ABSTRACT
Limestone usage in the US increased rapidly after the initiation of Federal Agricultural Conservation Programs in 1936. Historically, lime needs have been based on previous experience, soil type, pH, soil texture, and/or interactions among these factors. Research has shown that soil pH, total acidity, texture, organic matter, crop to be grown, weathering stage of soil, and depth of plowing influence amount of lime required. Gypsum and Sulfur materials are used as both fertilizers and soil amendments. A soil in which the sodium-adsorption ratio of the saturation extract is 15 or more is considered to be a sodic soil. These soils contain sufficient sodium to reduce plant growth due to dispersion of soil colloidial materials, resulting in reduced air and water movement. Gypsum and sulfur are among the materials which can be applied to amend the soil. This results in the replacement of sodium on the exchange complex which is subsequently leached.
