Decaying remains of plants & animals - Manure and bone meal
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Examples of artificial fertilisers (non organic)
Nitrogen, phosphorus and potassium always present
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Why are fertilisers needed?
Mineral ions are absorbed by crops which are then harvested from its point of origin and the faeces of the consumer are not returned to the same land.
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What gives the greatest productivity?
A combination of artificial and natural fertilisers but minerals need to be added in appropriate amounts
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How do fertilisers increase productivity?
Where nitrates are available, the plant will develop earlier, grow taller and have greater leaf area and so photosynthesis will increase.
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Name the 3 environmental effects from using nitrogen fertilisers
Reduced species diversity, leaching, eutrophication
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Why does reduced species diversity occur from using fertilisers?
Nitrogen rich soils favour the growth of grasses, nettles and other species. These out-compete other species which then die.
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How does leaching affect the environment?
Leached nitrates drain into streams and fresh water lakes and pollute the water. High nitrate levels in drinking water can prevent efficient oxygen transport in babies.
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Describe Eutrophication
Nitrate conc increases in river --> algrae grow at surface (algal bloom) --> prevents light penetrating lower depths --> dead plants and algae at bottom --> increase in demand for O2 for saprobiotics --> O2 limiting factor for aerobic organisms
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