What are the 2 main reasons why agricultural land needs fertilisers?
If same crop is grown in a field, all the plants remove the same nutrients from the soil as they have the same requirements. Because crops are harvested, they don't decompose, so they don't put nutrients back into the soil.
1 of 18
What does intensive farming mean?
Lots of crops grown in a small area, or lots of animals in a confined space. Involves inputs like fertilisers and food supplements. It gives a higher yield per hectare.
2 of 18
What is a requirement of fertilisers?
They need to be water-soluble.
3 of 18
What is the most widely used fertiliser?
Ammonium nitrate, which contains NH4+ and NO3-.
4 of 18
Why is ammonium nitrate good for improving crop yield?
Good source of nitrogen, which is used by plants to make amino acids to make proteins which are used for growth. Therefore there's a increased crop yield and profit.
5 of 18
Why are fertilisers used sparingly?
They are expensive, so farmers will only use them if they give enough increase in yield to compensate for the cost of buying and applying them.
6 of 18
Describe the effect that adding fertiliser has on crop yield.
Increasing fertiliser will increase crop yield up to a point. Soil must have been deficient in fertiliser to begin with, so adding it increases plant uptake & growth. Adding above a certain amount wastes money-something else must be limiting growth.
7 of 18
What is the economic optimum?
This is the least money the farmer has to spend on fertilisers for the greatest crop yield.
8 of 18
Describe the eutrophication process.
Excess fertiliser washed into rivers when it rains. Causes algae to grow in water. Blocks sunlight of other plants which die off. They're decomposed by aerobic bacteria. Bacteria use up oxygen, water becomes stagnant and other species die.
9 of 18
What are the advantages of using manure instead of fertilisers?
Can be used on organic farms. Improves soil structure to help root growth. Slower release of nutrients, so less chance of eutrophication.
10 of 18
What are the disadvantages of using manure instead of fertilisers?
Don't know exact nutrient status, so don't know how much to apply. Bulky and time-consuming to transport and apply to the soil.
11 of 18
What do pesticides include?
Insecticides, fungicides and herbicides.
12 of 18
What is a broad-spectrum pesticide?
Kills lots of types of pest, so it could harm useful organisms.
13 of 18
How are pests becoming resistant to pesticides?
Chance mutations- some pests aren't killed by pesticide. Pesticide kills susceptible pests, but others survive. They live long enough to breed & pass on resistance alleles to next generation. Resistant pests in the population increase over time.
14 of 18
What is a problem with pesticides?
They may linger on the food we buy and eat.
15 of 18
What is a problem for organic farmers?
They are limited as to which pesticides they're allowed to use.
16 of 18
What are antibiotics?
Chemicals that kill bacteria. They are naturally made by other micro-organisms, but most are now made in labs.
17 of 18
Why are antibiotics sometimes used by farmers for their animals?
When animals are kept in intensive conditions, they're often crowded together. Diseases can spread quickly and easily. Using antibiotics keeps down the overall number of bacteria and reduces the chance of disease occurring.
18 of 18
Other cards in this set
Card 2
Front
What does intensive farming mean?
Back
Lots of crops grown in a small area, or lots of animals in a confined space. Involves inputs like fertilisers and food supplements. It gives a higher yield per hectare.
Card 3
Front
What is a requirement of fertilisers?
Back
Card 4
Front
What is the most widely used fertiliser?
Back
Card 5
Front
Why is ammonium nitrate good for improving crop yield?
Comments
No comments have yet been made