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)
2
Q
Whats the N content g/kg DM?
What does N do?
A
20-50
Drives plant growth , element of AA
3
Q
Whats the P content g/kg DM?
What does P do?
A
2-4
Root development , energy utilisation, cell division
4
Q
Whats the K content g/kg DM?
What does K do?
A
25-40
Maximise N use , sugar formation
5
Q
Whats the 3 main elements that need to be returned to the soil following grazing/silage harvesting
A
Nitrogen
Phosphorus
Potassium
6
Q
What is the most abundant element in the atmosphere and what % is it?
A
Gaseous N
78%
7
Q
Grass requires 2 things for growth:
A
-Nitrate
-Ammonia ions
8
Q
Under 2 cut system how many kg of N is removed?
A
200-500kg
9
Q
15t DM/ha/year requires the uptake of how much N/Ha?
A
450kg/N/ha
10
Q
Whats the average cp% for 15,000kg DM
A
18.75% CP
11
Q
Whats the minimum N/kg/DM required for optimum photosynthesis?
A
30g N/kg/DM
12
Q
N2
A
di-nitrogen gas
13
Q
NO2
A
Nitrite***
14
Q
NO3
A
Nitrate (Nitrate leaching; soil collides negatively charges)
15
Q
N2O
A
Nitrous oxide
(potent GHG)
16
Q
NH3
A
Ammonia
(Ammonia Volatilization)
17
Q
NH4+
A
Ammonium***
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
19
Q
How does nitrate enter the plant?
A
Passively- directly stored in the leaf tissue.
20
Q
When plant roots uptake Nitrate what is released by the plant root?
A
OH-
21
Q
What can be converted directly into the root?
A
Ammonia
22
Q
When plant roots uptake Ammonium what is released by the plant root?
A
H+
23
Q
Definition: Fixation
A
- fixation is the process of converting dinitrogen gas (N2) to chemically reactive forms
24
Q
Definition: Mineralisation
A
- Microorganisms decomposed OM into easily available N forms to plants
25
Definition: Nitrification
* microbial process by which ammonia is converted to nitrite and nitrate
26
Definition: Leaching
* The nitrate is soluble and is leached easily when excess water percolates through the soil
27
Definition : Plant assimilation
Plant roots take up nitrogen in primarily the nitrate or ammonium forms
28
Definition : Denitrification
Denitrification is the process which microbes convert nitrate to nitrogen gas
29
Definition: Volatilisation
* Ammonium in the soil is converted to ammonia, which is lost as a gas
30
Definition: Immobilisation
* nitrate and ammonium are taken up by soil organisms and
therefore become unavailable to crops
31
LOOK OVER THE N CYCLE
32
Response to nitrogen:
15-25 kg DM/kg N=
Up to 250-350 kg/ha
33
Response to nitrogen:
5-15 kg DM/ Kg N=
350-450 kg/ha
34
When does N uptake increase?
When does it peak?
March and April
Peaks at 3.5 kg N/ha/day during late May
35
What % of fertiliser N is taken up by grass?
70-80%
36
The average grass growth response is *** at an application rate of between ****
-17 kg DM/ha per kg N
-150-200kg N/ha
37
What was the nitrogen response as N rate increased?
Reduced
38
N intake :(4)
-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)
39
What does N deficiency look like in grass?
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
40
List sources of N: (6)
Where must this be accounted?
* 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)
41
What % of OM does soils contain?
How much organic N?
5-20%
These contain large stores of organic N (5000+ kg/ha)
42
What % is available to the grass plant in any year?
-2%
-98% unavailable
43
Average background N release how much kg N/ha?
124kg
(40-330kg)
44
What renders available N?
What is increased following ploughing?
* Constant turnover renders some N available
* Mineralization is increased following ploughing
45
Where is the highest available kg/N/ha/yr?
220 kg N/Ha/Yr
46
Where is the lowest available kg/N/ha/yr?
Drumlins
47
Where is the average available kg/N/ha/yr?
140
48
Lower quantities of N are found in what type of soils?
shallow topsoil with lighter arable soils
49
Higher quantities of N are found in what type of soils?
deeper topsoil with heavier soils e.g. long-term grassland
50
What is also important when it comes to availability of N from grassland soils in Ireland?
-Soil OM
-Drainage
51
When does the highest N release from soil occur?
Late spring and early autumn when soil temperature and moisture levels are favourable
52
During winter months :
Higher than general estimates of 200 to 250 g/ha/day which would be sufficient to produce :
6.5 to 7.5 kg/DM/ha/day
53
What % of N consumed in herbage is excreted
depending on the type and class of animal and
diet offered
75-90%
54
What animals utilize the least and the most :
-Beef Store cattle-Least
-Dairy cows- most
55
Whats important to note about dairy cows and N?
While dairy cows utilize the most of N consumed, they are still very inefficient users of N.
56
How much N is in dung? and how much is in urine?
Are they both available?
Approx. ¼ of N is in the dung (not immediately
available) and ¾ in the urine (available)
57
PRG contains high levels of ?
RDP
Rumen Degradable Protein - 81%
58
What animal has the highest N excretion rate (apart from dairy cows)
50kg
59
Whats the aim of the EU nitrates Directive?
to prevent pollution of surface waters and groundwater from agricultural sources and to protect and improve water quality.
60
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?
-89
-80
-92
-106
-Milk yield /annum (for 3 preceding years )
61
Average DM% cattle slurry on irish farms is ?
6.3%
(0.4-11.9%)
62
Watery slurry or parlour washings has what sort of DM content?
Low DM content
63
Increase DM=
Increased nutrient value
64
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?
* 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
* CAN (calcium ammonium nitrate) supplies nitrate & ammonium What % N?
27% N
66
* Urea following application is converted to ammonium what % N?
46%N
67
How much N per acre?
* Units/acre x 1.25 = kg/ha
* 50 kg or 500 kg bags typically
68
Example: 2.5 ha field requiring 30 kg N/ha
* 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
Urea vs CAN:
Urea= straight urea
CAN= goes into soil as ammonium or nitrate
70
What pastures should you fertilise first?
– 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
What degrees is the minimum for grass growth?
5 degrees
72
What cm is low?
5cm or less
73
What cm is medium, high?
10cm and over
74
* Which pastures to fertilise with urea?
– 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
How much urea?
– 28.8 kg N/ha (about 0.5 bags/ac) at GRANGE
– BUT, response depends on soil, pasture, management
76
When to apply urea?
– While 5-cm soil temperature is above 5°C and increasing
i.e. when most pastures are starting to grow
77
Whats the spring N recommendation?
60 kg N/ha split 33:66 between
February and March
Nitrogen response reduced as N rate increased
78
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?
❖ 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
Effect of season on herbage DM response to
fertiliser N- when do you get the best response ?
May - 15-25
June- 30-40
July- 20-30
Kg DM/kg N
80
If N is not being taken up by the plant, where does it go?
* 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
Nitrate Leaching:
What is a disadvantage ?
* 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
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.
50-53%
83
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:
90-85%
84
Denitrification SMD
Where does it occur?
What detach?
What releases?
* Heavy waterlogged soils (SMD -10)
* Soil becomes depleted of oxygen
* Bacteria detach O2 from nitrate (NO3)
* Release N2O and N2 gases
85
Zones A,B,C (Donegal and Leitrim),D(Cavan and Monaghan)
Whats the Storage period?
A- 16 weeks
B-18 weeks
C- 20 weeks
D- 22 weeks
86
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:
– 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
All holdings producing soiled water must have minimum 31 days storage from
1st December 2024 with exception
of winter milk producers where storage must be in place by 1st December 2025
88
What % of Ammonia emissions come from agriculture?
Whats ammonia associated with ?
-99%
-Application of Urea and Slurry
89
What is Urea broken down into after application ?
Ammonia after application
90
What does the ammonia dissolve into after application ?
Soil water and hopefully moves down to roots
91
Under good drying conditions what happens to this water and ammonia?
Evaporated as ammonia
92
What is the advice with ammonia?
Nit to use urea after may
93
What months is the greatest risk of ammonia volatilisation?
May, June, July
94
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?
LESS
95
What is the compulsory usage of LESS being introduces on a phased basis:
➢ 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
Dairy roadmap 2027:
1-Current Fertiliser N usage kg/ha
2-Current research performance
3-2027 goal
1-184 kg/N/ha
2-150 kg/N/ha
3-170 kg/N/ha
97
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
Q1
-1%
-50%
Q2
-5%
-75%
98
Methods to reduce volatilisation: (4)
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
Highest N loss in order from the highest to the lowest :
1- Splash plate 100%
2- Dribble Bar 34%
3- Trailing Shoe 28%
4- Disc- Injector 11%
100
What increases the average available nutrients?
Trailing Shoe
101
No slurry should be applied to what index?
Index 4
102
Why is Phosphorous required? (5)
Present in hergabe at ?g/kg DM
* 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
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?
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
What index should you not spread phosphorus on?
Index 3 soil range: 5.1-8.0
and Index 4 soil range: >8.0
105
Whats general P fertiliser advice for grazing? (5)
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
No slurry should be applied to **** while other land is available on a farm to receive slurry and in compliance with the NAP?
:
Index 4
107
What does a P deficiency look like? (5)
* 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
When are there P losses?
Whats the consequences
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
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?
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
1-Whats the function of potassium?
2- What's it involved in?
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
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?
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
* High levels of K in the herbage will:
depress Mg absorption in the rumen esp. in Spring > Mg levels are naturally low at this
time
113
* Therefore, unless index 1 fertilizer K can be applied:...
in autumn to reduce the risk of hypomagnesaemia (Mg deficiency in animals arising from luxury uptake of K by grass
in the spring
114
Is soil index is 3 how much K is in the soil?
101-150 mg/l
115
Grazing: available K for grazing @ stocking rate
of 2LU/ha* organic N
Index 1- Dairy 90
Index 2- Dairy 60
Index 3- Dairy 30
Index 4- Dairy 0
116
What are symptoms of a K deficiency? (5)
* 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
What is poor competitors of both K and P?
* 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
Optium pH ?
Above 6.3 (Teagasc target 6.5 pH)
119
What is leached and removed in harvested herbage?
CA
120
Surface acidity often occurs in the top *** of
grassland due to ***
50mm
high rainfall and heavy use of chemical N
121
Is there a best time application for lime?
When can you graze?
If advice is greater than 7.5 tonne/ha then apply:
-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
What does lime improve?
What is stimulated when its spread?
What does it supply?
Whats the conc of Ca in grass?
➢ 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
Whats the optimum pH for white clover?
7
124
Whats the optimum pH for cereals?
6.5
125
Whats the optimum pH for grass?
6.3
126
What does soil acidity reduce?
What does it form?
What is reduced?
What are locked up?
* 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
