AMELIORATION OF A CALCAREOUS SOLONETZIC SOIL BY IRRIGATION, DEEP RIPPING, AND ACIDIFICATION WITH ELEMENTAL SULFUR

Abstract

The effect of leaching, deep ripping, and acidification by bacterial oxidation of elemental sulfur on the amelioration of a calcareous Solonetzic soil over four seasons was investigated by measuring changes in soil chemical properties, infiltration, and crop yields. Weekly applications of 12–25 mm of irrigation water for 9 wk in 1981 and 11 wk in 1982 leached over half of the soluble salts from the surface 60 cm of a Solonetzic soil. Sodium was more readily leached than Ca + Mg so that the SAR was reduced from more than 20 to less than 10 throughout the surface 60 cm. Further amelioration resulted from normal irrigation practices consisting of three 4-h applications of 50–60 mm of water in 1983 and 1984. Ripping with a subsoiler to a depth of 50–60 cm did not significantly affect the reclamation but the surface infiltration rate and hydraulic conductivity remained higher 3.5 yr after tillage compared with the control. Oxidation of elemental S (3.3 t ha−1) applied in 1981 resulted in a decrease in pH of the surface 15 cm of soil from 7.2 to 5.3 after two irrigation seasons. Naturally occurring lime was dissolved by the S treatment, increasing the soluble Ca + Mg and total salts and decreasing the SAR. These effects were no longer evident after the 1984 irrigation season. Yields of spring barley (Hordeum vulgare L. ’Johnston’) were not affected by the tillage or S treatments. Key words: Solonetzic soil, sulfur, deep ripping, tillage, Thiobacillus thioparus, irrigation