2102 - Fertilisers

Question 1

What is meant by ‘Fertilisers’

Answer 1

A Fertiliser is a concentrated source of plant nutrients in a known and stated amount. Fertilisers are added to the soil to increase and sustain plant growth.

They are used to replace lost nutrients in the soil, depleted through leaching or harvesting crops.

• components of fertiliser must be know
• quantity of each nutrient must be stated

Question 2

Bulky Organic Matter vs Fertilisers

Answer 2

BOM

• High Volume
• Low Nutrient
• unknown nutrient content
• improves structure, fertility and organisms

Fertiliser

• Low volume
• High Nutrient
• Stated Nutrient Content
• Improves fertility

Question 3

Soluble Fertilisers

Answer 3

Fertilisers dissolved in water to be applied as a liquid feed.
Watered onto soil/plant roots to give an instant boost.

Mainly for greenhouse crops, pot plants and bedding (fast growing annuals). Fast acting.

Eg. Maxicrop, Tomorite, Liquid Lawn Food

Question 4

Foliar Feed

Answer 4

A dilute solution of fertiliser applied directly to the leaves. Used to quickly correct nutrient deficiencies, or provide an additional feed for example hanging baskets.

Eg. Sequestered Iron (Califuge plants, Camelia japonica)

Question 5

Base Dressing

Answer 5

Incorporated into the soil before planting or sowing. Can be used as a pre-sowing fertiliser for grass seed.

Eg. Growmore

Question 6

Top Dressing

Answer 6

Applying fertiliser on the soil surface around plants.

Eg. Potassium sulphate
Used as an annual application in Spring to established Roses.

Question 7

Straight Fertiliser

Answer 7

Containing high concentration of one macronutrient. Used to provide different nutrients at different times of the year, to correct nutrient deficiency.

• ammonium nitrate
• potassium sulphate
• hoof and horn
• dried blood
• bone meal
• superphosphate
• sulphate of ammonia

Question 8

Compound fertiliser

Answer 8

Contain more than one macronutrient. Can be a balanced formula or may supply more of one nutrient than others.

• growmore
• fish, blood and bone

Question 9

Organic Fertiliser

Answer 9

Derived from plant or animal sources
Straight:
- dried blood 13:0:0 (fast)
- horn and hoof 12:0:0 (slow)

Compound:

• bone meal 4:18:0 (slow)
• fish, blood and bone 6:6:6 (fast/slow)

Tend to be by-products, so more environmentally sound way of using waste-material.
Usually slow release, as the nutrients are released into the soil by soil organisms.
May be ineffective in winter, as soil organism are inactive in colder weather.

May attract vermin, Foxes, Rats etc

Always wear gloves, and wash hands after use. PPE.

Question 10

Inorganic Fertiliser

Answer 10

Derived from rock sources or Chemical manufacture.
Straight:
- Ammonium sulphate 21:0:0 (fast)
- Epsom salts 16% Mg (fast)
- Superphosphate 0:18:0 (fast)
- Urea 46:0:0 (fast)

Compound:

• growmore 6:6:6, 10:10:10 (fast)
• osmocote (CRF, various formulas)

Mined or produced chemically, not very environmentally sound.
Over application can cause more harm to the plant, resulting in scorching and plasmolysis or the roots.
Leaching can cause damage to aquatic life and waterways.

High levels of a particular nutrient may interfere with the uptake of another.
Always apply with correct PPE mask if needed, gloves and wash-hands after use.
Avoid direct contact with plant leaves and stems.

Question 11

Slow Release

Answer 11

usually derived from organic sources.
Soil organisms break down the compounds to release nutrients.

• horn and hoof 12:0:0

Question 12

Controlled Release - CRF

Answer 12

each granule is covered with a semi-permeable, bio degradable resin.
Release content in a predictable manner according to soil moisture and temperature.
Differing lengths of time can be achieved with thickness of resin.

3-4 months for quick maturing crops
5-6 months for seasonal hanging baskets
8-9 months for herbaceous borders and plant pots
18 months for trees

Suitable mainly for Containers or Lawns, not particularly garden borders.

• Osmocote (CRF, differing formulas)

Question 13

Always consider…

Answer 13

Health and Safety implications
Timings of applications
(too much nitrogen with risk of frost?)
Variability of the material

Question 14

Organic vs Inorganic

Answer 14

organic:
Benefits Plant and soil organisms
Slow Release, less chance of over application
Provide trace elements
Relatively expensive compared with....

inorganic
benefits only plants
most quick release, can over apply quite easily
usually no trace elements
relatively inexpensive compared with...

Question 15

Nitrogen Fertilisers - leafy

Answer 15

Ammonium Sulphate 21:0:0
soluble, good boost to young plants early in season, can lower soil pH.

Ammonium nitrate 35:0:0
soluble, liquid feed for glasshouse crops

Urea 46:0:0
Very high Nitrogen content. Very quick release, liquid or foliar feed (lawns)

Question 16

Phosphorous Fertilisers - roots and shoots

Answer 16

Superphosphate 0:18:0
widely used available in powder or granular form.
often used as base dressing when planting and in potting composts

Triple Superphosphate 0:48:0
very high phosphorous content

Question 17

Potassium Fertilisers - Fruits and Flowers

Answer 17

Potassium chloride
widely used but can lead to excess chlorine in the soil, not good for confined spaces (glasshouse)

Potassium sulphate
used widely for glasshouse crops, excess can cause magnesium deficiency

Potassium nitrate
soluble and used in liquid feeds.

Question 18

Magnesium Fertilisers

Answer 18

Magnesium sulphate

Epsom salts

Question 19

Disadvantages of Fertilisers cont…

Answer 19

Can lead to Toxic effects, plasmolysis and scorching.

Do not improve soil structure, reduce water evaporation compared to well rotted organic matter.

Over-use can lead to environmental issues. Damaging watercourses, lakes and rivers.

Increasing availability of one nutrient will increase the need for other nutrients possibly leading to a depletion.
High levels may also interfere with the uptake of others.