Lecture 2: Land use and yields

Question 1

What is the main purpose of growing grass and forages?

Answer 1

• Feed: Milk and meat production

- Living space: Grazing and resting

Question 2

What are sub purposes of growing grass and forages?

Answer 2

• Quality and / or taste of endproduct
• Animal welfare
• Animals need fiber in their diet
• Relatively cheap source
• Living on grass is a special feature of ruminants
• Grass can grow in soil and conditions where no human food will grow

Question 3

What is the fourth stage of grass growth called?

Answer 3

• Dying off = senescence

Question 4

Describe stage 1 of grass growth

Answer 4

• vegetative stage
• Photosynthesis
• Energy can be stored in the roots of the plant
• LAI - leaf area index = The one-sided green leave area per unit ground surface area
• Growing point is close to the ground –> not easily eaten or mowed

Question 5

Describe stage 2 of grass growth

Answer 5

• Elongation
• Internode elongation, important for timing of
  grazing/mowing, so as not to destroy the
  growing tip
• Grass tips contain fatty acids: linoleic acid

Question 6

Describe stage 3 of grass growth

Answer 6

• Generative stage before flowering
• Floral induction: A response to critical temperature regimes, daylengths, and necessary leaf blade area for sensing these climatic variables
  1) low-temperature induction called vernalization, in growing point
  2) photoperiodic induction, in the leaves

Question 7

How are flowerheads described?

Answer 7

• According to the arrangement of a special floral unit, namely the spikelet
• A spikelet consists of one or two flowers and two basal membranes
• The spikelet is attached to an unbranched axis called the rachilla

Question 8

What is photosynthesis?

Answer 8

• A system to transform light into energy
• Happens in chloroplasts with green pigment (chlorophyll)
• Carbon dioxide + water + sun light energy ——-> sugars + water + oxygen
  6 CO2 + 12 H2O ——-> C6H12O6 + 6 H2O + 6O2

Question 9

Environmental influences on grass growth?

Answer 9

Temperature: optimal temperature depends on the crop

• Light intensity: light saturation occurs at some point
• Carbon dioxide: the most commonly limitating factor

Question 10

What is plant respiration?

Answer 10

• Living cells respire
• Aerobic respiration: the chemical reaction to release
  energy from glucose. It is called aerobic because oxygen from the air is also needed
• glucose + oxygen → carbon dioxide + water (+ energy)

Question 11

What are the key elements of photosynthesis?

Answer 11

• Produces sugars from light energy
• Stores energy
• Occurs only in cells with chloroplasts
• Oxygen is produced
• Water is used
• Carbondioxide is used
• Requires light

Question 12

What are the key elements of respiration?

Answer 12

• Burns sugars for energy:
       For maintenance
       For growth= accumulation of dry matter
• Energy is released
• Occurs in most cells
• Oxygen is used
• Water is produced
• Carbon dioxide is produced
• Occurs in dark and light

Question 13

What is gross photosynthesis?

Answer 13

• Total amount of CO2 fixed by the plant

Question 14

What is respiration (short definition)

Answer 14

• Amount of CO2 lost from metabolic activity

Question 15

What is net photosynthesis?

Answer 15

• net amount of primary production after the costs of plant respiration are included
  • Net photosynthesis = Gross photosynthesis -Respiration

Question 16

What is the growing season of grass like?

Answer 16

• Spring
– Sunlight awakens the plant, and soil organisms
– Plant roots search the ground for nitrogen and water – Aerobic organisms also respire, a process also known as ‘mineralisation’, e.g. making nitrogen available
– Slow start, than rapid increase
• Summer
– Grass growth peaks in May
– Dip in June/July
– 2nd peak, not as high
• Autumn
– Growth slows down, stops in Nov.
• Winter
– Resting period, very low respiration

Question 17

Less fertile and dry soils are suitable for:

Answer 17

• alfalfa
• clover
• cereals
• equine pasture

Question 18

Fertile soils are needed for:

Answer 18

• intensive grassland

- maize

Question 19

How does the soil fertility change for grass and arable crops?

Answer 19

• Grass: SOM tends to increase

- Arable crops: SOM tends to decrease (even more without rotation of crops)

Question 20

Soil fertility comes from:

Answer 20

• Organic matter
• CEC : cation exchange capacity
• Earthworms

Question 21

Difference in land use with good and poor drainage

Answer 21

Wet lands:
- Permanent grass only
- Restricted grazing
- Restricted cutting
Dry lands:
- Maize
- Alfalfa
- Clover
- Grass

Question 22

Describe the land use system: grass land only

Answer 22

• peat soils; clay soils
• ‘extensive’ dairy farming
• grazing during day and night
• rotational grazing, or, continuous grazing

Question 23

Describe the land use system: grassland and maize

Answer 23

• sandy soils
• intensive dairy farming
• grazing during the day
• Rotational grazing; strip grazing

Question 24

Describe the land use system: High tech intensive farms, relying on maize and grassland

Answer 24

• (Dry) sandy soils
• Large farms with intensive dairy farming
• Zero grazing
• Milking robot

Question 25

Describe the land use system: Organic grassland, maize and other forage crops

Answer 25

• Production of ‘home grown’ concentrates
• Important role for legumes while no artificial fertilizers
are allowed
• Purchase of feed is limited
• Rotational grazing

Question 26

Describe the land use system: dry climates

Answer 26

– Cereals
– Lucerne/alfalfa
– Maize
– With irrigation: annual grass like Italian
Ryegrass

Question 27

Often at horse pastures yield is lower because of:

Answer 27

• Low fertiliser use

- Specific horse grass with low sugar content and low growing points

Question 28

Describe the forage management on organic farms

Answer 28

• Grazing is compulsory
• Organic feed only
• 60% of forage should be home grown or from the region
• Rations should include 60% roughage, and a maximum of
40% concentrates
• No use of artificial fertilizers
• No use of pesticides

Question 29

What is the difference between c3 and c4 plants?

Answer 29

C3: Use the calvin cycle and are found in cool/wet areas
C4: Use the Hatchslack pathway and are found in warm/dry areas