13.5 - Environmental Issues Concerning Use Of Nitrogen-containing Fertilisers

• reduced species diversity • leaching • eutrophication

• nitrogen-rich soils (can be achieved with fertilisers) favour growth of grasses, nettles and other rapidly growing species • these out compete other species which die as a result of

• when nutrients are removed from the soil, rainwater dissolves any soluble nutrients (e.g. nitrate ions) • and carries them deep into the soil, eventually beyond plant roots reach • other leached nitrate ions may find their ways into water ways

Caused by leaching of fertilisers into water courses

• artificial • inorganic ions in chemical fertilisers are relatively soluble, therefore excess minerals that aren’t used immediately are more likely to leak into waterways • Whereas in natural fertilisers, • the nitrogen and phosphorus are still contained in organic molecules that need to be decomposed by microorganisms before they can be absorbed by plants. • This means that their release into the soil for uptake by plants is more controlled and leaching is less likely

1) mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers 2) Large amounts of algae block light from reaching the plants below 3) Eventually the plants die because they’re unable to photosynthesise enough 4) Bacteria feed on the dead plant matter. The increased number of bacteria reduce the oxygen conc. in the water by carrying out aerobic respiration 5) Fish and other aquatic organisms die because there isn’t enough dissolved oxygen (anoxic conditions)

• measuring dissolved O2 conc. • measuring chlorophyll levels • checking if fish are alive (bioindicators) —> HOWEVER: seasonality might affect the accuracy of