Synthetic inorganic fertilisers
are dealt with in
Part 4b.
You can control disease and insect damage
without using GM crops by the use of herbicides and pesticides,
but there are advantages and disadvantages.
Pesticides are chemical compounds
designed to be toxic to any living thing that attacks crops and
reducing damage to crops and increase yields by utilising pest
control methods.
'Pests' include
microorganisms-pathogens including bacteria and fungi, a
variety of insects and mammals like rats.
Insecticides kill insects that
may eat or damage the crops, reducing yields.
Herbicides kill weeds that
compete with the crop for water, light and minerals in
the soil.
Fungicides kill any fungus that
damage the crop, reducing quality and yield.
The pest control is usually
sprayed onto crops to kill the 'pest', but they are
often toxic to humans and other animals that are not
considered as pests e.g. bees, ladybirds and birds of
prey are affected - anything higher in a food chain is
affected if their food supply is damaged.
The minimum 'safe level' of pesticide
is applied to minimise contamination of toxic chemicals
accumulating in the local ecosystem food chains.
Insecticides kill insects,
fungicides kill fungi, herbicides kill weeds.
All of these increase crop yields and
are extensively used for intensive farming methods, but not
without unwanted consequences.
Again, as with fertilisers, they are not to be
overused and unfortunately organisms like insects and bacteria can
undergo mutations and develop 'strains' resistant to e.g. a
particular fungicide
or insecticide product.
This is happening all the time, so new costly
products have to be developed all the time.
As well as treating plant crops with anti-pest
agents, you can vaccinate livestock against certain diseases.
Antibiotics can be given to animals to protect against bacterial
pathogens - but this means antibiotics have entered the food chain,
so we may consume them - not good for our immune system?
Plant growth hormones are applied to
crops to encourage growth and increase crop yields.
You can also control when crops ripen and
harvesting - as far as I know, these methods are not controversial.
See
Hormone control of plant growth and uses of plant hormones
gcse biology notes
Growth hormones are also used in cattle
rearing as well as feeding the animals supplementary high protein
foods.
Animals may be deliberately confined in
huge cattle sheds to minimise movement, so less energy is wasted
and more used for growth - so hormones, protein food and
confinement all increase the energy transfer to the cattle.
BUT, the ethics of these methods is being
questioned and there are biological consequences too.
The spread of a disease is rapid because
of the close confinement of the animals.
Cattle have been bread to produce greater
yields of beef meat or greater volumes of milk, but such animals
and not as genetically healthy as their predecessors e.g.
lameness in milk cows.
Is it fair to not allow the animals to
move naturally freely beyond their 'cages'?
The unethical nature of some animal
transportation and slaughtering.
When cattle are given hormones to
increase milk and meat yields - these hormones
are entering the food chain to reach us and out into the environment
via faeces!
