Salinity problems related to water quality occurs if total quantity of salts in the irrigation water is high enough for the salts to accumulate in the crop root zone to the extent that yields are affected. If excessive quantity of soluble salts accumulate in the root zone, the crop has difficult in extracting enough water from the salty soil solution. This reduces the water up take by plant and usually results in slow or reduced growth.
This problem occurs when the rate of water infiltration in to and through the soil is reduced by the effect of specific salts in the water to such extent that the crop is not adequately supplied with water and yield is reduced. The poor soil permeability causes difficulty like crusting of seedbed, water logging, and attack of disease, salinity, weeds, oxygen and nutritional problems.
A toxicity problem occurs when certain constituents in the water are taken up by the crop and accumulate in amounts that result in reduced yield. This is usually related to one or more specific ions in the water viz. boron, chloride and sodium.
Various other problems related to irrigation water quality occur with sufficient frequency and should be specifically noted. These include excessive vegetative growth, lodging and delayed crop maturity from excessive nitrogen in water supply, white deposits on fruits or leaves due to sprinkler irrigation with high carbonate water and abnormalities by an unusual pH of the irrigation water.