Tut 1 Basics

1. In what form do plants absorb Nitrogen, Phosphorus and Potassium?
Nitrogen: in the form of Nitrates
Phosphorus: in the form of Phosphates
Potassium: in the form of Potassium salts

2. What do fertilizers typically consist of?
Nitrates, Phosphates and Potassium salts

3. How are ferlilizers sold?
They are sold in bags, marked with the ratio of Nitrates, Phosphates and Potassium salts.

4. What is meant by the N:P:K fertilizer ratio?
These are three smallest whole numbers such as 1:2:4 whcih tells us the relative amounts of nitrogen, phosphorous and potassium in the bag itself.

5. Why is the N:P:K fertilizer ratio important?
This ratio provides imnportant information to the farmer so that he can choose the correct ferlilizer for his crops.

6. What is the purpose of each of the N:P:K?
N (nitrogen): promotes leaf growth and forms proteins and chlorophyll
(good for lettuce farmers)
P (phosphorus): contributes to root, flower and fruit development
(good for fruit farmers, carrots etc)
K (potassium): contributes to stem and root growth and the synthesis of proteins
(good for mielie farmers)

Example, an N:P:K ratio of 1:2:5 would be the choice for a mielie farmer since it contains more K.

7. What is meant by the term eutrophication?
Eutrophication is what happens when a farmer uses too much fertiliser.
Assume a farmer uses too much fertiliser.
When it rains:
• The excess fertilizer flows into rivers.
• This promotes algae growth (algae bloom).
• When this extra algae decomposes, this process consumes the dissolved oxygen from the water.
• Other water organisms such as fish, then also die as a result of oxygen deprivation.
• Water that has a very low concentration of oxygen is said to be hypoxic

8. What are some of the ecomomic consequences of eutrophication?
• Fisherman would have no fish to catch, hence no income
• Holiday resorts with water recreational areas, that are nearby the farm, would not have many guests due to poor and dangerous water conditions (unattractive) - job losses
• Water for drinking, washing and cooking is spoilt, creating a health risk.

9. How can eutrophication be avoided?
• The farmer must calculate and measure out correct amounts of fertiliser to use.
• Use fertiliser sparingly
• The farmer must use advanced modern, computerised equipment to ensure correct amounts are actually delivered to the ground
• Avoid irrigation just after applying fertiliser
• Do not use aeroplanes to drop fertlisers since this can spread too far
• Do not apply fertilser when it is very windy
• Ensure that water from crop fields do not run into rivers and dams.
• Redirect water from crop fields into specially made reservoirs, away from rivers and dams.

10. Why must over-fertilisation be avoided?
• This can cause damage to crops and soil, resulting in small or no harvest, which means less income.
• Excessive fertiliser may seeps into groundwater, and contaminate drinking water.
• Excessive fertiliser causes run-off into rivers and dams and causes eutrophication, that may result in less income, starvation, poor quality of drinking water and fewer recreation areas.
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