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Soluble salts are not leached from these soils, and in some cases they build up to levels that curtail plant [49] and microbial growth. [50] Soil profiles in arid and semi-arid regions are also apt to accumulate carbonates and certain types of expansive clays ( calcrete or caliche horizons).
Sodium fluoride (NaF) is an inorganic compound with the formula Na F.It is a colorless or white solid that is readily soluble in water. It is used in trace amounts in the fluoridation of drinking water to prevent tooth decay, and in toothpastes and topical pharmaceuticals for the same purpose.
Soluble fluoride salts, of which sodium fluoride is the most common, are toxic, and have resulted in both accidental and self-inflicted deaths from acute poisoning. [4] The lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg elemental fluoride per kg body weight).
Plants absorb water-soluble inorganic salts only from the soil for their growth. Soil as such does not lose fertility just by growing crops but it lose its fertility due to accumulation of unwanted and depletion of wanted inorganic salts from the soil by improper irrigation and acid rain water (quantity and quality of water).
Detrimental effects on plant growth and yield; Damage to infrastructure (roads, bricks, corrosion of pipes and cables) Reduction of water quality for users, sedimentation problems, increased leaching of metals, [6] especially copper, cadmium, manganese and zinc. Soil erosion ultimately, when crops are too strongly affected by the amounts of salts.
Plants are exposed to many stress factors, such as drought, high salinity or pathogens, which reduce the yield of the cultivated plants or affect the quality of the harvested products. Although there are many kinds of biotic stress, the majority of plant diseases are caused by fungi. [ 4 ]
It has been found that food contamination from fertilizer is of little concern as plants accumulate little fluoride from the soil; of greater concern is the possibility of fluoride toxicity to livestock that ingest contaminated soils. [98] [99] Also of possible concern are the effects of fluoride on soil microorganisms. [98] [99] [100]
Consequently, the widespread use of phosphate fertilizers has increased soil fluoride concentrations. It has been found that food contamination from fertilizer is of little concern as plants accumulate little fluoride from the soil; of greater concern is the possibility of fluoride toxicity to livestock that ingest contaminated soils.