FACTORS AFFECTING RESPIRATION IN DRY POND BOTTOM SOILS

The potential influence of drying, liming, tilling, bacterial augmentation, and nitrogen fertilization on respiration of pond bottom soil exposed to air between crops was evaluated in laboratory studies using soil respiration chambers. The optimum soil moisture concentration for respiration was 12-20%, and further drying decreased soil respiration. Soil respiration was greatest at pH 7.5-8.0, and both calcium hydroxide and calcium carbonate were effective in enhancing respiration of acidic soil. Pulverization of soil to eliminate the hard surface crust formed on drying accelerated respiration, thus tilling of pond bottom soils would be expected to increase respiration. Nitrogen fertilization showed some benefit to soil respiration, but there was no value in bacterial augmentation. These laboratory findings provide background information useful to pond studies on bottom soil treatments.