Basic Knowledge in Agriculture #63
What is Soil Leaching.
Soil leaching refers to the movement of water in the soil and dissolves soluble nutrients, minerals, or chemicals which flow down into deeper layers of soils and occasionally into the ground water. This normally occurs as a result of rains, irrigation or flooding. Although leaching may serve in the removal of surplus amount of salts in soil, it also possesses adverse effects.
Critical nutrients such as nitrogen, potassium and calcium can be washed away thus decreasing the fertility of soil making it difficult to grow plants. This can cause low crop production and demand of more fertilizers in farming. Leaching can also cause the flow of dangerous chemicals in ground water e.g. pesticides or pollutants, which cause contamination. Soil leaching in total is a natural and a very powerful process that affects the soil health and quality of the environment.
Discuss the factors influencing Soil leaching.
There are various environmental and soil factors that affect soil leaching because they dictate the rate at which soil changes as a result of the washing off of nutrients and minerals in the soil. The main causes are rainfall and irrigation, whereby when the amount of rain is high or when it is over-irrigated, the water will seep down into the soil dissolving and carrying with it the nutrient of nitrogen and potassium among others.
Leaching also depends on the soil texture, since sandy soils have large pore spaces that drain rapidly and thus lead to higher leaching as compared to clay and loam soils which have longer retention times. Even the soil pH contributes to this as the acidic soils are more likely to be affected by the solubility of the nutrients and, therefore, they easily leak. Temperature also affects biochemical activity with warmer soil increasing decomposition and possible loss of nutrients. Vegetation cover and content of organic matter contribute towards the reduction of leaching by absorption of nutrients and enhancing soil structure, decreasing the speed of water movement.
What is the impact of soil leaching.
The drainage of water through soil is called soil leaching and it carries away the dissolved nutrients, chemicals and minerals. This affects the fertility of the soil since the necessary nutrients such as nitrogen, potassium, and calcium are washed away leaving the soil with reduced capacity to sustain healthy growth of plants. With the fertility depreciation, crops are weak and the yield is lower.
Environmental problems can also be the result of leaching: the nutrients that transfer to the groundwater or the rivers nearby can be polluted, such as the algal blooms that do harm their aquatic life. Also, leaching leads to the acidification of the soil that will further reduce the availability of nutrients and the soil organisms. The effects are more pronounced in sandy soils or very irrigated soils.
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