R2102 3.1 – 3.3 Plant Nutrition COPY Flashcards
Role of iron and signs of deficiency?
Involved with chlorophyll production
Symptoms:
Yellowing of leaves – younger ones first
Failure to flower and fruit
What is the standard way to reduce pH?
Sulphur, aluminum sulphate or sulphuric acid are fastest
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 3 plants that prefer acid soils (calcifuges).
- Rhododendron*
- Camelia japonica*
- Pieris japonica*
Name 3 plants for neutral soils.
- Malus*
- Cucumis*
- Daucus*
Name 3 plants for alkaline soils (calcicoles).
- Clematis montana*
- Agapanthus africanus*
- Fagus sylvatica*
Which nutrient is most likely leached form soil and therefore needed to be replaced?
Nitrogen
What is meant by soluble fertiliser?
Give an example.
Dissolves immediately with water
Ammonium sulphate
Potassium chloride
Ammonium nitrate
Superphosphate
Triple superphosphate
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
- Usually organic and include hoof & horn and 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 (33-35% N)
Superphosphate (21% P)
What is meant by a compound fertiliser?
Give an example.
- They may be organic or inorganic, or contain both
- Supply two or more nutrients of N, P and K (N:P:K), e.g. 20-10-10
- Potassium nitrate (46%K, 14%N) supplied both K and N
- Growmore 7-7-7 supplies 7%N, 7%P, 7%K.
- K: potassium sulphate (50%K)
What is meant by a controlled-release fertiliser?
Give an example.
- Granules of inorganic fertilisers coated with a porous material, such as sulphur or synthetic resin, 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
Dug in before sowing/planting
What is meant by top dressing and when would you apply it?
Added to surface of soil
When nutrients are needed after plants are established e.g lawns in autumn
What is meant by liquid feed and when would you apply it?
- Fertilisers dissolved and watered onto soils
- Applied to the soil or growing media, directed to the roots of plants
- A liquid feed of a compound fertiliser (e.g. Tomorite) may be applied to tomato plants growing in pots in a greenhouse, hanging baskets and pot plants
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
- Generally restricted to application of trace elements
- Works relatively quickly and can be used to correct nutrient deficiencies
- It is a wasteful method, 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
Comparison of organic matter to fertilisers
OM bulky, F concentrated
OM low-nutrient content, F high
OM imprecise control, F precise control
OM slow effect, F quick effect except slow release
OM effective over long period, F effect may be quickly lost
OM improves soil structure, F no impact on soil structure
OM will contain pests and diseases, F no pests and diseases
Describe the construction of a compost heap.
(i) Accessibility of the site: positioned in a sheltered area away from wind, orientated away from heat e.g. south and west.
ii) Mixture of soft green (25–50%) and brown (woody) material
(iii) Avoid perennial weeds/seeds /diseased/cooked material
(iv) Material to be shredded to increase surface area
(v) Suitable materials include vegetable peelings, shredded prunings, herbaceous material etc.
vi) Constructed on bare soil, wooden sides, cover to keep excessive rain off, compost heap to be minimum size of 1m³, material to be layered inside the compost heap.
vii) Ensure that the compost heap does not dry out, water when required, turn the compost heap regularly by turning the outer edges into the centre to ensure that all the material can become hot
Name 2 organic fertilisers.
Fish, blood and bone
Bonemeal
Name 2 inorganic fertilisers.
Growmore:
Growmore has a ratio of 7:7:7 for these materials, but is actually 7% nitrogen, 3.1% phosphorus and 5.8% potassium, or 7:3.1:5.8. Therefore it is a high-nitrogen feed, rather than the ‘balanced’ fertiliser commonly assumed.
Ammonium sulphate:
For alkaline soils. The ammonium ion is released and forms a small amount of acid, lowering the pH balance of the soil, while contributing essential nitrogen for plant growth
What is meant by the term pH?
Expresses the amount of acidity or alkalinity in the soil in terms of hydrogen ions concentration. The more hydrogen ions the more acidic.