Lecture 2: Land use and yields Flashcards
(29 cards)
What is the main purpose of growing grass and forages?
- Feed: Milk and meat production
- Living space: Grazing and resting
What are sub purposes of growing grass and forages?
- 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
What is the fourth stage of grass growth called?
- Dying off = senescence
Describe stage 1 of grass growth
- 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
Describe stage 2 of grass growth
- Elongation
- Internode elongation, important for timing of
grazing/mowing, so as not to destroy the
growing tip - Grass tips contain fatty acids: linoleic acid
Describe stage 3 of grass growth
- 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
How are flowerheads described?
- 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
What is photosynthesis?
- 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
Environmental influences on grass growth?
Temperature: optimal temperature depends on the crop
- Light intensity: light saturation occurs at some point
- Carbon dioxide: the most commonly limitating factor
What is plant respiration?
- 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)
What are the key elements of photosynthesis?
- Produces sugars from light energy
- Stores energy
- Occurs only in cells with chloroplasts
- Oxygen is produced
- Water is used
- Carbondioxide is used
- Requires light
What are the key elements of respiration?
• 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 lightWhat is gross photosynthesis?
- Total amount of CO2 fixed by the plant
What is respiration (short definition)
- Amount of CO2 lost from metabolic activity
What is net photosynthesis?
- net amount of primary production after the costs of plant respiration are included
• Net photosynthesis = Gross photosynthesis -Respiration
What is the growing season of grass like?
• 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
Less fertile and dry soils are suitable for:
- alfalfa
- clover
- cereals
- equine pasture
Fertile soils are needed for:
- intensive grassland
- maize
How does the soil fertility change for grass and arable crops?
- Grass: SOM tends to increase
- Arable crops: SOM tends to decrease (even more without rotation of crops)
Soil fertility comes from:
- Organic matter
- CEC : cation exchange capacity
- Earthworms
Difference in land use with good and poor drainage
Wet lands: - Permanent grass only - Restricted grazing - Restricted cutting Dry lands: - Maize - Alfalfa - Clover - Grass
Describe the land use system: grass land only
- peat soils; clay soils
- ‘extensive’ dairy farming
- grazing during day and night
- rotational grazing, or, continuous grazing
Describe the land use system: grassland and maize
- sandy soils
- intensive dairy farming
- grazing during the day
- Rotational grazing; strip grazing
Describe the land use system: High tech intensive farms, relying on maize and grassland
- (Dry) sandy soils
- Large farms with intensive dairy farming
- Zero grazing
- Milking robot
