2.Plant Nutrition Flashcards
What is the standard way to reduce pH?
- Sulphur - converted to Sulphuric acid by micro organisms
- Aluminum sulphate (fertiliser)
- Pine needles used as a mulch
What is the standard way to raise pH?
- Add lime (Chalk) in autumn
- Spent mushroom compost
- Calcium carbonate
What are the advantages of liming?
- Raises pH and can make other nutrients available
- Provides calcium
- Encourages worm and bacteria population
- Discourages some diseases such as clubroot in brassicas
- Makes clay soils workable by flocculation (improved aeration, drainage)
Name 2 plants that prefer acid soils (calcifuges).
- Rhododendron
- Camelia japonica
Name 2 plants for neutral soils.
- Iris spp
- Aster spp
Name 2 plants for alkaline soils (calcicoles).
- Clematis alpina
- Viburnum tinus
What is meant by fertiliser?
- Concentrated form of nutrients applied to the plant environment to increase and sustain plant growth
- Can be organic or inorganic
What is meant by soluble fertiliser?
Give an example.
- Dissolves immediately with water
- Ammonium sulphate
What is meant by slow-release fertiliser?
Give an example.
- Doesn’t dissolve immediately with water but provides nutrients in soluble form over a long period of time
- Degrade slowly, usually under the influence of soil micro-organisms to release their nutrients
- Dependant on soil temperature
Hoof & horn / Bone meal
What is meant by a straight fertiliser?
Give an example.
- Supply one major nutrient
- Usually used to provide different nutrients at different times of the year, or to correct particular nutrient deficiencies
- Usually inorganic
Ammonium nitrate (N)
What is meant by a compound fertiliser?
Give an example.
- They may be organic or inorganic, or contain both
- Supply two or more of the major nutrients
Growmore (NPK)
What is meant by a controlled-release fertiliser?
Give an example.
- Granules of inorganic fertilisers coated with a porous material, so release at right time for plant
- Water enters the granule and the fertilisers leach out into the surrounding soil
- The warmer the soil, the faster the leaching; this corresponds to plant growth which is faster in warm weather
- By varying the thickness of the coating granules can be designed to feed plants for different periods of time.
Osmocote
What is meant by base dressing and when would you apply it?
- Fertiliser incorporated into soil at final prep stage
- Dug in before sowing/planting
- Spread over surface and forked/raked into top 10cm
- E.g Triplesuperphosphate applied to seed bed
What is meant by top dressing and when would you apply it?
- Added to surface of soil of established plants
- Lightly forked into soil surface
- Usually compound fertiliser
- E.g lawn feed applied in autumn
What is meant by liquid feed and when would you apply it?
- Fertilisers dissolved in water
- Applied to the soil or growing media, directed to the roots of plants
- Mostly used on pot plants, outdoor containers
- E.g. Tomorite may be applied to tomato plants growing in pots in a greenhouse
What is meant by foliar feed and when would you apply it?
- Application of fertiliser in a diluted form to the foliage of the plant
- Fast acting
- Used to correct nutrient deficiencies
- Wasteful as a lower percentage of the nutrients supplied actually enter the plant
- E.g. a foliar feed of Epsom salts may be applied to correct magnesium deficiency in the foliage of apple trees
Name organic fertilisers.
- Fish, blood and bone (N,P,K)
- Poultry manure (N)
- Bonemeal (P, N)
- Comfrey tea (K)
Name inorganic fertilisers.
- Growmore (N,P,K)
- Ammonium sulphate (N)
- Potassium sulphate (K)
- Triple super-phosphate (P, Ca)
Why is pH 6.5 the most suitable pH for a wide range of plants in the UK?
- Availability of nutrients is at its highest
- Soil organism activity is at its optimum
What are immobile nutrients?
Name 4 examples
Nutrients which do not easily move within the plant
- calcium (Ca)
- iron (Fe)
- sulphur (S)
- boron (B)
What are mobile nutrients?
Name 4 examples.
The nutrients which move around within the plant
- nitrogen (N) in the form of nitrate
- phosphorus (P) in the form of phosphate
- potassium (K)
- magnesium (Mg)
State whether each of these materials are acid, neutral or alkaline?
Peat, Coir, Green manure, Composted bracken, Wood ash, Ammonium sulphate
Peat – Acidic
Coir – Neutral
Green manure – Acid
Composted bracken – Neutral
Wood ash – Alkaline
Ammonium sulphate – Acid
Benefits and limitations of organic fertilisers?
Benefits:
- Generally safe to use - no risk of toxic build up
- Sustainable (animal and plant material)
- Provide a steady supply of nutrients of over a long period
- They do not react so readily with other fertilisers
- Encourage soil micro organisms
Limitations:
- Often slow acting and need to be applied well in advance of planting
- The amounts of nutrients may vary considerably
- Breakdown by micro organisms is dependent on temperature
What are the benefits and limitations of inorganic fertilisers?
Benefits:
- Precise nutrient content
- As they are more concentrated only small amounts are needed
- Water soluble and not temp dependent
- Nutrients are available to plant immediately and do not need micro organisms to break them down first
Limitations:
- Many react with other fertilisers so care is required if combining them.
- Can be detrimental to soil organisms
- Environmental concerns such as run-off into watercourses
- High environmental impact - fossil fuels
What is meant by the term pH?
- Expresses the amount of acidity or alkalinity in the soil
- Between 1 - 14
- 7 is Neutral
- Below 7 = Acidic
- Above 7 = Alkaline
- PH of 6.5 is ideal for most plants (6-7)
Why do plants need nitrogen?
Symptoms of Excess/Deficiency
- Large amounts needed
- Leaf/ vegetative green growth
- The dark green pigment in plants (i.e. chlorophyll)
- Most easily leached from the soil
Excess
- Excessive Soft, lush leafy growth
- Vulnerable to pests/disease
- Easily damaged by cold
Deficiency
- Slow growth
- Yellowing of leaves ( Chlorosis - due to lack of chlorophyll)
- Bluing of older leaves
- More noticeable in older leaves
Why do plants need phosphorus?
Symptoms of Excess/Deficiency
- Plays a vital role in energy transfer - Produces ATP
- Needed in meristematic tissue for shoot and root growth
- Essential to seed formation and germination,often found in large quantities in seed
Excess
- Reduces plants ability to take up micro-nutrients
- Yellowing of leaves/Poor health
Deficiency
- Weak/poor root growth - Poor plant development
- Stunted new growth
- Blue/purple leaf and stem colouring
Why do plants need potassium?
Symptoms of Excess/Deficiency
- Needed for flower/fruit formation
- Increases plant hardiness
- Osmotic regulator – critical in reducing water loss from leaf stomata and increasing uptake of water via the roots
Excess
- Leads to nitrogen deficiency
- Yellowing of leaves
- Slow growth
Deficiency
- Poor flowering or fruiting, yields
- Brown/ scorched areas on leaf tips/edge
Why do plants need calcium?
Symptoms of Deficiency
- Integral part of plant cell walls – holds cell wall together after cell division
- Promotes cell division (meristems) especially in root tips
Deficiency
- Weakened cell walls
- Stunted growth
- Inward curling, pale young leaves
Why do plants need magnesium?
Symptoms of Deficiency
- Key component of chlorophyll, plays a critical role in photosynthesis
- For healthy leaves
Deficiency
- Yellowing of leaves between the veins
Why do plants need Iron
Symptoms of Deficiency
- Involved with chlorophyll production
Deficiency
- Yellowing of leaves between the veins– younger ones first
- Failure to flower and fruit
List 3 Major and 3 Minor nutrients
Major
- Nitrogen (N)
- Phosphorus/ Phosphate (P)
- Potassium/ Potash (K)
Minor
- Calcium (Ca)
- Magnesium (Mg)
- Iron (Fe)
List key effect of soil PH on organisms within the soil
- Worms and beneficial bacteria do not like acidic soils - raising PH is more beneficial to these organisms
- Clubroot is more common in acidic soils
- Common scab of potatoes occurs in alkaline soils
- Overtime soils become more acidic due to rain, the activity of soil organisms and added fertilisers
