How Does Soil Leaching Affect Crop Health?

:: Wednesday, October 18, 2017
When soil loses essential water-soluble nutrients needed for crop growth due to excessive rain or irrigation, the process is referred to as leaching. Depending on factors like soil structure and local climate, some soils may leach more than others. Understanding what leaching is, how it affects the environment and the health of the community, and its effects on your crops is important for farmers in every area of the world.
In particular, knowing how leaching of boron affects the overall quality and yield of your crops will provide a roadmap to improved crop yield and a healthier community and local environment.

What does leaching do to the environment?

Leaching happens when excess water, through rainfall or irrigation, takes water-soluble nutrients out of the soil. When water carries these nutrients away, they need to go somewhere.
Often, this excess nutrient-rich water flows into rivers, streams, and lakes, or is absorbed into groundwater, which may affect local community drinking water. For agriculture professionals, leaching is an environmental concern if chemical-heavy fertilizers or pesticides are washed away and make their way into water sources.

How does leaching affect my community?

Excessive leaching can cause harmful chemicals find their way into water sources that are relied upon for drinking water by local communities.
For example, when drinking water contains too many nitrates, communities are exposed to health risks. Infants and small children are most at risk because they can’t yet process the nitrates and convert them into nitrite. Without this ability, an infant’s body cannot transport oxygen via hemoglobin to all areas of the body, posing a lethal threat.

How does leaching impact my crops?

Leaching removes vital nutrients and micronutrients, such as water-soluble boron, from the soil, causing potential deficiencies in crops.
For example, when crops suffer from boron deficiency, they exhibit visual symptoms including:
  • Misshapen, thick, brittle, small leaves
  • Short stems and a "shrunken" appearance
  • Weak or dead growing points
  • Necrotic and watery patches in storage tissue
  • Cracks and splits in petioles, stems, and sometimes fruit
  • Irregular and misshapen fruit formation
  • Impaired root growth
Naturally, crop yield will be reduced.
Additionally, as nutrients leave the soil, the soil itself becomes more toxic, causing further harm to the crop, and limiting future uses for that plot of land unless the nutrients are replaced. Toxic soil means that fewer earthworms, which are essential for maintaining healthy pH levels in soil and for composting decaying leaves and plants, can survive.
Erosion is also a concern when leaching occurs in your fields. Since leaching washes away micronutrients that are required for healthy crop growth, crops aren’t able to grow strong of root systems to hold the soil in place when the next large storm or irrigation happens.

How does leaching effect boron content?

Soil condition and type affects how leaching occurs and thus affects the amount of boron available for growing crops.
For example, sandy soils that are exposed to a lot of rainfall or heavy irrigation will leach boron easier and more readily than denser soils. As such, sandier soils are likelier to need boron supplements more frequently, especially after exposure to large amounts of water. On the other hand, denser, clay-like soils tend to retain more micronutrients than their sandy soil counterparts.
To ensure the most economical use of boron supplements, your local crop consultant will likely recommend that they be added throughout the growing season, rather than once annually, to counter the effects of leaching. Because boron content is also affected by other factors such as soil pH, organic matter, and microbial activity, your consultant can perform soil testing to determine the proper level and frequency for boron application.




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U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles. Learn more about Rio Tinto.

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