13.4 Use of natural and artificial fertilisers

Question 1

Why are fertilisers needed

Answer 1

. In specific areas of land that are repeatedly used to achieve maximum yield
. Intensive food production makes large demand on soil as mineral ions are continually taken up by crops and removed to be sold and eaten (or are fed to animals that will be eaten)

So mineral ions from soil are removed, so concentration of them falls

It is necessary to replenish these or plant growth will be limited, and productivity will be reduced.

Question 2

How do agricultural land ecosystems differ to natural ones

Answer 2

In natural ones, minerals that are removed from soil are returned when plant decomposes by microorganisms.

However in agriculture crop is removed and transported away so the excretion from the consumer happens far away.

Question 3

What are natural fertilisers

Answer 3

Consist of dead or decaying plant and animal remains, as well as manure and bone meal

Question 4

What are artificial (inorganic) fertilisers

Answer 4

. Mined from rocks and deposits and then converted into different forms and blended together to give appropriate balance of minerals for a particular crop.
Eg phosphorus, nitrogen and potassium are usually present

Question 5

How do fertilisers increase productivity

Answer 5

. Plants need minerals for growth, eg nitrogen for DNA, ATP, amino acids.

These are needed for plant growth, so where nitrate ions are available plants will develop earlier and grow taller and have greater leaf area

This increases rate of photosynthesis and improves crop productivity