It accumulates on the surface of leaves during overhead irrigation. It indicates the tendency of water to increase soil pH where irrigation is routinely used. In some plant-production systems, alkalinity must be neutralized to avoid increasing the soil or solution pH to a level that does not support plant growth. Hardness indicates the amount of calcium and magnesium in water and is expressed as equivalent calcium carbonate. It is useful in evaluating water quality for aquaculture and domestic uses.
High levels alert citizens to a possible well-construction problem or other environmental impact.
The recommended upper limit of NO 3 -N for human consumption is 10 ppm . Background levels of nitrate nitrogen in surface and ground water ranges from 0 to 3 ppm . Elevated nitrate nitrogen of 5 ppm or higher may indicate human-induced contamination or environmental impact. Surface and ground water analyses show how fertilizer and waste application programs affect the environment. Such records document responsible nutrient management and environmental stewardship.