Discuss the Advantages and Disadvantages of the use of Fertilisers and Pesticides in Agriculture

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Discuss the Advantages and Disadvantages of the use of Fertilisers and Pesticides in Agriculture

        Agriculture today dominates the majority of all land uses. As a result it has a fundamental role in maintaining the countryside and protecting the environment. The development of the use of fertilisers and pesticides has dramatically increased the efficiency of food production and has in fact more than quadrupled food production in the last century. They also have reduced the cost and increased the variety of foods available. However, there are serious consequences to the uses of many of these pesticides and fertilisers and they have resulted in various environmental problems.

Fertilisers:

        In a natural ecosystem plants eventually die and decay. When the plant dies, it decomposes and bacteria and other soil microorganisms break down organic molecules and release the nutrients back into the soil. However, in a farm, the plants (i.e. crops) are harvested and the nutrients are removed with them. If a high yield is to be maintained for a number of years the nutrients must be replaced. Therefore in order to maintain productivity in agriculture farmers need to use fertilisers containing these nutrients.

There are two types of fertilisers used by farmers in agriculture: inorganic fertilisers and organic fertilisers. They both have advantages and disadvantages within themselves. Inorganic fertilisers are concentrated sources of macronutrients and can therefore be applied in smaller amounts. As a result saving on transport costs and on damage done by heavy farm machinery being driven over the soil. They are also clean and lack the smell of organic fertilisers; and are easier to handle and apply. Organic fertilisers add organic matter to the soil. This can reduce the soil erosion and improve water-holding properties. Also as it is often used as a waste product on mixed farms, applying farm manure to a plant crop is a useful way of disposing of this waste.

The most commonly used fertilisers are the soluble inorganic (chemical) fertilisers. They are products of natural rocks; and contain cations and anions in a concentrated form. These cations and anions are the same as those that occur naturally in fertile soil. There are usually three primary nutrients within these chemical fertilisers (although are contained in organic fertilisers too); all of which have certain properties playing an important part for increasing a higher yield in agriculture. These are Nitrogen, Phosphorus and Potassium (NPK).

  • Nitrogen is fundamental for leaf growth, which is where photosynthesis mainly takes place; therefore vital in increasing crop yields. Nitrogen also contains a number of proteins, so therefore also affecting the quality of the crop.
  • Phosphorus is important for cell division so therefore is needed by parts of the plant that are growing rapidly. It is found in many of the organic substances the plant produces, i.e. nucleic acids, ATP.
  • Potassium is used for both respiration and photosynthesis.

These are contained in a mixture of chemical compounds such as ammonium nitrate, calcium phosphate and potassium sulphate. By adding these fertilisers, they should replace or replenish the nutrients in the soil and thus increase the yield of crops. Inorganic fertilisers are very affective but also have undesirable effects on both the environment and for the crops themselves:

  1. Various commonly applied fertilisers may reduce the percentage of germination of maize, wheat, sorghum, millets and other cereals, groundnut, other legumes and the seeds of a number of other crops. In some instances, the reduction in germination of the young seedling is produced through osmosis (for example, in urea), or through a toxic effect (by ammonium salts and notably, in decreasing order, by anhydrous ammonia, ammonium nitrate, and ammonium sulphate).
  2. Chemical fertilisers can also have an affect on the rate of growth of young roots and stems. This is linked with the reason above for reduction of germination.
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  1. They can result in ‘scorching of young growth’. Ammonium salts; mainly ammonium sulphate and ammonium nitrate induces a ‘scorch’ or ‘burn’. Careless application of ammonium sulphate to the roots of young coffee, tea, cocoa and other plants may produce scorching of the foliage…and result in death of part or all of the plant.
  2. The continuous application of ammonium sulphate (used commonly in the tropics and subtropics) may greatly reduce the soil pH (increasing soil acidity). This may result in the necessity of liming, which is almost impossible on a large scale. An increase in acidity of ...

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