Over-cultivation is an action that has brought about a lot of devastating effects on the globe. Just as the terminology suggests, it is the practice of excessive farming on a piece of land to the point of degradation of the soil as well as the land itself. Farmlands are desired for their rich base in nutrients, especially for the soil, in order to provide the necessary nutrient to the crops. Rich soil means a priced land.
Continued cultivation of the crops on the same soil without additional input reduces the marginal productivity of the soil due to exhaustion of nutrients; thus, the land depreciates. Over-cultivation has various causes and, as such, adverse effects. This article seeks to highlight this.
Causes of Over-Cultivation
Perhaps the most important cause of environmental degradation is population pressure leading to over-exploitation of land and intensified stresses on the natural resources. There is an ever-increasing number of births, which translates to increased population levels in the world. This is visible in the ever-growing count of people during censuses.
As a result, in order to sustain growth, food production must be increased.
In an effort to attain food security, governments have encouraged their residents to embrace farming to cater to the population. This high demand for food brought about by population pressure has significantly led to over-cultivation.
2. Continuous fertilizer application
This is an artificial way of improving the quality of the soil. The application of fertilizers boosts the composition of the soil with the right nutrients in the right composition. Nevertheless, this has taken a twist for the worst. There has been continuous application, which has led to the saturation of the soil.
An additional input of fertilizer does not lead to a consequent additional increase in the level of output. It is a non-linear relationship. Instead, it leads to more deterioration of the soil and thus, the point of over-cultivation.
3. Reduced agricultural land
With more people seeking land for settlement and grazing, the land available for farming has been eaten up, leaving only a small portion of the land to provide food for the increased population. Consequently, people have opted to have more seasons annually in an effort to increase food production. However, with this being done on the same piece of land, deterioration of the land is certain.
Also, there are various rules set to provide optimal conditions for crops to grow. Rules such as the space required per crop as well as the depth, have been ignored in that the space per crop is minimized to accommodate more crops, which has resulted in over-cultivation. Further to this, with a reduced number of farmlands available for farming, people have opted to encroach into forest areas where they clear the land for cultivation.
4. Continuous pesticide application
Normally, crops are affected by various pests that are specific for each crop. Consequently, pesticides are applied to reduce the invasion of pests on the crops. The application is mostly through spraying on the leaves, shoots, stems, fruits and flowers depending on the preference of the pest.
In the event of rain or overhead irrigation, the water comes into contact with the chemicals used in the pesticides and leaches in the soil. This translates into increased chemicals in the soil, which interrupts the composition of the soil, thus degrading the fertility of the soil. Just like the use of fertilizer, it leads to deterioration of the soil and thus, the point of over-cultivation.
Effects of Over-Cultivation
With no farmland, cutting of trees for lumbering is the next option. A lot of the world forest cover has deteriorated over the years due to increased human activities, especially with the population pressure increasing.
The cutting of trees is not only detrimental to the soil but may also contribute to climate change and famine. The tree roots always play a critical role in holding the soil together, therefore, preventing excessive soil erosion. Also, trees increase water retention and enhance the overall fertility of the soil.
This is the process by which previously good land gradually changes to a desert due to two primary causal agents; climate change and human activity. Over-cultivation is a progressive process characterized by the human activity of farming, which entails the clearing land. An increase in the world population means more food production.
Therefore, farming activities have to increase. However, the quest for food security has caused forest encroachment to create farming lands, which has reduced the number of trees. Consequently, water-catchment areas have gradually reduced because of deforestation, in the long-run bringing about desertification.
3. Soil erosion
There is a myriad of activities during cultivation. Examples include the clearing of land, preparation of the land, and the actual planting. All these processes entail various activities, including plowing, to enable ease in planting. Nonetheless, the action also leads to loosening of the topsoil, which is the most fertile part of the soil.
Harvesting of crops also leads to exposure of loose soil. The now loosened soil is susceptible to being easily blown away by wind or washed away by rain. This is soil erosion. Continued cultivation of land means more preparation every time the planting season is due. As a result, the soil is loosened annually, leading to more erosion facilitated by agents such as human activity, wind, and rainwater.
4. Soil degradation
Soil is the best medium for crop germination. It holds the base for essential nutrients as well as metals, which are essential for the growth of crops. Metals such as potassium, phosphorus and magnesium are only accessed by plants through soil. Over-cultivation brings about the exhaustion of these essentials.
Planting of the same type of crops season after season means that the crops previously planted exhausted the same kind of nutrients that the current crops should use. As a result of this, the current crops will then use up all the remaining nutrients and render the soil infertile. This is soil degradation. Overly cultivating means more and more nutrients are taken up, and since there is no time to replenish the lost nutrients, the value of the soil drops drastically.
5. Reduced food production
The presence of soil erosion means the most fertile soil has been eroded. In addition, over-cultivation leads to the loss of soil fertility. Consequently, with such qualities, despite the number of crops one plants annually, the output is bound to deteriorate each harvest. The application of varying inputs such as fertilizers in the farm to boost agricultural output will not change the rate of production. In the long term, this can increase and worsen the problem.
The soil has various qualities apart from a base of nutrients. In addition to this, the soil is a good water retainer. Rainwater is easily absorbed by soil. Yet, the degradation of the soil coupled with its erosion reduces its water retention capacity, thus rendering too much rainwater a danger since with no absorption, what follows is flooding.
7. Health hazard
Natural water sources are used by a large percentage of people, especially in the less developed countries. Consequently, deposition of water composed of pesticides and fertilizers in the water bodies due to soil erosion and over-cultivation is hazardous to the health of the local communities.
8. Death of marine life
Rivers end up draining their water either in lakes or in oceans. Most of these large reservoirs of water have aquatic life that thrives in such water bodies. However, when fertilizers and pesticides pollute the water at the source, the chemicals will still be present as the river drains its water.
This, notwithstanding, as the river progresses in its meander, there will be more streams that drain their water in the river. Due to over-cultivation, these streams will also increase the pollution of the main river thus, the water available for marine life will be riddled with too much chemicals that will end any hope of aquatic life.
Erosion of the soil by rainwater ends up in water bodies leading to sedimentation of rivers, lakes and coastal areas. Once the soil gets to the water sources, it leaves sediments which are detrimental to the local communities who depend on the water for their domestic use. Moreover, the sediments end up blocking up waterways in the instance of pumping water from the water resources.
Solutions to Over-Cultivation
The problem of over-cultivation can be mitigated by planting cover crops that provide vegetative cover to the soil surface, thus protecting it from the negative effects of erosion by wind or raindrops. Generally, the adverse effects of over-cultivation can be addressed through various sustainable agricultural methods.
- Crop rotation that is growing different crops each year using different nutrients that help to reduce the depletion of soil nutrients since crops that use up particular nutrients are interchanged by those that replenish these nutrients, in successive planting seasons.
- Discourage crops that increase erosion risk. For example, maize needs loads of fertilizer, and herbicide is wide rowed and harvested late, meaning that erosion can be a problem, especially on sloping land.
- Fallow periods allow the soil to rest in between planting seasons so that soil can regain its fertility.
- By plowing with the contours (shape) of the land rather than against it reduces not only water erosion but also the need for irrigation. Terraces work on the same principle; they hold water in place rather than encouraging water erosion.
- Shelterbelts/windbreaks can be used to prevent soil erosion. These are areas of forest or hedge that are left untouched to protect farmland from the effects of water and wind erosion. Shelterbelts will often appear around the outside of fields.
- Plant roots protect soil structure by holding it together and allowing air to penetrate in spaces around roots. They also encourage healthier soil communities through plant-fungal interactions. Reforesting or afforesting areas help return the land to its natural state, making it more fertile and stable, thus reducing wind and water erosion and, ultimately, land degradation.
- Though fertilizers can cause over-cultivation and eventual land degradation, they can also help to add nutrients back into the soil and allow continued cultivation.
- It is possible to water areas of land that have become arid to try the productivity of the soil. However, if the water is not used sustainably, then irrigation can cause water shortages and land degradation elsewhere.
- Restricting the number and types of animals that can graze on land, reducing the destruction of vegetation and eventual desertification.
- Population growth controlling can limit the amount of agricultural land we need and the intensity of our farming.
- Controlling urban planning that is the growth of cities and using more brownfield sites will reduce the need to deforest land areas. By keeping forest cover intact, the risk of land degradation can be reduced.
- Growing some types of vegetation is able to add nutrients back to the soil. GM crops can be engineered that withstand poor soil and water shortages. However, it might encourage people to farm on unsuitable land, causing even further land degradation.
- Organic farming does not use chemicals. If you farm organically, you are less likely to over-cultivate and reduce the soil nutrient levels, and also degrade the soil chemically. Organic matter is an essential element of soils. Applying small doses of organic matter over time encourage soil biodiversity to develop and flourish.
- Encouraging more research into how different chemicals and fertilizers affect soil biology, including in combination, make non-organic farmers aware of how severely their inputs are hampering soil health. So they can choose less damaging inputs.