM/slurry
  • Fertiliser
  • Must account for all sources in a nutrient
    management plan (NMP)
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41
Q

What % of OM does soils contain?
How much organic N?

A

5-20%
These contain large stores of organic N (5000+ kg/ha)

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42
Q

What % is available to the grass plant in any year?

A

-2%
-98% unavailable

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43
Q

Average background N release how much kg N/ha?

A

124kg
(40-330kg)

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44
Q

What renders available N?
What is increased following ploughing?

A
  • Constant turnover renders some N available
  • Mineralization is increased following ploughing
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45
Q

Where is the highest available kg/N/ha/yr?

A

220 kg N/Ha/Yr

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46
Q

Where is the lowest available kg/N/ha/yr?

A

Drumlins

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47
Q

Where is the average available kg/N/ha/yr?

A

140

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48
Q

Lower quantities of N are found in what type of soils?

A

shallow topsoil with lighter arable soils

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49
Q

Higher quantities of N are found in what type of soils?

A

deeper topsoil with heavier soils e.g. long-term grassland

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50
Q

What is also important when it comes to availability of N from grassland soils in Ireland?

A

-Soil OM
-Drainage

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51
Q

When does the highest N release from soil occur?

A

Late spring and early autumn when soil temperature and moisture levels are favourable

52
Q

During winter months :
Higher than general estimates of 200 to 250 g/ha/day which would be sufficient to produce :

A

6.5 to 7.5 kg/DM/ha/day

53
Q

What % of N consumed in herbage is excreted
depending on the type and class of animal and
diet offered

A

75-90%

54
Q

What animals utilize the least and the most :

A

-Beef Store cattle-Least
-Dairy cows- most

55
Q

Whats important to note about dairy cows and N?

A

While dairy cows utilize the most of N consumed, they are still very inefficient users of N.

56
Q

How much N is in dung? and how much is in urine?
Are they both available?

A

Approx. ¼ of N is in the dung (not immediately
available) and ¾ in the urine (available)

57
Q

PRG contains high levels of ?

A

RDP
Rumen Degradable Protein - 81%

58
Q

What animal has the highest N excretion rate (apart from dairy cows)

A

50kg

59
Q

Whats the aim of the EU nitrates Directive?

A

to prevent pollution of surface waters and groundwater from agricultural sources and to protect and improve water quality.

60
Q

Dairy farm N banding:
-Dairy cow 2022:
-Dairy cow 1st band:
-Dairy cow 2nd band:
-Dairy cow 3rd band:
What is N excretion rate determined by?

A

-89
-80
-92
-106
-Milk yield /annum (for 3 preceding years )

61
Q

Average DM% cattle slurry on irish farms is ?

A

6.3%
(0.4-11.9%)

62
Q

Watery slurry or parlour washings has what sort of DM content?

A

Low DM content

63
Q

Increase DM=

A

Increased nutrient value

64
Q

What does N fertiliser do for your grass?
-What does it supply?
-Ammonium that’s not take up by the roots is converted to what?

A
  • Increase DM yield
  • Reduce seasonality of growth
  • Extend the grazing season
  • Supply both nitrate and ammonium**
  • Urea following application is converted to ammonium (46% N)
  • Ammonium not taken up by the roots is converted to nitrate – losses via ammonia gas also
65
Q
  • CAN (calcium ammonium nitrate) supplies nitrate & ammonium What % N?
A

27% N

66
Q
  • Urea following application is converted to ammonium what % N?
A

46%N

67
Q

How much N per acre?

A
  • Units/acre x 1.25 = kg/ha
  • 50 kg or 500 kg bags typically
68
Q

Example: 2.5 ha field requiring 30 kg N/ha

A
  • To apply 30 kg N/ha of Protected urea – 46% N
  • 30 / 0.46 = 65 kg of Protected urea product/ha
  • Therefore, 65 kg x 2.5 ha = 163 kg/ha of
    Protected urea product
69
Q

Urea vs CAN:

A

Urea= straight urea
CAN= goes into soil as ammonium or nitrate

70
Q

What pastures should you fertilise first?

A

– Give priority to pastures with the greatest production potential

– Ryegrass-dominant pastures
– Pasture height of 5-8 cm (cattle), 3-6 cm (sheep)
– High fertility (P-K-S), well-drained soils

71
Q

What degrees is the minimum for grass growth?

A

5 degrees

72
Q

What cm is low?

A

5cm or less

73
Q

What cm is medium, high?

A

10cm and over

74
Q
  • Which pastures to fertilise with urea?
A

– Those with the greatest production potential
* Ryegrass dominant
* Pasture height of 5-8 cm (cattle), 3-6 cm (sheep)
* High fertility (P-K-S), well drained soils

75
Q

How much urea?

A

– 28.8 kg N/ha (about 0.5 bags/ac) at GRANGE
– BUT, response depends on soil, pasture, management

76
Q

When to apply urea?

A

– While 5-cm soil temperature is above 5°C and increasing
i.e. when most pastures are starting to grow

77
Q

Whats the spring N recommendation?

A

60 kg N/ha split 33:66 between
February and March
Nitrogen response reduced as N rate increased

78
Q

EU Nitrates Directive - National Action Programme
(NAP) regulations, statutory instrument (SI) 31 of 2014
– the European Communities (Good Agricultural
Practice for Protection of Waters) Regulations 2014

Whats the livestock manure loading shall nor exceed?

Can apply for derogation to farm up to?

A

❖ Livestock manure loading shall not exceed 170 kg organic N/ha/year

❖ Can apply for derogation to farm up to 220kg organic N/Ha /year

79
Q

Effect of season on herbage DM response to
fertiliser N- when do you get the best response ?

A

May - 15-25
June- 30-40
July- 20-30
Kg DM/kg N

80
Q

If N is not being taken up by the plant, where does it go?

A
  • Leaching – The nitrate is soluble and is leached easily when excess water
    percolates through the soil
  • Denitrification– Denitrification is the process that microbes converts nitrate to
    nitrogen gas
  • Volatilisation– the loss of nitrogen to the atmosphere as ammonia gas (NH3)
    from soils or from fertiliser applied to soil surfaces (N2O)
81
Q

Nitrate Leaching:
What is a disadvantage ?

A
  • Washing of nitrates from the soil
  • Nitrate mobility is a disadvantage with high
    rainfall, where the level of rain exceeds the
    ability of evapotranspiration to remove water
    from the soil
  • Water and nitrates pass down through the soil – Away from plant roots and lost to water courses
82
Q

Cows grazing both plantain and plantain - clover mix excreted a urinary N concentration of ** then cows grazing the ryegrass/white clover in March and April , respectively.

A

50-53%

83
Q

The quantity of NO3-N leached in drainage was ** lower from plantain and plantain -clover mix plots from the ryegrass/white clover pasture, however overall losses were low from all treatments. These results demonstrate the potential benefit of plantain pastures as a natural mitigation option to reduce the urinary N execretion from dairy cows and the NO3-N leached from dairy farms systems:

A

90-85%

84
Q

Denitrification SMD
Where does it occur?
What detach?
What releases?

A
  • Heavy waterlogged soils (SMD -10)
  • Soil becomes depleted of oxygen
  • Bacteria detach O2 from nitrate (NO3)
  • Release N2O and N2 gases
85
Q

Zones A,B,C (Donegal and Leitrim),D(Cavan and Monaghan)
Whats the Storage period?

A

A- 16 weeks
B-18 weeks
C- 20 weeks
D- 22 weeks

86
Q

To reduce the impact of nutrient losses in the riskiest period, the spreading of soiled water will be prohibited for all milk producers from the following dates:

A

– Between 21st and 31st December 2022
– Between 10th and 31st December 2023
– Between 1st and 31st December 2024 with exception of winter/liquid milk producers
– Between 1st and 31st December 2025 onwards for winter/liquid milk producers

87
Q

All holdings producing soiled water must have minimum 31 days storage from

A

1st December 2024 with exception
of winter milk producers where storage must be in place by 1st December 2025

88
Q

What % of Ammonia emissions come from agriculture?
Whats ammonia associated with ?

A

-99%
-Application of Urea and Slurry

89
Q

What is Urea broken down into after application ?

A

Ammonia after application

90
Q

What does the ammonia dissolve into after application ?

A

Soil water and hopefully moves down to roots

91
Q

Under good drying conditions what happens to this water and ammonia?

A

Evaporated as ammonia

92
Q

What is the advice with ammonia?

A

Nit to use urea after may

93
Q

What months is the greatest risk of ammonia volatilisation?

A

May, June, July

94
Q

What must be used for slurry application on holdings with grassland staking rates of 170kg N/ha from grazing livestock manure or above prior to export of livestock manure from the holding?

A

LESS

95
Q

What is the compulsory usage of LESS being introduces on a phased basis:

A

➢ 130 kg N/ha from grazing livestock manure or above prior to export of livestock manure from the holding from 1st January 2024.
➢ 100 kg N/ha from grazing livestock manure or above prior to export of livestock manure from the holding from 1st January 2025.
➢ All slurry produced by pigs on any holding from 1st January 2023.
➢ From 1st January 2023, LESS equipment shall be used to apply livestock manure to arable land or the livestock manure shall be
incorporated within 24 hours.

96
Q

Dairy roadmap 2027:
1-Current Fertiliser N usage kg/ha
2-Current research performance
3-2027 goal

A

1-184 kg/N/ha
2-150 kg/N/ha
3-170 kg/N/ha

97
Q

Suckler calf-to-beef Road map 2027:

1- Percentage of N as protected urea used:
-current
-2027 goal

2- Percentage of slurry applied by LESS:
-current
-2027 goal

A

Q1
-1%
-50%

Q2
-5%
-75%

98
Q

Methods to reduce volatilisation: (4)

A

Band spreading
* Deposited by pipes above the crop canopy

Trailing hose
* Pipes are longer and trail along the ground
* Deposited directly on the soil surface

Trailing shoe
* ‘shoe’ coulter attached to the base of the pipe
* Separates the sward canopy
* Deposited on the soil surface

Shallow injection
* Disc that cuts a slit in the soil
* Slurry deposited in this slit
* Not suitable for many Irish soils – variability in texture,
stone content, topography

99
Q

Highest N loss in order from the highest to the lowest :

A

1- Splash plate 100%
2- Dribble Bar 34%
3- Trailing Shoe 28%
4- Disc- Injector 11%

100
Q

What increases the average available nutrients?

A

Trailing Shoe

101
Q

No slurry should be applied to what index?

A

Index 4

102
Q

Why is Phosphorous required? (5)
Present in hergabe at ?g/kg DM

A
  • Involved in:
    ➢ chemical reactions within the plant
    ➢ plant metabolism/new growth
    ➢ Root and seedling development
    ➢ Plant maturity process and tillering
    ➢ Seed production/ flowering
  • Present in herbage at 2-4 g/kg DM
103
Q

1-What sort of mobility does phosphorus have in soil?
2- Where does P tend to remain in the surface?
3- What measure incorporates it though the soil?
4-When is phosphorus poorly up taken ?
5- What requirements is phosphors taken up in?
6- What has a high affinity of phosphorus ions?
7- What does phosphate bind to?
8-What is the exception of the binding?

A

1* Poor mobility in the soil
2* P tends to remain near the surface
3* Reseeding is a good opportunity to
incorporate it through the soil
4* Poor uptake in cold spring
5* Phosphates are not taken up by plants in
excess of requirements
6* Soils have a high affinity for phosphorus ions
7* Phosphates bind to mineral soils so there is a low risk of leaching
8* Except in peat soils and when you have P
saturation – leached as phosphate

104
Q

What index should you not spread phosphorus on?

A

Index 3 soil range: 5.1-8.0
and Index 4 soil range: >8.0

105
Q

Whats general P fertiliser advice for grazing? (5)

A
  1. Determine P required for soil P build-up
  2. Determine P required for soil P maintenance
  3. Take account of available P in slurry and FYM
  4. Calculate chemical fertilizer P
  5. Determine maximum P allowance and confirm that P fertilizer requirement of the holding is compliant with
    the NAP regulations
106
Q

No slurry should be applied to ** while other land is available on a farm to receive slurry and in compliance with the NAP?
:

A

Index 4

107
Q

What does a P deficiency look like? (5)

A
  • Can be difficult to recognise
  • Weak growth during establishment
  • Subsequent reduced leaf size
  • Lowered grass production
  • Symptoms include stunted, thin stemmed and spindly plants with bluish- green leaves particularly older leaves
108
Q

When are there P losses?
Whats the consequences

A

Over application of P
– Unnecessary costs
– Some soils (peats) are vulnerable to P loss
==
Lost to waterways and has negative effects on water quality through Eutrophication

109
Q

1- Is Potassium essential?
2-When is it needed to compliment N if ?
3-What step is important to measure regularly?
4-What sort of K content in grass is concentrated in cell sap?

A

1* Essential element
2* Needed to compliment N if high production is to be attained
3* Regular soils analysis important as K status can drop rapidly in some soils
4* K content in grass of 25-40 g/kg DM – concentrated in cell sap

110
Q

1-Whats the function of potassium?
2- What’s it involved in?

A

1* Regulates cell water content > controls the loss of water by transpiration through the leaf pores
2* Involved in:
➢ maintaining cell turgor and strengthening the structure of the foliage
➢ sugar formation
➢ root development
➢ transport of metabolites and nutrients within the plant

111
Q

1-What does the requirement of potassium depend on?
2- when is a large amount of K removed?
3-is K readily taken up?
4- what does K supplied by depend on?

A

1-Utilisation
2-A large amount of K is removed in silage
3-K highly mobile – readily taken up
4-K supplied by the soil depends on the soil type

112
Q
  • High levels of K in the herbage will:
A

depress Mg absorption in the rumen esp. in Spring > Mg levels are naturally low at this
time

113
Q
  • Therefore, unless index 1 fertilizer K can be applied:…
A

in autumn to reduce the risk of hypomagnesaemia (Mg deficiency in animals arising from luxury uptake of K by grass
in the spring

114
Q

Is soil index is 3 how much K is in the soil?

A

101-150 mg/l

115
Q

Grazing: available K for grazing @ stocking rate
of 2LU/ha* organic N

A

Index 1- Dairy 90
Index 2- Dairy 60
Index 3- Dairy 30
Index 4- Dairy 0

116
Q

What are symptoms of a K deficiency? (5)

A
  • Grass growth lacks vigour even where N is sufficient
  • Older leaves turn light green as K moves to younger leaves
  • Some scorching of leaf tips may occur
  • Root development is restricted
  • Wilting during drought
117
Q

What is poor competitors of both K and P?

A
  • Clover are poor competitors of both P and
    K
    ➢clover will be affected first
    ➢disappearance from the sward before negative effects are evident in the grass
118
Q

Optium pH ?

A

Above 6.3 (Teagasc target 6.5 pH)

119
Q

What is leached and removed in harvested herbage?

A

CA

120
Q

Surface acidity often occurs in the top ** of
grassland due to **

A

50mm
high rainfall and heavy use of chemical N

121
Q

Is there a best time application for lime?
When can you graze?
If advice is greater than 7.5 tonne/ha then apply:

A

-No best application time – evenly distributed
* Grazing rotation as soon as lime is washed off leaves
* If advice is greater than 7.5 t/ha, apply 7.5 initially and remainder after 2 years

122
Q

What does lime improve?
What is stimulated when its spread?
What does it supply?
Whats the conc of Ca in grass?

A

➢ physical structure of the soil
➢ chemical and biological conditions for uptake of soil nutrients
* Mineralization of nutrients from soil OM is
stimulated
* Supplies Ca for plant growth
(concentration of Ca in grass 4-12 g Ca/kg DM)

123
Q

Whats the optimum pH for white clover?

A

7

124
Q

Whats the optimum pH for cereals?

A

6.5

125
Q

Whats the optimum pH for grass?

A

6.3

126
Q

What does soil acidity reduce?
What does it form?
What is reduced?
What are locked up?

A
  • Reduces earthworm and microbial activity build up of dead material
  • Forms a mat that prevents light penetration to the base of the sward
  • Tiller production is reduced
  • Nutrients are locked up

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