SOIL EROSION

– loss of soil

– process of soil erosion where soil is detached from its place and transferred to another place. it is soil erosion.

2 Processes Are Important

Detachment of soil particles- in field soil is there and particles are aggregated & get detached
These detached particles are transported- they are transported to another place where they are deposited or lost anywhere.

# These two processes are carried by 2 agents/forces i.e. water & wind
-Water & wind are responsible for detachment and transported of soil particles & they are known as erosion agents. 

Natural erosion-

Under natural conditions due to rain or wind there will be erosion of soil. In every situation there is natural erosion by wind & water. This natural erosion causes loss of soil but this loss of soil is compensated by soil formation process.

In natural conditions there are 2 processes-

Soil formation process by rock weathering- physical, chemical or biological weathering.

Factors (wind & water- natural agents)  we cannot change rainfall pattern or wind speed to reduce erosion, we can’t control it for an area but the practices that is being done in that area- cultivation practices, farm practices it increases the rate of erosion.

Factors that influence the rate of erosion-

1) RAINFALL
Water erosion occurs in diff stages
  1. Stage-1 Sheet ErosionWhen there is rainfall, flowing water carries soil with it and water is muddy. Uniform removal of top soil, thin layer is removed and fertile soil is lost. The top fertile layer is removed from the field & fertility & productivity is reduced. Generally it is ignored because water is flowing and is not recognized.
  2. Stage-2 Rill Erosion- Water is moving making a uniform channel along the slope. Small shallow depth channels can be seen & soil moves along with the water through these shallow depth channels.
  3. Stage-3 Gully Erosion- Advancement of rill erosion. The channels become wide, broad & deep & water flowing volume is more as compared to rill erosion. Rills become wide and deep and carry more water and soil and cause more soil erosion.
  4. Stage-4 Revine- advance stage of gully is formation of ravines. The channels become very broad & deep and it starts out as the site of a small stream or river. The water wears a deep grove into the earth, which affects water as it drains from other locations, speeding up erosion process.
  5. Landslides- landslides occurs mainly in hilly areas. Rain gets into rocks & cause them to become unstable. When unstable rock & soil get wet they get heavier. Once, a landslide occur rate of erosion by water & wind speeds up.
2) WIND SPEED
Wind erosion occurs in diff ways-

2.1 Saltation- (Jumping action)- when wind flows, it makes pressure/hit soil particles, particles move into air and again come back to surface-jumping action.

about 30-60 cm above from surface.

medium size particles about 0.1mm-0.5mm

50-75% soil is eroded by saltation

2.2 Surface creeping-(rolling action) particles roll on surface, they do not come into the air-particles are heavy, they can’t come into air. Wind makes pressure on it & they start rolling on surface. Rolling is not for much distance.

particle size- >0.5mm

5-20% soil is eroded

2.3 Suspension-(floating action) very small particles come into air & start floating in air. Particles are very small so they travel long distances.

particle size- <0.1mm

3-4% soil is eroded

3) SOIL ERODIBILITY
– If erodibility is high, soil is more prone to erosion

Erosivity– erosion causing power of agent (power of wind & water to cause erosion)

– Erosivity more, erosion will be more.

3.1 Aggregation- In soil particles are present in aggregates. If aggregation is more then there is more water stable aggregate, then detachment will be less, erodibility will be less & less chances of soil erosion

– if aggregation is good in soil, there is less chance of erosion.

3.2 Slope (Steepness)- if slope is more, water runoff is more, it will detach and transport the soil more.

3.3 Slope Length- if slope length is more, erosion will be more.

3.4 Physical characteristics in relation to aggregation- the soil having more aggregation, detachment will be less & transportation will be less.

Sandy (Coarse textured) Clay (Fine textured)
In sandy soil aggregation is poor, detachment is easy but transportation is low because sand particles are heavy In clay aggregation is more & detachment is less but transportation is easy & light particles are transported easily.
 SandClay
DetachmentEasyDifficult
TransportDifficultEasy
InfilterationEasy b/c macropores are thereLow b/c micropores, sealing of pores
Runofflessmore

Chemical Properties:

4) VEGETATION
  • Falling raindrop are intercepted by the vegetation, splash is less, sealing of pores is less, & transportation of soil is less.
  • Wind will hit soil very less with less force & detachment will be less.
  • Leaf drip or canopy drip- rain drops are intercepted by the leaves of trees and decrease velocity of water falling on soil.
  • Stem flow- water is intercepted by plant & flow into the soil by stem, velocity is decreased.
  • Some water is in canopy & directly hit the soil, it is called through fall.
5) FARMING

When land is worked through crops or other agricultural processes, it reduces the overall structure of the soil, reducing the levels of organic matter, making it more susceptible to the effects of rain and water. Tilling often breaks up and softens the structure of the soil, can be a major contributor to erosion

6) UNSHELTERED DISTANCE

Unsheltered distance with lack of windbreaks such as trees, shrubs, crop residue, etc. make way for the wind to put soil particles into motion for greater distances, thereby increasing soil erosion. Knolls and hilltops are usually exposed without any vegetation cover and suffer the most.

EFFECTS OF SOIL EROSION

  1.   Loss of Topsoil- This is the biggest effect of soil erosion. Because topsoil is so fertile, if it is removed, this can cause serious harm to farmer’s crops or the ability to effectively work their land.
  2. Soil Compaction- When the soil under the topsoil becomes compacted and stiff, it reduces the ability for water to infiltrate these deeper levels, keeping runoff at greater levels, which increases the risk of more serious erosion.
  3.   Reduced Organic and Fertile Matter- Removing topsoil that is heavy with organic matter will reduce the ability for the land to regenerate new flora or crops.When new crops or plants can’t be placed successfully in the area, this perpetuates a cycle of reduced levels of organic nutrients.
  4.      Poor Drainage- Sometimes too much compaction with sand can lead to an effective crust that seals in the surface layer, making it even harder for water to pass through to deeper layers. In some ways, this can help erosion because of the densely packed soil, but if it perpetuates greater levels of runoff from rainwater or flooding, it can negatively impact the crucial topsoil.
  5. Issues With Plant Reproduction- When soil is eroded in active cropland, wind, in particular, makes lighter soil properties such as new seeds and seedlings to be buried or destroyed. This, in turn, impacts future crop production.
  6. Soil Acidity Levels-When the structure of the soil becomes compromised, and organic matter is greatly reduced, there is a higher chance of increased soil acidity, which will significantly impact the ability for plants and crops to grow.
  7. Long Term Erosion- Unfortunately, if an area is prone to erosion or has a history of it, it becomes even harder to protect it in the future. The process has already reduced the soil structure and organic matter of the area, meaning that it will be harder to recover in the long run.
  8. Water Pollution- A major problem with runoff from soils – particularly those used for agricultural processes – is that there is a greater likelihood that sediment and contaminationlike the use of fertilizer or pesticide. This can have significant damage on fish and water quality.

MANAGEMENT FACTORS TO REDUCE SOIL EROSION

1. Careful Tilling- Because tilling activity breaks up the structure of the soil, doing less tilling with fewer passes will preserve more of the crucial topsoil.

2. Crop Rotation- Plenty of crop rotation is crucial for keeping land happy and healthy. This allows organic matter to build up, making future plantings more fertile.

3. Increased Structure For Plants- Introducing terraces or other means of stabilizing plant life or even the soil around them can help reduce the chance that the soil loosens and erodes. Boosting areas that are prone to erosion with sturdy plant life can be a great way to stave off future effects.

4. Water Control- For those areas where soil erosion is predominantly caused by water – whether natural or man-made – specialized chutes and runoff pipes can help to direct these water sources away from the susceptible areas, helping stave off excess erosion. Having these filters in particular areas rather than leading to natural bodies of water is a focus to reduce pollution.

5. Soil Conservation- Soil conservation can be defined as “the combination of the appropriate land use and management practices that promotes the productive and sustainable use of soils and, in the process, minimizes soil erosion and other forms of land degradation.”

Various measures for soil conservation are primarily meant for the prevention of soil loss or reduced fertility caused by acidification, over usage, salinization or other chemical soil contamination.

Different techniques for improved soil conservation involve cover crops, crop rotation, planted windbreaks, and conservation tillage and affect both fertility and erosion.

6. Increased Knowledge- A major factor for preventing soil erosion is educating more and more people who work with the land on why it is a concern, and what they can do to help reduce it.

This means outreach to farmers in susceptible areas for ways that they can help protect crops from inclement weather or ways that they can help make sure their soil remains compact without restricting their plant growing activities.

SOIL CONSERVATION

Soil provides the nutrients essential for plant growth, animal life, and millions of microorganisms. Soil conservation focuses on keeping soils healthy through a combination of practices and techniques. Soil conservation helps to ensure that soil is fertile and productive, and protect it from erosion, degradation & depletion.

The major objective of conservation of the soil is maintaining its biodiversity of inhabiting eco-communities that contribute to its fertility in their own ways. They add organic matter, split perished organisms to release nutrients, improve water infiltration, and aeration.

 

BENEFITS OF SOIL CONSERVTION

  1. Boosts earth quality and productivity- Maintaining the natural environment for earth-dwelling organisms increases fertility and reduces the necessity of chemical fertilizing, thus boosting yields and saving costs at the same time.
  2. Mitigates erosion- Soil conservation methods reduce erosion and depletion, help agriculturalists to avoid the expansion of new lands when territories become infertile.
  3. Promotes water infiltration and increases its storage- The soil conservation technique of minimum tillage vs. conventional plowing affects soil moisture by reducing cracking and evaporation as well as rising the infiltration rate.
  4. Gives food and shelter for wildlife– Land with growing vegetation is a living environment for animals; it is not only the source for nourishment but their home as well.

SOIL CONSERVATION PRACTICES

  1. Conservation tillage- The conservation tillage aims at addressing wind and water erosion by covering the earth with vegetation (either crops or their residues) and limiting the number of tilling operations. No-till farming involves planting seeds into the residue of the previous crop, with no tillage between harvests. No till leaves 60 to 70 percent of a field covered with crop residue.
  2. Contour Farming- If ploughing is done at right angles to the hill slope, following natural contours of the hill, the ridges and furrows break the flow of water down the hill
    • This enables plants to absorb more moisture and reduce erosion
  3. Strip cropping– In this case, farmers combine high-growing crops with low-growing ones for the sake of wind protection, like when corn grows in strips with forage crops. The strip cropping practice works even better when high-growing crops are intensified in the sides where winds blow most frequently. An extra benefit is the organic matter material from the low crops.
  4. Windbreaks- this soil conservation practice is used to reduce the power of winds and its disruptive effect on soil. These are trees or bushes to shelter crops from snow and winds planted in several rows.
  5. Windbreak vegetation also provides a living environment for wildlife and eliminates soil abrasion on crops due to strong wind blows.
  6. Crop Rotation- When same crop is grown year after year, it takes away certain same nutrients away from soil, making it infertile.
    • Hence, different crops have to be grown, as different crops take up different nutrients throughout the year
    • Growing leguminous plants helps in fixing nitrogen to the soil
  7. Cover Crops- This soil conservation technique is another way to avoid bare soils and additionally benefit from planting cover crops – secondary species – in-between growing cash crops for different reasons like to:
    • produce forage and grazing material for cattle;
    • provide green manure;
    • assist in weed control;
    • retain moisture;
    • ensure a natural environment for microorganisms and minor animals;
    • balance nitrogen concentration
  8. Step Away From Synthetic Fertilizers And Pesticides- Chemicals application to control weed and pest infestations are harmful to the environment and undesired in soil conservation.
  9. Integrated Pest Management-. It is important to eliminate synthetic herbicides replacing them with organic ones or establishing biological enemies of pests whenever possible, rotating crop species to minimize increasing pest populations in the same field for years, and using alternative techniques in complex.

MULCHING

Types of mulches-
  1. Organic mulches- plant residues (straw, hay, haulms, leaf), manures (compost, farm yard manure, peat) and wood products (saw dust).
  2. Synthetic mulches- paper, polythene, wax coated papers, aluminum foils and asphalt sprays emulsions.
    1. Soil mulch or dust mulch- if the soil surface is loosened, it acts as mulch to reduce evaporation. It is called soil mulch or dust mulch. Intercultivation creates soil mulch in growing crops. Its usefulness is doubtful in alfisols but helps in closing deep cracks in vertisols.
    2. Stubble mulch- crop residues like wheat straw or cotton stalks etc. are left on the soil surface as a stubble mulch.
    3. Stone mulch- mainly useful in rainfed agriculture system of the arid region. Stones/pebbles are used for covering soil.
    4. Plastic mulch- plastic materials like polythene, polyvinyl chloride are used as mulching materials
    5. Vertical mulching- to prolong the beneficial effect of subsoiling, vertical mulching method is used. The slots are filled with organic matter and keeping them open and functional for a longer period. In black soils, to improve infiltration and storage of rainwater vertical mulches are formed. It consists of digging narrow trenches across the slope at intervals and placing the straw or crop residues in these trenches.