Cultivated field water is desalinated by a series of independent units that float on the water surface, taking up the saline water with a wick, evaporating the water from the wick in desalinating relation by concentrating incident solar radiation with a combination of a lenses and cooperating mirrors onto the upper end portion of the wick while the wick lower end portion is immersed in the field water, capturing the desalinated vapor resulting by condensing within the unit and returning the condensed, desalinated water to the field, and periodically renewing the wick by rinsing the salt from it at a cleaning station beyond the field.