ADVERTISEMENTS:
Here is an essay on ‘Land Degradation’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Land Degradation’ especially written for school and college students.
Essay on Land Degradation
Essay Contents:
- Essay on the Introduction to Land Degradation
- Essay on the Definition of Land Degradation
- Essay on Global Land Degradation
- Essay on the Causes of Soil Degradation
- Essay on the Causes of Land Degradation
- Essay on the Extent and Rate of Land Degradation
- Essay on the Global Extent of Soil Degradation
- Essay on Land Degradation Processes
- Essay on Land Degradation Control
- Essay on Land Degradation and Productive
- Essay on the Desertification of Land
- Essay on the Extent of Soil Degradation by Erosion
ADVERTISEMENTS:
Essay # 1. Introduction to Land Degradation:
Land degradation is a composite term, which mainly refers to the worse change in land resources including soil, water, vegetation, rocks, air, climate, relief etc., because of any reason. The occurrence of landslide is also considered as a kind of land degradation phenomena.
The land degradation signifies, the temporary or permanent declination in the productive potential of the land. In other words, it describes the view of “aggregate diminution of the productive potential of the land, including its major uses (rain-fed, arable, irrigated, rangeland, forest etc.), its farming systems and its value as an economic resource.”
The productivity of grassland and forest resources in addition to the cropland is also taken into consideration for evaluation of land degradation. As for as its extent is concerned, it depends on various agents causing degradation. Fig. 26.1 indicates the extent of the area falling under different causing agents at global level.
ADVERTISEMENTS:
Essay # 2. Definition of
Land Degradation:
ADVERTISEMENTS:
As per definition of land degradation is concerned, there have been introduced numerous terms and definitions. However, the common terms amongst them are the soil degradation, land degradation and desertification. The term desertification refers to the land degradation in arid, semi-arid and sub-humid areas due to anthropic activities.
On this view of desertification the researchers have opinioned that it is very narrow, because severe land degradation resulting from anthropic activities can also occur in temperate humid regions and in humid tropics. Similarly, the term degradation or desertification refers to irreversible declination in the ‘biological potential’ of the land. The biological potential depends on several interacting factors; which is difficult to define them.
ADVERTISEMENTS:
Soil degradation by accelerated water and wind-induced erosion is a serious problem, and found from several decades, especially in developing countries (tropics and subtropics). Erosion is a natural geomorphic process occurring continuously over the earth’s surface. Accelerated soil erosion has adverse economic and environmental impacts.
Economic effects are due to on-site and off-site reductions in income and other losses with adverse impact on crop/animal production. As per regional food production statistics for 1995 with and without soil erosion of the world, there is total loss in food production of about 31 M Mg in Africa; 190M Mg in Asia and 18 M Mg in tropical America.
Essay # 3. Global Land Degradation:
Fig. 26.1 illustrates the view of global land and soil degradations. Amongst various sources of land degradation the highest share is of desertification which is about 2.6 billions ha, followed by about 2.0 billion ha by soil degradation and 0.5 billion ha from deforestation. The shares of soil degradation at global level under different sources (water & wind erosion and physical and chemical deterioration) are shown in Table 26.1.
Similarly, the degree of variations (slight, moderate, severe and extreme) in soil degradation is also shown in Table 26.2, which reveals that amongst soil erosion sources the water erosion is major source of soil degradation amounting 56%. While wind erosion involves 28%. The soil degradations because of physical and chemical deteriorations are in the range of 12 and 4%, respectively. As for as variations in degree of soil degradation is concerned, it is 38% under slight to extreme 0.5%.
Essay # 4. Causes of Soil Degradation
:
It is mainly because of following causes:
ADVERTISEMENTS:
i. Soil Erosion by Water:
Under this reason the land degradation is caused due to continuous and long-term removal of soil mass and nutrients from the land by the action of water. Under water erosion the processes may be the sheet erosion in which a more or less uniform removal of thin layer of topsoil gets happen during storm event; rill erosion in which small channels are formed in the field when sheet erosion is not checked; and the gully erosion which accompanies the formation of bigger channels similar to incised rivers in the area. The gully erosion (gully formation) ultimately causes soil degradation.
ii. Soil Erosion by Wind:
This type of soil erosion accomplishes the removal of soil particles by wind action. Usually this is the kind of sheet erosion, in which soil is removed in thin layers, mainly. This source of land degradation is very prominent in the area having very fine to medium size sand particles; normally in deserts areas. In India this type of occurrence is very common in Rajasthan.
The soil erosion leads to reduce the soil productivity in following way:
a. Reduction in soil organic matter, resulting into declination in soil biological activities.
b. Development of bad effects on physical properties of the soil (structure, aeration, water-holding capacity etc.) due to reduced organic matter.
c. Development of nutrients deficiencies or increase in toxic levels in the soil.
d. Creation of toxic substances due to incorrect application of fertilizers in the field.
iii. Soil Fertility Declination:
The declination in soil fertility causes soil degradation because of development of bad effects on physical, biological and chemical properties of the soil.
iv. Water Logging:
This type of soil degradation is caused due to rise in groundwater table close to the soil surface, because of inadequate drainage system in the area or poor irrigation management practices. In water logging situation the soil gets completely saturate with water, as result there is development of oxygen deficiency for plant growth.
v. Increase in Salts:
Development of this problem could be due to salinization. The salinization increases the salt level in the soil water solution or sodification, i.e., increase of sodium cations (Na+) on the soil particles. The soil salinization often takes place in conjunction with poor irrigation management. The soil sodification tends to occur naturally. The areas prone to high water table fluctuation have the problem of soil sodification.
vi. Sedimentation:
The problem of sedimentation takes place through water flooding or wind blowing. Under sedimentation the fertile soil gets covered by less fertile sediments; and leading to make the soil unfit for cultivation.
vii. Lowering of Water Table:
This problem mainly arises when withdrawal of ground water exceeds the amount of water recharged in the aquifer. An area with very deep water table is also considered unfit for cultivation. The area with prolonge deep water table is treated as degraded soil.
viii. Loss of Vegetative Cover:
The vegetations are important in many ways. They protect the soil from erosion by wind and water; and also provide organic materials to maintain the nutrients level, essential for healthy plant growth. Plant roots maintain soil structure and facilitate water infiltration. A poor vegetative cover in the land is considered an important cause of land degradation.
ix. Increased Stoniness and Rock Cover:
Development of this type of problem is usually associated to the extreme level of soil erosion causing exposure of stones and rock.
A degraded soil is more likely to get further degradation as compared to the similar soil. The organic matter affects the level of soil erodibility. In normal case the level of soil organic matter judges the soil erodibility. In soil if the level of organic matter falls below 2% then soil is more prone to erosion, because soil aggregates become very weak and individual particles are more likely to get dislodge. Also, few environmental factors cause very significant risk to land degradation than the others.
Steep slope, high intensity rainfall etc., influence the likelihood of occurrence of soil degradation. The management practices also cause significant effect on susceptibility of a landscape to degradation. For example – an extensive and poorly managed land use system is more likely to get degrade than the intensive and intricately managed fields. The phenomena of serious and prolonge soil erosion cause land degradation, provided that the rate of soil formation is at very slow rate than the rate of soil erosion.
In general, in moist and warm weather conditions the formation of a few centimeter of soil may take thousands of years; while in cold and dry climates it can take more than the above. Also, when soil is without vegetative cover then rate of soil loss through erosion can go up to 300 times faster. In this way, the soil erosion is the most widely recognized and most common source of land degradation; and also is a major cause of declining the soil productivity.
Essay # 5. Causes of Land Degradation:
The most commonly recognized causes of land degradation are given as under:
1. Overgrazing of rangeland.
2. Over-cultivation of cropland.
3. Water logging and salinization of irrigated land.
4. Deforestation.
5. Pollution and industrial causes.
6. Inappropriate land management practices.
These causes result the conversion of suitable and high potential lands into unsuitable and low potential lands; failure of using soil conservation measures in the areas of high degradation risks, and removal of crop residues resulting into ‘soil mining’, i.e., extraction of nutrients at greater rate than the supply rate. Many badlands such as extremely bare, de-vegetated and eroded slopes are badly degraded. However, such lands can be rehabilitated by using improved technologies.
The effect of land degrading process differs depending on the inherent characteristics of land such as soil type, slope, vegetation and climate. An activity at a given place may be degrading, while same at another place may not be degrading, because of variations in soil characteristics, topography, climatic conditions etc. Similarly, a rainfall of a given erosivity can cause the soil erosion at varying rates in the soils of different inherent characteristics.
Essay # 6. Extent and Rate of Land Degradation
:
The extent of degraded lands in dry areas of the world is reported as 3.6 billion ha or 70% of the total 5.2 billion ha of the total land falling under dry regions (Table 26.3.). And the global extent of land degradation is reported about 1.9 billion ha, as shown in Table 26.4. The change in extent of land-degraded area is mainly due to variations in status of vegetations. The estimates presented in Table 26.3 also includes the status of vegetative cover of rangeland. As an example the vegetation degradation in Australia is presented in Table 26.5.
Essay # 7. Global Extent of Soil Degradation
:
The total land area subject to human-induced soil degradation is estimated to the tune of 2billion ha, shown in Table 26.6. Of this, the land area affected by soil degradation due to erosion is about 1100 Mha by water erosion and 550 Mha by wind erosion. South Asia is one of the regions in the world, where soil erosion by water and wind is a severe problem (Table 26.6). Fig. 26.1 also presents the global scenario of land degradation.
Essay # 8.
Land Degradation Processes:
The principal processes of land degradation are given as under:
1. Erosion by water and wind
2. Chemical degradation –
i. Acidification
ii. Salinization
iii. Leaching etc.
3. Physical degradation –
i. Crusting
ii. Compaction
iii. Hard-setting etc.
The above listed processes of land degradation may act singly or in combination, depending on the situation. Few lands or landscape units may be affected by more than one process of water or wind erosion, salinization and crusting or compaction. An example of combination of land degradation process and area affected under them is outlined in Table 26.7.
Essay # 9. Land Degradation Control:
Various measures for control of land degradation are explained as under:
Control of Water Erosion:
i. Agronomical Measures:
These measures are the first line of action for soil erosion/loss control. The agronomical measures control the soil erosion/loss by creating soil cover. Which can be done by using mulch, growing crops and artificial stabilizers. These covers intercept the raindrops and reduce the overland flow/runoff. Apart from above the cropping practices such as contour cropping, strip cropping, cropping pattern, crop rotation, fertilization etc., are also means of agronomical measures to control the soil erosion.
ii. Mechanical Measures:
Under this category of soil erosion/loss measures, the bunding and terracing are the main. These measures are used, only when agronomical measures are not effective to control the soil loss. However, they involve limitations regarding involvement of heavy cost, design and construction.
iii. Tillage Practice:
These practices are performed for creating surface roughness to reduce the flow velocity of rainwater over the soil surface. This causes soaking of large amount of rainwater into the soil; and thus reducing the volume of rainwater, their flow velocity and ultimately the soil scouring or soil erosion. The conservation tillage, strip cropping and safe disposal of rainwater through grassed waterways are the main measures considered under this head of practice.
The control measures for physical degradation are listed as under:
i. Using the farm machineries of lesser weight.
ii. Reducing the number of passes of implements during tillage operations.
iii. Keeping off the soil when it is in wet condition.
iv. Reducing the soil compaction by deep ploughing, occasionally.
v. Reducing soil crusting by light cultivation, adding Gypsum (Ca SO4) and mulching.
Essay # 10. Land Degradation and
Productive:
There is very close relation between land degradation and productivity. As the degree of land degradation gets decrease the level of productivity also gets increase, accordingly. The degree of land degradation is divided into low, moderate and high categories based on the land properties rather their impact on productivity. The International Board for Soil Research and Management (IBSRAM) presented the relation between cumulative soil loss and runoff in relation to crop yield shown in Table 26.8.
The table value indicates that the data of China shows that despite significant differences in cumulative soil loss and runoff, there is no difference in corn yield. Similar inference is also found in Thailand. In addition, the erosion (and other degradative processes) effects on crop yield or biomass potential depend on changes in land quality with respect to specific parameters.
Essay # 11. Desertification
of Land:
It is a form of land degradation occurring particularly, but not exclusively in semi-arid regions. Table 26.9. Indicates the areas of few Asian countries vulnerable to desertification. The semi-arid to weakly arid areas of Africa are particularly vulnerable, as they have fragile soils. About 33% of the global land (42 million km2) is subject to desertification. Many of the countries cannot afford the losses in agricultural periodicity due to desertification.
The Mediterranean countries of North Africa are very highly prone to desertification. In Sahel, there are several pockets of very high-risk areas. The West African countries with their dense populations have a major problem of land degradation. The reason is that, they have high propensity along the desert margins and occupy about 5% of the landmass. Cumulatively, desertification affects about 550 million Africans. Although, good soil resources are there, but their productivity is seriously undermined by the land degradation and desertification.
The matrix of risk assessment about human induced desertification is presented in Table 26.10. Also, the risk classes of African lands is presented in Table 26.11.
Essay # 12. Extent of Soil Degradation by Erosion:
As per report presented in Table 26.12 the total area affected by soil erosion in Asian countries is 81.74 Mha under water erosion and 59 Mha under wind erosion. In India the area suffering from water erosion is maximum to the tune of 32.8 Mha, followed by 26.4 Mha in Iran; 11.2 Mha in Afghanistan; 7.2 Mha in Pakistan; 1.6 Mha in Nepal; 1.5 Mha in Bangladesh and 1.0 Mha in Sri Lanka.
In case of wind erosion the maximum affected area is in Iran, i.e.35.4Mha, followed by 10.8 Mha in India, 10.7 Mha in Pakistan and 2.1 Mha in Afghanistan. The maximum affected area under soil erosion is in India about 328.8 Mha, 165.3 Mha in Iran, 79.6 Mha in Pakistan, 65.3 Mha in Afghanistan, 14.7 in Nepal, 14.4 in Bangladesh, 6.6 Mha in Sri Lanka and 4.7 Mha in Bhutan.
