SUBSURFACE MICROIRRIGATED CORN AND PEANUT - EFFECT ON SOIL-PH

A five year study was conducted to determine the feasibility of using subsurface microirrigation for a corn (Zen mays L.) grain and peanut p od (Arachis hypogea L.) production rotation system in the Atlantic Coa stal Plain region of the southeast United States. The effects of added fertilizer nutrients, chlorine, and amount of water applied to the so il on soil pH and total KCl exchangeable acidity were investigated. Th e soil was an Uchee loamy sand (loamy, siliceous, thermic Arenic Haplu dults). A total of 119 soil samples were taken from a 0.9 x 0.9 m soil profile area around the buried tubing at six sites within the researc h area to determine soil pH, total soil acidity. exchangeable Al acidi ty, and exchangeable H acidity. The value of the soil pH increased for the irrigated treatments when compared to the non-irrigated treatment . Treating the irrigation water with sodium hypochlorite to prevent em itter clogging had a net basic reaction with the soil even though 795 kg ha(-1) of N fertilizer was added to the soil during the five year s tudy. Nitrogen added to the soil through the irrigation system include d the ammonium, nitrates, and urea forms. All these forms have an acid ifying effect on soil. The total KCl exchangeable soil acidity was rel ated to exchangeable H. No exchangeable Al was detected. Exchangeable acidity patterns were similar to the pH patterns for all treatments. A pplication of chemicals through a subsurface microirrigation system do es have a major effect on soil pH. (C) 1998 Elsevier Science B.V.