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Subjects · Leaving Cert Agricultural Science

Leaving Cert Agricultural Science: Grass growth & grazing

How often Grass growth & grazing comes up on the Agricultural Science papers, every year it was asked, and questions to try.

HL Asked on 4 of the last 5 Higher Level papers, most recently in 2024. most years

OL Asked on 3 of the last 5 Ordinary Level papers, most recently in 2025. most years

Grass growth & grazing, Higher Level(8 marks)

Quick ones on Grass growth & grazing.

(a)Sward height 10 cm, residual 4 cm, about 250 kg DM/ha per cm. What is the grass cover?
  1. 2,500 kg DM/ha
  2. 1,500 kg DM/ha
  3. 1,000 kg DM/ha
(b)Which grazing system gives stock a fresh area of grass each day using a movable wire?
  1. Zero grazing
  2. Set stocking
  3. Strip grazing
(c)At about what leaf stage is perennial ryegrass ideally grazed?
  1. About the three-leaf stage
  2. About the six-leaf stage or later
  3. About the one-leaf stage
Show the answers

(a) 1,500 kg DM/ha

(b) Strip grazing

(c) About the three-leaf stage

Your turn: Higher Level questions on Grass growth & grazing.

Higher Level

Asked on 4 of the last 5 Higher Level papers, most recently in 2024. most years

Every paper, year by year

YearWhere it came up
2025Not asked
2024Q3a, Q3b, Q14c, Q14d
2023Q17
2022Q13, Q16
2021Q13, Q15, Q16d

Links open the State Examinations Commission’s paper for that year.

More Grass growth & grazing questions

Grass growth & grazing, 3 marks

Why is grazing grass too tightly below the target residual harmful?

  1. It makes the grass flower and set seed sooner
  2. It raises the soil pH around the plants
  3. It removes stored reserves, slowing regrowth
Show the answer

It removes stored reserves, slowing regrowth

Grass stores sugars in the base of the tillers. Grazing too low removes these reserves and the leaf area needed for regrowth.

Grass growth & grazing, 3 marks

Why does leaving high residuals after grazing lower quality in later rotations?

  1. The soil becomes compacted
  2. Stemmy, dead material builds up in the sward
  3. The grass stops tillering completely
Show the answer

Stemmy, dead material builds up in the sward

Grass left behind goes stemmy and dies back, lowering digestibility. Cows then reject it and quality falls further.

Grass growth & grazing, 2 marks

In paddock grazing, what is the rotation length?

  1. Days taken to graze all paddocks once
  2. Days a cow spends in one paddock
  3. Weeks between reseeds
Show the answer

Days taken to graze all paddocks once

Rotation length is the time from grazing a paddock to grazing it again. It is shortened when growth is fast and lengthened when growth slows.

Ordinary Level

Asked on 3 of the last 5 Ordinary Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q4
2024Q1, Q14
2023Not asked
2022Q15, Q16
2021Not asked

Links open the State Examinations Commission’s paper for that year.

More Grass growth & grazing questions

Grass growth & grazing, 2 marks

In a paddock grazing system, the animals?

  1. Graze the whole farm freely all year
  2. Stay indoors all summer
  3. Graze one section at a time, then move on
Show the answer

Graze one section at a time, then move on

Rotating around paddocks gives each area time to regrow. This gives better grass use and quality than set stocking.

Grass growth & grazing, 3 marks

About how many leaves should a ryegrass tiller have when it is grazed?

  1. About six
  2. About three
  3. One
Show the answer

About three

A ryegrass tiller holds about three live leaves. Grazing at this stage gives the best mix of yield and quality before older leaves die.

Grass growth & grazing, 2 marks

In which month is grass growth usually fastest in Ireland?

  1. May
  2. December
  3. February
Show the answer

May

Warm soil, long days and good moisture give peak growth in late spring. Growth almost stops in winter when the soil is cold.

Other Agricultural Science topics

All of Leaving Cert Agricultural Science