Wairau/Awatere Resource Management Plan Table P6 - General Guidelines for Salinity of Irrigation Water Class Comment Electrical TDS Conductivity (mg/L)* (μS/cm) 2 Medium-salinity water can be used if moderate 280-800 175-500 leaching occurs. Plants with medium salt tolerance can be grown, usually without special measures for salinity control. Sprinkler irrigation with the more- saline waters in this group may cause leaf scorch on slat-sensitive crops, especially at high temperatures in the daytime and with low application rates. 3 High-salinity water cannot be used on soils with 800-2,300 500-1,500 restricted drainage. Even with adequate drainage, special management for salinity control may be required, and the salt tolerance of the plants to be irrigated must be considered. 4 Very high-salinity water is not suitable for irrigation 2,300-5,500 1,500-3,500 water under ordinary conditions. For use, soils must be permeable, drainage adequate, water must be applied in excess to provide considerable leaching, and salt-tolerant crops should be selected. 5 Extremely high-salinity water may be used only on >5,500 >3,500 permeable, well-drained soils under good management, especially in relation to leaching and for salt-tolerant crops, or for occasional emergency use. Source: Hart (1974) * TDS (mg/L) = 0.68 x electrical conductivity (μS/cm). App P - 4