Agricultural energetics Flashcards
how is the intensity of agriculture measured?
by how much inputs are fed into the system and the yield that is then produced
what two ways can as much be produced from agriculture?
extensive farming
intensive farming
what is extensive farming?
maximise yields by spreading the inputs over a large are
what is an example of extensive farming?
typical of hill sheep where the soil isn’t good enough to have a lot of sheep in a small area
what is intensive farming?
where large inputs are placed onto relatively small pieces of land
include fertiliser, labour and energy
what are the advantages of intensive farming?
yield usually high
what are the limitations of intensive farming?
calculated yields per unit of inputs may not be very high
so productive but not always efficient
what links productivity and efficiency? (agriculture)
explained by the law of diminishing returns
what is the law of diminishing returns?
initially extra unit input (fertiliser or manpower) results in increased yield
size of each yield increase gets smaller over time
As there is only such much that can be added (nutrients, light) to a crop or animal before it cant grow any more
what does the law of diminishing returns mean for intensive farming?
is a limit to how efficient it is and productivity may improve if some areas that are intensively farmed as not farmed intensively
total global inputs should be spread over more areas
what is an energy subsidy?
any input that aids productivity but requires the use of energy
what are examples of agriculture energy subsidies?
manufacture nitrate fertilisers
manufacture pesticides
pumping irrigation water
fuel for machinery (Ploughing spraying harvesting)
energy to manufacture machinery and equipment
heat for drying harvested grain
processing food for consumers
transport food to consumers
what ways do farms subsidise their energy from fossil fuels?
will use fossil fuels for heating, lighting instead of natural sunlight and normal outside temperatures
CO2 will be pumped into crop farms as a part of photosynthesis
in the USA how much of the fossil fuel is spent on agriculture?
17%
what aspects of agriculture is especially fossil fuel intensive and why?
to power heavy farming machinery
process foods
refrigerate foods during transportation
production of packaging material
manufacture and transport chemical inputs (fertiliser)
why are energy ratios used? (Agriculture)
measure of efficiency by comparing energy inputs and outputs and then expressing them as the number of units of food energy produced per unit of energy input
What will the yield of area with higher energy ratio values?
higher yield per unit of energy
Is energy ratio the same as productivity per unit area?
no a system with high productivity may require high energy subsidies therefore have a low energy ratio
