Grass Flashcards
Benefits of red clover in the diet
Can improve the fatty acid content of milk, but don’t feed to sheep 6-8 weeks pre/post mating
What is the grazing residual of red clover?
6cm
What is the inclusion rate of RC?
4kg
Benefits of a clover sward?
Produces more milk with a higher quality intake
How much N can WC fix?
140kg N/ha/year
What is the life expectancy of clover?
5 years
How much clover do you sow when over-sowing?
5kg/ha with one bag of 0:70:30 but if it is an existing clover sward then only sow 2.5kg/ha
In what soils is there maximum clover productivity?
Medium to free draining loam soils
Every 1 tonne of grass utilised increases profitability by how much on dairy farms?
€181/ha on dairy farms and €105/ha on dry stock farms
What is the DM intake of a 600kg cow per day?
15-19kg
How long do cows spend grazing?
7-9 hours per day
What is the rotation length in a leader follower system?
4-5 days
How much CP is in grazed grass?
180-250g/kg/DM
Best indication of pasture quality?
Organic Matter Digestibility, used to calculate GE content. Higher the OMD, higher the UFL
What is the DMD of Autumn grass?
80%
What is the substitution rate for grass for every 1kg DM of grass silage fed?
0.9kg DM
What is the optimum proportion of maize silage in the diet?
33%
What benefits does maize silage have in the diet?
Good energy, increased DMI
What are the maize nutrient requirements?
180kg/ha potash, 40kg/ha of phosphate and 150kg/ha of N
Overgrazing
Post grazing sward height of less than 3.5cm
3.5-4cm represents how many kg DM/ha?
0.50kg DM/ha
What is the grass organic matter digestibility (OMD) used for?
Energy content/UFL/UFV value
What is the water soluble carb (WSC) content of grazed grass?
150-200kg DM
Length of true stem in PRG
3cm
Length of the final grazing rotation of the year?
40-45 days
Average farm cover in late November?
550-600kg DM/ha @ 2.5 LU/ha
60:40 autumn grassland plan?
60% grazed by 1st November
Spring turnout farm cover?
900-1000kg DM/ha
Complete 1st rotation by what date?
1st April to 15th April
3 pieces of info the spring rotation planner needs?
Date of turnout, date of finished 1st rotation, and area of ground to be grazed
Forward creep grazing of lambs can increase weaning weight by?
2kg
Target weight gain of a lamb at grass post-weaning?
150g/day
Issue of over-lush grass with horses
Inefficient use and risk of laminitis
Consequences of selective grazing?
Patchy swards, weeds, overgrazing, and nutrient depletion
How much of long established horse pasture is grazed?
10%
How to tackle patchy swards?
Mixed grazing and over-sowing
How much N is applied to horse pasture?
25-30kg N/acre
Rest period for horse grazing benefits?
Decrease worm burden
Target pH of horse paddocks?
6-6.5
Sheep more favourable in mixed grazing with horses because?
Less damage during wet weather
Why is harrowing carried out in the spring?
Remove dead material from the base of the sward
Chain harrowing in autumn purpose?
Break up dung patches and increase breakdown rate
What depth does shallow compaction go down to?
10cm
Research in Teagasc suggested what as a strategy to permit early spring grazing?
Allow cows restricted access time to grazed pasture daily
In early grazing, what sort livestock should be let out first?
Lighter cattle should be let out first
Grass DM requirement of an animal?
2%
Target number of days: April-June, July-August, September-closing
April-June = 12-14 days, July-August = 16-18 days, September-closing = 25 days
3 elements in KT grassland management programme?
Soil fertility, reseeding policy, and grass utilisation
% of mid-season lambs to be drafted by end of September?
70-85%
How long should it take to graze out a paddock during the main grazing season?
5 days
Rest period length for paddocks over the winter months?
120 days
Grass DM that a lactating ewe will eat daily?
3.2kg DM/day
Characteristics of RC?
Short life span, erect growth habit, good winter hardiness
What is the function of PPO (Polyphenol Oxidase)?
Inhibition of post-harvest proteolysis by inhibiting activity of the plant proteases in the silo
How many tillers present in high sward density?
30,000
Clover in horse pasture?
0%
Laminitis definition?
Inflammation and weakening of the laminae that bonds the hoof wall to the pedal bone in the hoof – Spring and Autumn high risk periods
What is in ragwort to make it poisonous?
Pyrrolizidine alkaloids – causes inhibitions of normal repair in the liver and inhibits its regeneration
What is the % of silage in the feed budget in beef and dairy farms?
Beef = 24-38%, Dairy = 19-25%
Buffering capacity definition?
The equivalents of acid per unit DM required to lower crop pH from 6 to 4
Typical buffering capacity in grass?
250-350 mEq/kg
What is the DM content of crimped grain?
60-70%
What is the DM content of urea-treated grain?
65-72%
Why is 85% of maize grown under film?
Increases temperature & DM yield
When should silage be tested?
At least 6 weeks after ensiling
What is the annual average of clover that should be in the sward?
20-25%
Why is RC more drought resistant than WC?
RC has tap roots
How much N can RC fix?
200kg of N/ha/year
How much N can WC fix annually?
100-150kg of N/ha/year
A PRG/RC sward can yield how many tonnes of DM per year?
11-13t DM/year
What is the cost of producing 1t of usable silage DM at a yield of 5t?
€125 for 1st cut and €140 for 2nd
What is forage preservation based on?
Lactic acid fermentation under anaerobic conditions
What is the purpose of epiphytic lactic acid bacteria?
Fermentation of water soluble carbohydrates in the crop to lactic acid and acetic acid
As pH is decreased…
Spoilage organisms are inhibited
What are the 4 phases of the ensiling process?
Aerobic phase, fermentation phase, stable phase, and feed-out phase
How long does the anaerobic stage of the ensiling process last?
Few hours
What will develop if fermentation is successful?
Lactic acid bacteria
What is the pH range of silage?
3.8-5.0
What are the 2 phases of feed out?
Degradation of preserving OA’s and rise in pH/activity of spoilage organisms
What can DM increase be achieved by?
Delaying harvest and wilting
What helps to accelerate loss of water from a plant?
Disruption of the cuticle
What are the primary fermentable substrates in temperate grasses?
Glucose, fructose, sucrose, and fructans
Disadvantages of RC?
Unsuitable to intensive grazing, yield declines over time, can lead to bloat in ruminants
When sowing a RC/PRG mix what should the ratio in the seed mix be?
3:1
Why is it important to encourage stolon growth throughout the year?
To ensure high survival rates over the winter
How much WC should be included per ha?
4.63kg/ha
How much grass is sown per ha?
14kg/ha for diploid and 16kg/ha for tetraploid
If a plant has a caespitose growth habit, what does it mean?
Grows in tufts
What type of growth habit does WC have?
Stoloniferous
What is the usual inclusion rate of WC in a seed mixture?
1kg/ha
How much clover would you usually find in a permanent pasture in Ireland?
Rarely more than 5%
For high clover establishment, how much will need to be incorporated in a seed mix?
3-4kg/ha
In relation to WC, what are the characteristics of varieties with medium sized leaves?
Moderate stolon density and suitable for frequent close grazing
Characteristics of large leaves?
Longer petioles and fewer stolons, suitable for lax rotational grazing
When does WC have a lower leaf photosynthesis than grasses?
Spring
When does WC have a higher leaf photosynthesis than grasses?
Summer
Over the summer period, which animals should be grazed on WC ground?
Priority stock
When does WC rebuild its stolon/leaf reserves?
Autumn
What is the recovery period over the winter for WC swards?
100-150days
What would the CP content of a WC/PRG sward be?
21%
Advantages of WC?
Increased intakes and mineral content
Disadvantages of WC?
Persistence issues, bloat, difficult to control docks
On a heavy farm what should the grazing targets be?
Turnout late Feb/early March, 30% grazed by March 10th. 60% grazed by March 27th and 100% grazed by mid-April
Target average farm cover during main grazing season?
450-600kg DM/ha
Stocking rate for adequate feeding of cows at pasture?
4.5 cows/ha
What % of leaf should you maintain in the sward ahead of the cows?
65%
Stocking rate of 2.5 cows/ha how much ground can be taken off for silage?
45-50%
Priority when supplementing grass?
Maximise production
Advantages of mixed grazing?
Increases pasture utilisation and reduces pasture burden
What is the maximum ratio of field sides in grazing systems?
4:1
% N in atmosphere?
78%
Type of plant that has the ability to fix atmospheric N?
Legumes
What type of bacteria form a symbiotic relationship with legumes?
Rhizobium
What is N gas converted to in the root nodules of the plant?
Ammonia (NH3)
What form of N do bacteria provide for the legume plant?
Ammonium
Benefit of symbiotic relationship for bacteria?
Legume provides them with CHO for energy
What is growth in legumes directly related to?
Rate of N fixation
- What height should grass be cut to when measuring using a quadrat and shears?
a. 4cm
During periods of continuous rain what should you estimate grass DM to be?
12-15%
DM in 1st rotation in spring?
18-19%
DM during drought?
22-23%
For high clover establishment, how much will need to be incorporated in the seed mix?
3-4kg/ha
What grazing technique should be employed on WC ground in spring to ensure grazing quality for later in the season?
Frequent rotational or continuous grazing
Why is it important to maintain a well-cushioned turf?
For horses to exercise, particularly young stock
What happens to overgrazed areas?
They become depleted of nutrients
After rejuventation, how much of a horse pasture will be grazed?
20-30%
With horses, when should grazing occur?
Just before the rate of grass leaf growth declines
What is the carrying rate of high quality grassland?
3-4 light horses (400kg)/ha, 4-6 smaller ponies/ha
How much do heavy breeding mares (700-800kg BW) require on good temperate summer grassland?
0.7-10ha/mare and foal
When following cattle, how much should be allocated to a mare and foal?
1.5-2.0ha
Rotational grazing, cutting excess herbage and N input of 80-150kg N/ha can support how many horses?
2-2.5 growing horses/ha
Why should hay be made from paddocks that have been previously grazed by horses?
Parasite control
Compare tetraploid to diploid varieties of PRG
Tetraploid have larger tillers, lower tiller densities, lower DM content, higher WSC, are susceptible to poaching
What is the average farm size in Ireland?
32ha
Grassland accounts for what % of total land use in Ireland?
59%
Leys advantages
soil fertility, weed, pest and disease control
Common sown grasses
PRG, IRG, Cocksfoot, Timothy, Meadow Fescue
PRG Characteristics
Rapid establishment, good tillering, dense sward, high DM yields and good digestibility, excellent production response to fertile conditions and fertiliser N
Heading Date
Approximate date around which 50% of reproductive tillers will produce seed heads
What 3 species account for nearly all of the agricultural grass/clover seed sold in Ireland
PRG, IRG, WC
3 seed categories based on heading dates
early, intermediate, late
Early seed
heads in first half of May, use of this declined due to stemmy regrowth in summer
Intermediate seed
head in second half of May, produce high quality silage cuts, good sward density
Late seed
head in first half of June, high tiller density, well suited to long term grazing pastures, good quality silage cuts in early June
Diploid
high tiller density, higher DM%, slightly lower DMD, lower yielding
Tetraploid
low tiller density, lower DM%, high DMD, higher yielding
Vigorous swards
a sward that can grow out of season, have a high tiller density and provide adequate grass production when required
Reseeding advantages
increase the productivity, higher level of regrowth, respond better to applied N, improve grass quality, reduce silage requirements
Temperature requirements for autumn reseeding
6oC for grass seedlings/ 8oC for clover seedlings
What month is the most suitable for Autumn reseeding
August
Soil fertility
the quality of a soil that enables it to provide nutrients in adequate amounts and in proper balance for the growth of specific plants or crops
Phosphorus (P) function
Essential for root development and sward establishment
Potassium (K) function
Controls the loss of water by transpiration through the leaf pores, sugar formation and root development, and transport of metabolites and nutrients within the plant
Optimum pH for grassland
pH 6.3
Conventional reseeding method
spray off old sward, shallow ploughing (<15cm), lime, land level, fertiliser, sow the seed, roll
Alternative reseeding methods to conventional
discing, one pass, direct drilling (stitching in, undersowing, oversowing)
Tillering
development of a plant that is similar to the parent plant from a bud that is formed as each new leaf appears in the leaf axial
A tiller normally develops in the axial of the first leaf at what leaf stage?
3-4 leaf stage
Cost of reseeding 2023
€540/ac
3 main elements that need to be returned to the soil following grazing/harvesting
N, P, K
Nitrate poisoning
caused by high nitrate levels during a flush of growth after a dry period, particularly in late autumn or winter. Build up in herbage when nitrate is taken up by plant faster than it can be converted into protein
Livestock manure loading shall not exceed how many kg organic N/ha/year
170kg organic N/ha/year
How much fertiliser N is taken up by grass
70-80%
Sources of N
Atmospheric deposition (12 kg/ha/year), Background release (soil organic N), Clover (100-150 kg/ha/year), Animal excreta, FYM/slurry, Fertiliser
Average DM% cattle slurry on Irish farms is…
6.3% (0.4-11.9%)
EU Nitrates Directive - National Action Programme (NAP) regulations, statutory instrument (SI) 31 of 2014 Aim to?
prevent pollution of surface waters and groundwater from agricultural sources and to protect and improve water quality
LESS
Low Emission Slurry Spreading
Concentration of Ca in grass
4-12 g Ca/kg DM
Soil acidity
Reduces earthworm and microbial activity, build up of dead material, tiller production is reduced, nutrients are locked up
Intensive and semi-intensive grasslands represent what % of total land use
2%
Grassland accounts for what % of Irish agricultural land area
92%
Why is knowing soil temp important?
To know when the plant is growing so that N fertilisers can be applied to promote growth at the opportune time
Hybrid Ryegrass
IRG x PRG, appearance reflect one parental type, out of season growth IRG, sward density PRG, more persistent than IRG
Reasons to reseed for grazing
10-20% more productive tillers, longer growing season, rapid regrowth, higher palatability/digestibility
Reasons to reseed for silage
higher grass quality, easier to preserve (higher sugar content), faster recovery, consistently higher yields
Tiller deaths greatest when?
May/June
Tiller numbers greatest when?
March-May and July-August
Average leaf longevity for PRG is…
33 days
What is the most abundant element in the atmosphere
Gaseous N (78%)
Minimum g N/kg DM required for optimum photosynthesis
30 g N/kg DM
15t DM/ha/year requires the uptake of how many kg N/ha
15,000 kg DM @ avg. 18.75% CP (18.75 x 16% protein = 3% N) = 450 kg N/ha
Nitrogen banding: kg N/year for band 1, 2, and 3 based on milk yield p.a.
Band 1 - 80kg N/year for <4,500kg milk yield p.a.
Band 2 - 92kg N/year for 4,501-6,500kg milk yield p.a.
Band 3 - 106kg N/year for >6,500kg milk yield p.a.
CAN has what % N?
27% N
Urea has what % N?
46% N
Grazing height for cattle
5-8cm
Grazing height for sheep
3-6cm
What % of ammonia emissions come from agriculture?
99%
K content of grass in g/kg DM
25-40g/kg DM
Crude protein content of grass
~18.75%
What is the Irish land area in hectares?
6.9 million
AAU stands for what?
Agricultural Area Utilised
Grassland accounts for what percent of the world’s surface?
40%
Land use change is…
Very slow
What is the temperature range in Ireland?
9oC to 10.5oC
What is the variation of the length of rainfall in Ireland?
200-270 days
In relation to Food Wise 2025, what target are dairy farmers looking to meet?
Increasing grass utilisation to 10t/ha
What is the variation of annual rainfall in Ireland?
750-1450mm
In what month does grass growth almost cease?
November
What is the annual DM yield in Ireland?
11-15t/ha
What percent of global land use does total grassland make up?
25%
What percentage of global grassland is located in Europe?
13%
Intensive and semi-intensive grasslands represent what percentage of total land use?
2%
Species-rich grassland began forming approximately how many years ago?
15-13,000 years ago
Grassland accounts for what percentage of land use in Ireland?
59%
On average, how many hours of sunshine does Ireland receive each year?
1400-1700
In Ireland’s coastal areas, how many days of frost occur on average?
<25
Topography governs what aspect of soil?
Position on the landscape
Permeability refers to soil’s ability to:
Allow water to pass through
What is the annual profitability variance between well-drained and poorly drained soils in Ireland?
28k
What percentage of national greenhouse gases did Irish agriculture contribute in 2021?
37.5%
Ireland aims to reduce greenhouse gas emissions by what percentage by 2030?
25%
Grassland comprises what percentage of agricultural land in Ireland?
90-92%
How much were Irish dairy exports worth in 2021?
5 billion
The dairy sector accounts for what percentage of agriculture-related emissions in Ireland?
40%
The dairy sector uses approximately what percentage of all chemical nitrogen?
50%
Approximately how many days is Ireland’s grazing season?
200-300+
Annual dry matter yield for grassland in Ireland ranges between
11-15t/ha
Biomass is defined as:
Weight of living organisms at a specific time
How long does a short-term ley last?
1-2 years
How many years is a medium-term ley?
3 years+
Permanent pasture is defined as land that has been under grass for at least how many years without other crops?
5 years
A ley is made up of grass and what other plant?
Legumes
Leys gained popularity around which historical period?
World War II
Ireland is required to maintain what minimum percentage of permanent grassland?
> 5%
How many species of volunteer grasses are found in Ireland?
100
Westerwolds and Multiflorum are species of which type of grass?
IRG
Perennial Ryegrass (PRG) makes up what percentage of grass seed sales in Ireland?
95%
The heading date is defined as the date when what percentage of reproductive tillers produce seed heads?
50%
Which category of heading date is the most popular?
Late (84%)
Grass ploidy refers to the number of what in the cell nucleus?
Chromosomes
PRG have flattened spikelets containing how many florets?
8-12
Italian ryegrass only lasts approximately how many years?
3
What weight in kg of PRG seeds were imported?
3,000,000kg
In regards to tetraploid vs diploid, which of the following has a higher DM?
Diploid
What does DUS stand for?
Distinct, Uniform, and Stable
What does VCU stand for?
Value for Cultivation and Use
Diploids have how many chromosomes, and Tetraploids have how many?
2=Diploid
4=Tetraploid
For a grass variety to make the national list, it must be how much better than the existing variety?
50%
What percentage of land is reseeded annually?
2-3%
What is the target turnaround time for reseeding?
60 days (8-9 weeks)
How many months does it take for a sward to fully establish?
11 months
What percentage of PRG should you aim for in a sward?
60%
Creeping bentgrass has only what percent production potential of PRG?
75%
By what percent does milk output increase per hectare after reseeding compared to permanent pasture?
8%
Autumn reseeding takes longer for grass to establish; how long does it take?
8-10 weeks compared to 4-6
What does an embryo contain?
Tissues that develop into the new seedling plant
What is the Coleorhiza?
A protective covering for the primary root
How deep should you plough when reseeding?
15cm
When direct drilling, what space should you leave between each grass slot?
2-5 inches
Which reseeding method does not require spraying off with glyphosate before reseeding?
Chemical application of diquat to suppress existing sward (diq)
In kg, how much seed is recommended to sow per hectare?
35kg/ha
What is the maximum amount of tetraploids you should use with your silage mixture?
40%
What is the maximum amount of tetraploids you should use with your wetland mixture?
15-20%
What is the maximum amount of tetraploids you should use with your dryland mixture?
35-50%
PRG seeds germinate within how many days if conditions are correct?
5-10 days
Passive uptake of water takes place within how many hours?
12-24 hours
How many days after planting does tall fescue begin to show?
0-6 days
At what depth should a seed be buried to emerge successfully?
1-2cm
Tillering is the development of a new plant from a bud formed where?
Leaf axial
Which of the following is a factor affecting tiller production?
Defoliation
How many leaves should perennial ryegrass (PRG) have at the time of grazing?
3 leaves
What type of root system does perennial ryegrass (PRG) have?
Fibrous root system
Which of the following is a pest commonly found in reseeding?
Leatherjackets
Which element is removed in the highest amounts from grass?
Potassium (K), second only to Nitrogen (N)
Where is potassium primarily concentrated within the grass plant?
Cell sap
What is the maintenance requirement of phosphorus (P) for first-cut silage and hay in soils with index levels 1-3?
20kg/ha
What is the maintenance phosphorus (P) requirement for second-cut hay and silage?
10kg/ha
What is the ideal grassland stocking rate?
170kg/ha
Good fertile soils should have a pH of approximately?
6.2
What is the optimum pH target for grassland, according to Teagasc?
Above 6.3, with a target of 6.5
When does surface acidity in grassland typically occur?
High rainfall and heavy use of nitrogen (above 55mm)
What is the concentration range of calcium (Ca) in grass?
4-12 g/kg DM
The optimum pH for cereal crops is?
6.5
The optimum pH for white clover is?
7.0
What type of bacteria do legume plants provide for energy?
Carbohydrate (CHO) bacteria
What is the typical concentration of phosphorus (P) in herbage?
2-4 g/kg DM
What is fixation?
Conversion of dinitrogen gas to chemically reactive forms
What percentage of fertiliser nitrogen (N) is typically taken up by grass?
70-80%
What percentage of nitrogen consumed in herbage is excreted?
75-90%
When should you apply urea?
When the temperature is above 5°C and increasing
What is leaching?
The process by which nitrate is leached easily when excess water percolates through the soil
What is the function of potassium (K) in plants?
Regulates cell water content
What is the optimum soil pH level for grassland?
At or above 6.3
