agricultural energetics

Question 1

what is the difference between intensive and extensive agriculture

Answer 1

1) extensive involves spreading inputs over a large area producing a lower yield per total area but an increased efficiency as the total output of energy is far greater than the input
2) intensive is where large inputs of energy are available over a small area of lad increasing productivity per unit of land but has decreased efficiency fort the output is similar to input

Question 2

what is meant by the term law of diminishing returns

Answer 2

each extra unit of input results in an increase in yield but the size of each successive increase gets smaller as output of energy decreases

Question 3

what is an energy subsidies

Answer 3

• any input that aids productivity but requires the use of energy for example
  manufacture of nitrate fertilisers
  pumping of irrigation water
  fuel for machinery

Question 4

what is an energy ratio

Answer 4

the measure of efficiency by comparing energy inputs and outputs and then expressing this as a number of units of food energy produced per unit of energy input
the higher the ratio the more efficient the system

Question 5

what are food conversion ratios

Answer 5

a measure of the mass of food needed to produce a given mass of livestock growth, the lower the ratio the better the conversion of food into animal biomass

Question 6

what is autotrophic nutrition and what is the advantage of this mode of nutrition

Answer 6

• organisms that are able to synthesize their own complex organic molecules, such as glucose to amino acids, through photosynthesis (photoautotrophs) or chemosynthesis (chemoautotrophs)
• this mode of nutrition is beneficial as they do not rely on other organisms for their energy supplies

Question 7

what is heterotopic nutrition

Answer 7

1) organisms that obtain their complex organic molecules through other organisms

Question 8

where is most the energy lost in autographs before being converted into another trophic level

Answer 8

1) metabolic processes

2) heat

Question 9

why do food chains never exceed much more than four trophic levels

Answer 9

energy is lost at each trophic level via different metabolic processes such as respiration or movement etc, but also has heat, therefore less energy is transferred to the next trophic level

Question 10

why do food chains never exceed much more than four trophic levels

Answer 10

energy is lost at each trophic level via different metabolic processes such as respiration or movement etc, but also has heat, therefore less energy is transferred to the next trophic level