This type of system does not address nutrient leaching to groundwater unless the floor or soil is rendered impervious to water or irrigation efficiency is improved. Salinity management strategies include, blending recycled and fresh water, grouping plants by relative salt-tolerance, selection of appropriate fertilizer materials and rates and irrigation management. Salinity runoff will increase with each irrigation cycle. The actual blend percentage in the nursery is often dictated by water storage and use considerations. The percentage increase in salinity per cycle depends on evaporation rate, leaching fraction and degree of salt loading from soil mix components and fertilizer applications.
Salinity is monitored by determining conductivity of collected runoff and of the blended supply.
In liquid feed programs appropriate fertilizers are added either to achieve a target EC or ppm nutrient. Since nutrients often account for a significant portion of the salinity it is important to regularly analyze the recycled water for nutrient content. Specific-ion electrodes can be used at the nursery to determine nitrate and potassium levels. Adjustment of pH can be accomplished by mineral acid, or ammonium or potassium hydroxide addition. Specific ion toxicity can be of concern.