Use of natural & artificial fertilisers

Question 1

How is energy transfer increased in the food chain?

Answer 1

-agricultural ecosystems increase the efficiency of energy transfer along human food chains through the use of fertilisers which leads to increased productivity

Question 2

Why do we need fertilisers?

Answer 2

• all plants need mineral ions, especially nitrates, from the soil
• specific areas of land are used repeatedly to achieve maximum yield from the crops and animals grown on them the growing population means there are large demands on the soil because mineral ions are continually taken up by the crops being grown on it
• in natural ecosystems the minerals that are removed from the soil by plants are returned when the plant is decomposed by microorganisms on its death
• in agricultural systems the crop is harvested and then transported from its point of origin for consumption
• the urine, faeces and dead remains of the consumer are rarely returned to the same are of land
• under these conditions the concentrations of the mineral ions in agricultural land will fall
• it is therefore necessary to replenish these mineral ions because otherwise their reduced concentrations will become the main limiting factor to plant growth
• productivity will consequently be reduced
• to offset this loss of mineral ions, fertilisers need to be added to the soil

Question 3

What are they types of fertilisers?

Answer 3

• natural organic fertilisers

- artificial inorganic fertilisers

Question 4

What does research tell us about fertilisers?

Answer 4

• research suggests that a combination of natural and artificial fertilisers gives the greatest long-term increase in productivity
• however it is important that minerals are added in appropriate quantities as there is a point at which further increases in the quantity of fertiliser no longer results in increased productivity

Question 5

How do fertilisers help increase productivity?

Answer 5

• plants require minerals for their growth
• let us look at nitrogen as an example
• nitrogen is an essential component of amino acids, ATP and nucleotides in DNA
• both are needed for plant growth
• where nitrate ions are readily available, plants are likely to develop earlier, grow taller and have a greater leaf area
• this increases the rate of photosynthesis and improved crop productivity
• there can be no doubt that nitrogen-containing fertilisers have been of considerable benefit in providing us with cheaper food
• it is estimated that the use of fertilisers has increased agricultural food production in the UL by around 100% since 1995

Question 6

What are natural organic fertilisers?

Answer 6

-natural fertilisers consist of the dead and decaying remains of plants and animals as well as animal wastes such as manure, slurry and bone meal

Question 7

What are artificial Inorganic fertilisers?

Answer 7

• artificial fertilisers are mined from rocks and deposits and then converted into different forms and blended together to give the appropriate balance of minerals for a particular crop
• compounds containing the three elements, nitrogen, phosphorous and potassium are almost always present

Question 8

What are the different forms of nitrogen-containing fertiliser?

Answer 8

• nitrogen containing fertiliser can be applied to crops in a number of different forms
• these include ammonium salts, animal manure, the ground-up bones of animals (bone meal), and urea (a waste product found in the urine of mammals)
• an investigation was carried out in which the same crop was grown on six separate plots of land each of the same area
• no nitrogen-containing fertiliser was added to the first plot
• to each of the remaining five plots a different form of nitrogen-containing fertiliser was added at the rate of 140 kg total nitrogen per hectare