1. Define the term macronutrient and list four examples of macronutrients that plants
require. Macronutrients are nutrients which a plant requires in large quantities. Four
examples are; carbon, oxygen, nitrogen and phosphorus.
2. Define the term micronutrient and list four examples of micronutrients that plants
require. Micronutrients are essential for plant growth but are required in much smaller
quantities. Four examples are; iron, copper, manganese and zinc.
3. Why do most farmers add inorganic fertilizer to the soil? They add inorganic fertilizer
to the soil to increase plant yields by supplying plants with the necessary nutrients that
are in short supply.
4. What do the three numbers on a bag fertilizer mean? The first number refers to the
amount of nitrogen. The second number refers to the amount of phosphorus. The third
number refers to the amount of potassium.
5. Describe the symptoms of:
(a) nitrogen deficiency in plants – reduced plant growth and a pale green or yellow color.
(b) phosphorous deficiency in plants – reduced plant growth, delayed maturity, and small
fruit.
(c) potassium deficiency in plants – reduced plant growth and a yellowing and/or burning
of leaf edges.
6. What are the advantages of using inorganic fertilizers? The benefits are that they
produce high yields, are easy to apply and are relatively inexpensive.
7. Identify four problems (drawbacks) associated with the use of inorganic fertilizers.
(a) The energy requirements to produce fertilizers. If projected fertilizer use becomes a
reality the potassium reserves will only last 107 years and the phosphate deposits only 88
years.
(b) The greenhouse effect due to more nitrous oxide emissions. Fossil fuels for the
production of ammonia emit carbon dioxide into the atmosphere.
(c) Leaching of the nutrients not absorbed by the plants can contaminate ground water
and surface water.
(d) Health hazards of some fertilizers containing nitrogen.
8. Identify four things that we (humans) can do to reduce the impact of inorganic
fertilizer use on the environment.
(a) Reduce leaching by applying fertilizers at a rate which is equal to plant uptake.
(b) Growing some sort of vegetation on the field to plough it into the ground to increase
the amount of organic matter in the soil.
(c) Create new strains of crops that fix their own nitrogen.
(d) Rotating fields with different crops reducing the amount of nutrients depleted
because different plants require varying amounts of nutrients.