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Food production and conservation.
Use of fertilisers.

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  1. 1. The need for cheap and plentiful foodAs a consumer, the man is involved In the research for a wide rangeof food at minimum cost. This research put the farmers underpressure to cut costs and supply cheap food in order to stay inbusiness. So, they used intensive method of food production with itsconsequent impact on the environment.There is clearly a conflict between our wish for cheap and plentifulfood and our desire to conserve the environment.The question is: how skilfully can we balance these two conflicting needs?
  2. 2. Agricultural ecosystemsAgricultural ecosystems are strongly artificially controlled by humans to prevent themFrom reaching their natural climax communities, they’re maintained in an arrested statecalled Plagioclimax.They’re made up by largely of domestic animals and plants used to produce food forhumans.Natural Ecosystem Agricultural EcosystemNo additional energy input beyond solar energy Energy from food and fossils fuels needed in addition to solar energy in order to maintain a plagioclimaxLower productivity Higher productivityMore species diversity Less species diversityMore genetic diversity between species Less genetic diversity within species that are selectively bred or genetically engineered for a narrow range of desirable characteristicsNutrients ar recycled naturally within the Natural recycling of nutrients is oftenecosystem with little addition from outside supplemented by the addition of fertilisers.Pupulations are controlled only by natural means Populations are controlled by both natural meanssuch as competition, climate, predation and and the use of other agents such as pesticidesdiseases
  3. 3. Conflict between intensive food production and conservationThe increasing of food production is made up by the improved genetic varieties of plantand animal species,Greater use of chemical fertiliser and pesticides, greater use of biotechnology, andchanges in farm practices. These change have had many ecological impacts like thediminish of the variety of habitats.Certain practices have directly removed habitats and reduced species diversity1. Removal of hedgerows and grubbing out woodland2. Creating monocultures3. Filling in ponds and draining marsh and other wetland4. Over-grazing of landBut, there are many management techniques that can be applied in order to increase speciesand habitat diversity without unduly raising food costs or lowering yields.
  4. 4. Examples of conservation techniques:-Maintain existing hedgerows at the most beneficial height and shape.-Plant hedges rather than erect fences as field boundaries.-Maintain existing ponds and where possible create new ones.-Leave wet corners of fields rather than draining them.-Plant native trees on land with a low species diversity.-Reduces the use of pesticides.-Use organic fertilisers.-Use crop rotation.-Use intercropping to control weeds-Create natural meadows.-Leave the cutting of verges and fields edges , until after flowering and when seeds have dispe
  5. 5. USE & EFFECTS on ecosystems of nitrogen-containing fertilisers
  6. 6. In natural ecosystems not all the minerals that are removed from the soil by plants are returned. When the nutrient levels of agricultural land are low, fertilisers need to be added to the soil to offset the reduction in mineral ions.CROPS FOR FOOD OR ANIMALS’S FORAGE NEED A LOT OF NUTRIENTSIN THE SOIL, ESPECIALLY NITROGEN. WHERE FOOD PRODUCTION ISINTENSIVE, IT IS USUALLY NECESSARY SUPPLYING NITROGEN TO THESOIL.THIS CAN HAVE HARMFUL ECOLOGICAL CONSEQUENCES. natural (organic) fertilisers: consist of The fertilisers are the dead and decaying remains of plants and animals as well as animal of two types wastes (manure and bone meal) artificial (inorganic) fertilisers: that are mined from rocks and converted into different forms and blended together to give the appropriate balance of minerals
  7. 7. IT IS IMPORTANT THAT NUTRIENTS ARE ADDED IN APPROPRIATE QUANTITIES. INFACT THEAPPLICATION OF FERTILISER IS SUBJECT TO THE LAW OF DIMINISHING RETURNS, BECAUSEAN OVERAPPLICATION CAN ACTUALLY REDUCE YIELD BECAUSE:  high mineral levels, especially of nitrate, lead to rapid vegetative growth. Plant grow tall and are easily flattened by wind or rain, with subsequent reduction in photosynthesis  where minerals and water are readily available, roots develop less extensively, plants may be easily uprooted and germination and early growth are slower The law of diminishing returns: after a certain level of fertilizers’s input the yield drops
  8. 8. EFFECTS OF NITROGEN FERTILISERSThere can be no doubt that nitrogen fertilisers have been a considerable benefit inproviding us with food. It’s estimated that the use of fertilisers has increased agriculturalfood production in the UK by around 100% since 1955.But the additional use of nitrogen-containing fertilisers has also had some negative effects.These include:• reduced species diversity• increased soil acidity• pollution of drinking water• eutrophications EUTROPHICATION BY FERTILISERS It’s a natural process that occurs mostly in freshwater lakes and the lower reaches of rivers; where eutrophication occurs the sequence of events is as follows: • the higher concentration of salts encourages the growth of algae & this leads to the water becoming densely populated with algae • light dont penetrate to any depth and so plants at lower levels die • the dead plants are quickly decomposed by saprobiontic bacteria; these bacteria use up oxigen for aerobic respiration & consequential creating an increased biochemical oxygen demand (BOD) • a rise in BOD means a lower oxygen content of water and thats why organisms such as fish die due to te lack of oxygen
  9. 9. ALTERNATIVES TONITROGEN-CONTAINING FERTILISERS Practices that can be used to reduce the need to use nitrogen-containing fertilisers including: • crop rotation: by growing a different crop on a particular area of land each year, soil fertility may be maintained and the risk of desease reduced; • intercropping: based on a principle similar to crop rotation, with two or more crops being grown together; • growing genetically engineered varieties of a crop: they have had a nitrogen- fixing gene introduced into them artificially
  10. 10. ADVANTAGES & DISADVANTAGES OF USING ORGANIC &INORGANIC FERTILISERS advantages disadvantages •supply all the necessary •not easily obtained Natural nutrients for growth •bulky and therefore •increase water retention of expensive to transport(organic) the soil •slow actingfertilisers •effective over a long period •difficult to handle •improve the crumb structure •may contain pathogens of the soil •mineral content low and variable •quick acting •do not improve the soil’s Artificial •easy to handle physical characteristics(inorganic) •relatively cheap •can be easily removed by •easily obtained leaching and so need to be fertilisers •do not spread desease regulary applied •mineral contain can be •run-off can cause pollution of adjusted water courses