Relationship between Vegetative Ground Cover and Soil Loss - Lab Report Example

Soil Loss Practical Name Institution Introduction In any ecosystem, the vegetation ground cover can be defined as any layer of the vegetation which is below the shrub region. In most places, the common wide spreading of the ground covers are the grasses of different types. In agriculture, the term ground cover is anything lying on the surface of the soil protecting that soil from all sorts of erosion and also prevents the weeds from growing. There are several types of plants used as ground covers (Maarel 2004). These comprise: Vines, herbaceous plants, spreading types of shrubs, or any non-woody plant, large and coarse species of Moss, low-growing species of the ornamental grasses. These plants, which operate as ground covers, generally grow over a particular section and protect the ground from drought and even erosion. They also improve the aesthetic appearance of the soil. ( Andrew, 2000, p. 311) Soil loss is the phenomenon whereby the topsoil is removed at a faster rate than the rate at which the soil forming processes can replace that soil. The soil loss can be resulting from natural, animals, human activities (which include over grazed lands, over cultivated lands, clearing of forests and mechanized farming). The soil loss makes the affected soil to become infertile and might result to desertification and also devastated flooding. Soil could be lost through wind or water. Soil loss is a combination of gravitational force and the rain water which pulls the soil down the slopes. Soil loss is usually a concern for any farmer because the growth of crops depends on the health of the soil. The soil which has undergone soil loss is very unhealthy and doesn’t support the growing of crops on it. (Whisenant &Steve G. ,2008, p. 89) Method Des Lang was allowed the use some raw data resulting from an experiment on soil loss and runoff. The experiment had been carried out at Scone Research Station. The data considered are for only one year i.e.1988 even if the experiment had been done for about 8 years. The data included rainfall (mm), rainfall intensity (mm/hr), run off (mm), soil loss (kg/ha), and plot ground cover (%). The soil loss plots were 30 m long x 2.4 m wide. There were different percentages of vegetative ground cover (plot 1 - 60%, plot 2 - 20%, plot 3 - 40%, plot 4 - 60%, 2 EM311/511 Land Assessment for Sustainable Use plot 5 - 80%, plot 6 - 0%, plot 7 - 80%, plot 8 - 40%, plot 9 - 100%). There was replication of some % vegetative ground cover treatments. Vegetative ground cover was maintained by herbicides, weeding, cutting and limited burning. There was a rain gauge located at the plots as well as a pluviograph to measure rainfall intensity. Results The experiment carried out was meant to establish the relationship between the vegetation cover and the soil loss in any ecosystem. plot %cover soil loss 1 64 97 2 25 2388 3 46 521 4 65 67 5 82 0 6 8 4875 7 84 5 8 82 402 9 100 0 From the table, the soil loss is highest in plot 6. In plot 6, the land has the least percentage crop cover of 8% which translates to a 4875 Kg/ha soil being lost. It is also evident that the soil lost in plot 2, which has a 25% cover is 2888 which is second highest. Then in plot 9, which has 100% cover, there is no soil lost. These results can also be plotted on a graph of soil loss against vegetation cover as below: This shows that where there is more vegetation cover, there is less soil loss and vice versa. Thus the rate of soil loss is inversely proportional the percentage of vegetation cover in any piece of land. The results from the experiment are not very regular because there are some other losses of soil which are not very dependent on the vegetation cover. E.g. land slides. The soil loss was highest in 24th January with 3351 Kg/ha soil loss. During this period, it is when we also have the highest amount of rainfall in the region. In the period of 8th April is when we have the least rainfall (of 2mm/hr) which translates to 0 kg/ha soil loss, which means that there is no soil lost during this time. Also, from the table, it is very clear that when the rainfall is very low, the soil loss is minimal and vice versa. The cause of the utmost soil loss of 3351 Kg/ha during 24th January could be resulting from the heavy rainfalls. There are four possible categories of erosion which lead to the soil loss from these heavy rainfalls. Splash, sheet, rill and gully types of erosion. In splash erosion, the falling raindrops have impacts which eventually create smaller craters in the soil and thus ejecting soil particles. The distance travelled by these particles could even be two vertically and five feet horizontally on a leveled ground. When there is a heavy rainfall, the rate of infiltration into the soil surface is lower than the surface runoff. Thus the loosened soil particles are carried downhill. The sheet erosion is the transportation of the loose soil particles by the overland flows. Rill erosion is an increase of smaller intense flow pathways. These flow paths function as sources and delivery of sediments for the soil loss in these hill slopes. The water flows in these rills at very high pressure and increases soil loss. Gully erosion happens as a result of accumulation of run off water which then rapidly flows in channels which are very narrow, immediately or during that period of heavy rains. This ultimately results to the depletion of soil layer of a sizeable depth. (David, 2001). Discussion Human activities including grazing results to amplified soil loss. When the vegetation cover is repeatedly grazed prior to its minimum grazing heights, the roots of this vegetation starts decreasing in size. Also their ability of retaining soil anchorage. When the vegetation is grazed very closely to the ground, it leads to over exposure of this vegetation to wind and water. This makes the loose soil particle to be blown and washed away respectively. The farmers are advised to carry out some pasture management practices. They should be practicing rotational grazing techniques in their farming. Here, the farmers rotate the animals through many paddocks allowing preferable managed pastures also controlling the access to the rivers by the livestock. These paddocks help in allowing reestablishment of vegetation in these paddocks and thus reducing soil loss. (Goudie & Andrew., 2000, p. 196). By planting and maintaining vegetation in the areas which are beside the streams. This is done by fencing the livestock away from these water bodies. This vegetation helps in slowing surface run off. This allows the settling out of the nutrients and soil particles from the surface run off. This eventually reduces the bank erosion. Also by limiting the livestock from accessing some vegetation on a creek helps in slowing the water flow, thus reducing the erosion power, facilitates soil particles settling and also holds the stream banks in place. (Toy &Terrence J. 2002) In addition, these farmers are advised to shun overgrazing. Overgrazing is having a large number of animals in one locality for too long which eventually to non existent stand of vegetation covers. This effect leads to the over exposure of the loose soil to surface run off which leads to increased soil loss. The farmers are also advised to look for alternative sources of water. This can be achieved by fencing the animals away from the streams. Then providing them with piped water. This prevents them from walking all over the place while looking for water and eventually making the soil loose and prone to soil erosion. (Goudie & Andrew., 2000, p. 196). The additional information required in the experiment includes the mean daily maximum and minimum temperatures. Temperatures also increase the rate of weathering of rocks. This means that when there are high temperatures, there is a significant increase in soil loss. Also the mean daily hours of sunshine are also very vital in the experiment. Also the wind speed also increases the soil loss and thus is very important in the experiment. Also the relative humidity has a significant effect on the rate of soil loss in the experiment and should be included. Also the mean number of days is very vital in that when it is raining, we expect more soil loss through run off and air currents than when it is not raining. (Archibold 1994) The data gotten is not very much reliable as in it is from the records of only one year. Seasons, soil structures in different areas differ. They should possibly use averaged data of at least ten years for that region. They should also use data from different regions and not one locality. This allows diversity in leads to independent results which could then be averaged so as to get the final data tables. Conclusion The increased vegetation cover percentage leads to a decrease in soil loss and vice versa. Therefore, farmers are advised to look for ways so as they can increase vegetation cover on the soil of their fields. The farmers can also have rotational grazing, look for alternative sources of water, avoid overgrazing and have vegetation beside the streams. These activities make the soil particles not to be loose and exposed to erosion factors. (Andrew D. & Trimble, Stanley W., 2004, p. 259) Reference List Toy&Terrence J. (2002). Soil Erosion: Processes, Prediction, Measurement, and Control. Hoboken: John Wiley & Sons David (2001). Glacial Lake Missoula & its Humongous Floods. Alaska: Mountain Press Whisenant &Steve G. (2008). Terrestrial systems. Cambridge University: Cambridge University Press. p. 89. Goudie & Andrew. (2000). "The human impact on the soil". The Human Impact on the Natural Environment. MIT: MIT Press. pp. 196–197 Andrew (2000). "Accelerated coastal erosion". The Human Impact on the Natural Environment.MIT: MIT Press. p. 311. Andrew D. & Trimble, Stanley W. (2004). "Soil conservation and sediment budgets". Environmental Hydrology. Boca Raton: CRC Press. p. 259. Archibold. (1994). Ecology of World Vegetation. New York: Springer Publishing. Maarel. (2004). Vegetation Ecology. Oxford: Blackwell Publishers. Read More

Results The experiment carried out was meant to establish the relationship between the vegetation cover and the soil loss in any ecosystem. plot %cover soil loss 1 64 97 2 25 2388 3 46 521 4 65 67 5 82 0 6 8 4875 7 84 5 8 82 402 9 100 0 From the table, the soil loss is highest in plot 6. In plot 6, the land has the least percentage crop cover of 8% which translates to a 4875 Kg/ha soil being lost. It is also evident that the soil lost in plot 2, which has a 25% cover is 2888 which is second highest.

Then in plot 9, which has 100% cover, there is no soil lost. These results can also be plotted on a graph of soil loss against vegetation cover as below: This shows that where there is more vegetation cover, there is less soil loss and vice versa. Thus the rate of soil loss is inversely proportional the percentage of vegetation cover in any piece of land. The results from the experiment are not very regular because there are some other losses of soil which are not very dependent on the vegetation cover. E.g.

land slides. The soil loss was highest in 24th January with 3351 Kg/ha soil loss. During this period, it is when we also have the highest amount of rainfall in the region. In the period of 8th April is when we have the least rainfall (of 2mm/hr) which translates to 0 kg/ha soil loss, which means that there is no soil lost during this time. Also, from the table, it is very clear that when the rainfall is very low, the soil loss is minimal and vice versa. The cause of the utmost soil loss of 3351 Kg/ha during 24th January could be resulting from the heavy rainfalls.

There are four possible categories of erosion which lead to the soil loss from these heavy rainfalls. Splash, sheet, rill and gully types of erosion. In splash erosion, the falling raindrops have impacts which eventually create smaller craters in the soil and thus ejecting soil particles. The distance travelled by these particles could even be two vertically and five feet horizontally on a leveled ground. When there is a heavy rainfall, the rate of infiltration into the soil surface is lower than the surface runoff.

Thus the loosened soil particles are carried downhill. The sheet erosion is the transportation of the loose soil particles by the overland flows. Rill erosion is an increase of smaller intense flow pathways. These flow paths function as sources and delivery of sediments for the soil loss in these hill slopes. The water flows in these rills at very high pressure and increases soil loss. Gully erosion happens as a result of accumulation of run off water which then rapidly flows in channels which are very narrow, immediately or during that period of heavy rains.

This ultimately results to the depletion of soil layer of a sizeable depth. (David, 2001). Discussion Human activities including grazing results to amplified soil loss. When the vegetation cover is repeatedly grazed prior to its minimum grazing heights, the roots of this vegetation starts decreasing in size. Also their ability of retaining soil anchorage. When the vegetation is grazed very closely to the ground, it leads to over exposure of this vegetation to wind and water. This makes the loose soil particle to be blown and washed away respectively.

The farmers are advised to carry out some pasture management practices. They should be practicing rotational grazing techniques in their farming. Here, the farmers rotate the animals through many paddocks allowing preferable managed pastures also controlling the access to the rivers by the livestock. These paddocks help in allowing reestablishment of vegetation in these paddocks and thus reducing soil loss. (Goudie & Andrew., 2000, p. 196). By planting and maintaining vegetation in the areas which are beside the streams.

This is done by fencing the livestock away from these water bodies. This vegetation helps in slowing surface run off. This allows the settling out of the nutrients and soil particles from the surface run off. This eventually reduces the bank erosion.

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