Last month, we did a water analysis for all our bores. While most of the parameters were normal, Chloride toxicity was significant in a few borewells. Typically, an acceptable reading is of 10 meQ/L or lesser but we recorded upto 12-13 meQ/L in a few water samples.
Given the soluble nature of chloride, it is not adsorbed or held back by soils. Therefore it moves readily with the soil-water, is taken up by the crop, moves in the transpiration stream, and accumulates in the leaves. If the chloride concentration in the leaves exceeds the tolerance of the crop, injury symptoms develop such as leaf burn or drying of leaf tissue. Normally, plant injury occurs first at the leaf tips (which is common for chloride toxicity), and progresses from the tip back along the edges as severity increases. Excessive necrosis (dead tissue) is often accompanied by early leaf drop or defoliation. With sensitive crops, these symptoms occur when leaves accumulate from 0.3 to 1.0 percent chloride on a dry weight basis, but sensitivity varies across crops. Many tree crops, for example, begin to show injury above 0.3 percent chloride (dry weight). In established trees, there may not be visible effect. However, long term effects can lead to reduced yield and poor quality of fruits.
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Reducing high chloride levels can be a challenge since there is no fool proof filtration system. Since blending good quality water is often not an option where borewell is the primary source, increased application of green manure and organic matter can buffer the effects of toxicity to a considerable extent. It would be great to hear from others who have experienced chloride toxicity in their plants and were able to successfully mitigate the adverse effects. When fixed assets like borewells and soil present such constraints, knowledge to reduce such impacts becomes invaluable!
Given the soluble nature of chloride, it is not adsorbed or held back by soils. Therefore it moves readily with the soil-water, is taken up by the crop, moves in the transpiration stream, and accumulates in the leaves. If the chloride concentration in the leaves exceeds the tolerance of the crop, injury symptoms develop such as leaf burn or drying of leaf tissue. Normally, plant injury occurs first at the leaf tips (which is common for chloride toxicity), and progresses from the tip back along the edges as severity increases. Excessive necrosis (dead tissue) is often accompanied by early leaf drop or defoliation. With sensitive crops, these symptoms occur when leaves accumulate from 0.3 to 1.0 percent chloride on a dry weight basis, but sensitivity varies across crops. Many tree crops, for example, begin to show injury above 0.3 percent chloride (dry weight). In established trees, there may not be visible effect. However, long term effects can lead to reduced yield and poor quality of fruits.
Reducing high chloride levels can be a challenge since there is no fool proof filtration system. Since blending good quality water is often not an option where borewell is the primary source, increased application of green manure and organic matter can buffer the effects of toxicity to a considerable extent. It would be great to hear from others who have experienced chloride toxicity in their plants and were able to successfully mitigate the adverse effects. When fixed assets like borewells and soil present such constraints, knowledge to reduce such impacts becomes invaluable!
What made you do the water analysis? Was it the (unexplained) leaf burn or it was routine analysis that lead to its effect?
ReplyDeleteValuable information as usual. Thanks!
(Something strange about this blog entry - it says April 14. But I got e-mail today).
It is a routine thing we do every summer, when the salt concentration is more. High chloride content was suspected and the results confirmed it..
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