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''Soil organisms are vital to the substantial fertility of the ecosystem'' Discuss this with reference to a) Breakdown of organic material b) Replenish the nutrient available pool.

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Introduction

''Soil organisms are vital to the substantial fertility of the ecosystem'' Discuss this with reference to a) Breakdown of organic material b) Replenish the nutrient available pool Soil organisms are a key biological component in both the breakdown of organic material and the replenishment of the nutrient available pool. They are also vital to the sustainability of fertility of any ecosystem. Over 80% of organic matter fixed by the process of photosynthesis enters the soil. Due to soil biota, the nutrients within the organic matter are released, contributing to the nutrient available pool. Without the presence and activity of soil organisms, ecosystems will constitute of litter within a matter of years. Nutrients are also essential to the growth and fertility of plants. Nitrogen in the atmospheric state is inert, and has no role in the biological cycle. However, with the presence of certain bacteria's (e.g. nitrifying bacteria), nitrates are formed which is a fundamental aspect of life. The breakdown of matter, which contributes to the substantial fertility of ecosystems, is a result of many kinds of terrestrial decomposers. ...read more.

Middle

These nitrifying bacteria oxidise ammonia to nitrite ions, which in turn can be used as an energy substrate by species of a second genus of soil bacteria, nitrobacteria. These bacteria further oxidise nitrite ions to nitrates, a form of nitrogen, which is once again available for the uptake by plant roots, providing another route within the nitrogen cycle. This process is summarised by the equations 2NH3 + 3O2->2HNO2 +2H2O + Energy (nitrifying bacteria e.g. Nitrosomonas) 2HNO2 -> 2HNO3 +Energy (nitrifying bacteria e.g. Nitrobacter) Nitrogen pays an important role in biology because of its incorporation in the structures of purines and pyramidines, which leads to the formation of DNA. The DNA molecule is the bases of reproduction, which constitutes partly of nitrogen. Nitrogen is also required in the process of respiration because of its formation in ATP molecules. Without the presence of nitrogen fixing bacteria, it will be inevitable to see the death and extinction of plants, which would severely damage the ecosystem. Rhizobium, which is present in root nodules of leguminous plants, is an example of mutual relationship. ...read more.

Conclusion

This will lead to the conversion of fertile land into barren landscape. However, the sustainability of carbon can only be achieved through soil organisms like earthworms. Earthworms are an important detritivore in the formation and sustainability of soil. Not only is dead organic matter utilised, but also the structure within the soil caused by the earthworm is of benefit to other functions within the soil. The tunnelling of the worm allows the presence of oxygen, which can then be used in the process of nitrification of ammonia into nitrites or nitrites into nitrates. This then provides plants the sources for growth and reproduction. It is quite obvious that soil organism is vital to the sustainability of any ecosystem. Without the recycling of vital nutrients such as carbon and nitrogen, the key components of life cannot be available to any organisms. This will lead to the reduction of biodiversity. It can even lead to the extinction of organisms in the higher trophic levels as energy and resources are not sufficient in the lower levels. Therefore, humans owe these soil organisms the diversity and substantial fertility of species within ecosystems. Aliya Rahman Sunday 6 October 2002 ...read more.

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