Everything Life Sciences Grade 10

Mineral Source Main Functions Deficiency Disease

Macro-nutrients

Calcium (Ca) inorganic fertilisers;

Ca ions in the soil

part of the plant cell wall;

transport and rention of

other elements

chlorosis

Magnesium (Mg) inorganic fertilisers;

Mg ions in the soil

component of

chlorophyll (pigment for

photosynthesis); activates

many enzymes required

for growth

chlorosis (the low

production or loss of

chlorophyll in plant

leaves)

Nitrogen (N) inorganic fertilisers in

the form of nitrates;

symbiotic

nitrogen-fixing

bacteria in roots

component of

chlorophyll; nucleic

acids and proteins; seed

and fruit production

stunted growth;

smaller leaves

Phosphorus (P) inorganic fertilisers in

the form of

phosphates; low

amounts in the soil

photosynthetic process;

part of nucleic acids and

cell membranes; root

growth

stunted growth,

blue/green leaves

Potassium inorganic fertilisers; K

ions in the soil

needed for protein

synthesis,

photosynthesis, enzyme

activation, opening and

closing of stomata;

chlorosis; curling leaf

tips; brown

scorching, poor fruit

quality

Sulfur (S) inorganic fertilisers protein synthesis; root

growth; chlorophyll

formation; promotes

activity of enzymes

chlorosis

Micro-nutrients

Iron (Fe) inorganic fertilisers;

Fe ions in the soil

component of the

enzyme that makes

chlorophyll

chlorosis

Zinc (Zn) inorganic fertilisers;

Zn ions in the soil

part of growth-regulating

enzyme systems

poor leaf growth

Sodium (Na) inorganic fertilisers;

Na ions in the soil

maintains salt and water

balance

reduced growth

Iodine (I) inorganic fertilisers; I

ions in the soil

needed for energy

release during respiration

poor growth

Table 2.3: Nutrients required for plant growth.

Use of fertilisers

When crops are regularly grown and harvested on the same piece of land, the soil becomes

depleted of one or more nutrients. Fertilisers are natural or non-natural mixtures of chemical

substances that are used to return depleted nutrients to the soil, improve the nutrient content

of the soil and promote plant growth. Inorganic nutrients (such as nitrates and phosphates)

are added to the soil in the form of inorganic fertilisers.

Effect of fertilisers on the environment

Using large amounts of fertilisers can be harmful to the environment. Fertilisers wash off into

rivers where they are poisonous to plant and animal life. The accumulation of fertilisers in

rivers can lead to a process known aseutrophication. This process occurs when excessive

nutrients (nitrates and phosphates) from the land (typically from fertilisers) run off into rivers

28 2.3. Inorganic compounds