solarization

Solarization is a term used in two distinct fields: photography and agriculture. In photography, solarization refers to a process that partially reverses tones in an image during development, producing a characteristic edge-enhanced or inverted look. In agriculture and soil management, solarization denotes a soil disinfestation method that uses solar radiation to raise soil temperatures, suppressing weeds and soil-borne pests.

Photographic solarization, also called the Sabattier effect, occurs when a film negative or print is exposed to light briefly during development. The brief re-exposure causes exposed silver halide grains to reverse their development, resulting in areas of the image that appear lighter than their surroundings and neighboring areas with reversed tonal values. It can create high-contrast lines, halos, and a surreal appearance. The effect can be created intentionally in darkrooms or simulated in digital post-processing.

Solarization of soil involves covering moist bare soil with clear plastic sheeting during hot, sunny periods. The trapped heat raises soil temperatures to levels that kill many soil-borne pathogens, nematodes, and some weed seeds. The technique is used to manage pests in organic farming and in home gardens, typically requiring several weeks of uninterrupted sunny weather and a thick, transparent mulch. Effectiveness depends on climate, soil moisture, and duration; it is generally partial rather than complete sterilization and may be less effective for deeper pests or persistent pathogens.