Saline well water used to fill ponds for inland culture of marine shrimp in Alabama often have low concentrations of potassium and magnesium. In 2002, pond waters on a shrimp farm were treated with enough muriate of potash and potassium‐magnesium sulfate (K‐Mag) to increase potassium concentration from 6.2 mg/L to about 40 mg/L and magnesium concentrations from 4.6 mg/L to about 20 mg/L. Salinity in ponds averaged 2.6 ppt at the time of mineral salt additions. The concentrations of potassium and magnesium remained fairly constant throughout the growing season without further applications of salts, and salinity increased to about 4 ppt mainly as a result of concentration through evaporation. Survival and production on the farm averaged 19% and 595 kg/ha, respectively, in 2001. In 2002, average survival improved to 67% and average production was 4,068 kg/ha. Ponds were stocked at similar rates and managed by similar procedures both years. Magnesium concentration was very low related to the concentration expected in normal seawater diluted to the same salinity as the pond water, while potassium was near the expected concentration. Thus, increased potassium concentration is thought to have influenced production much more than did the increase in magnesium concentration. K‐Mag does not dissolve as readily as muriate of potash. Thus, K‐Mag should not be dumped in shallow water areas of ponds to dissolve as can be done with muriate of potash. It should be broadcast over the pond surface, predissolved and splashed over the pond surface, or placed in porous bags suspended in front of aerators. Although a single application of mineral salts was effective, 2002 was a dry year. On a wet year, ions may be diluted or flushed out in overflow and more than one treatment with mineral salts might be necessary during the growing season.

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The original method for determining the fineness of agricultural limestone was modified for the greater contribution of particles less than 0.25 mm in diameter that is found in the modern agricultural limestone used in aquaculture. Crusher-run limestone was screened to give nine particle size separates. Systems containing 3.0 kg of soil (pH ϭ 5.21) and 23.5 L of water (total alkalinity ϭ 0.39 mg/L) were treated with 8.0 g of each separate, and total alkalinity and pH were monitored. After 70 d, total alkalinity equilibrated at 55 mg/L in systems treated with particles less than 0.106 mm. The total alkalinity in systems treated with other particle size separates were as follows: control, 0.52 mg/L; greater than 2.0 mm, 2.28 mg/L; 2.0-0.85 mm, 5.75 mg/L; 0.85-0.42 mm, 12.25 mg/L; 0.42-0.25 mm, 26.8 mg/L; 0.25-0.15 mm, 45.62 mg/L; and 0.15-0.106 mm, 49.30 mg/L. Water pH exceeded 7.36 after 2 weeks for systems treated with particles less than 0.25 mm. Wet soil samples (2.5 kg) of pH 5.04 were placed in trays and treated with 6.7 g of limestone of different particle size separates. After 1 week, pH was 6.9-7.1 in soil treated with particles less than 0.106 mm. By 10 weeks, a pH greater than 6.5 was attained in soils treated with particles less than 0.25 mm. The pH of soil treated with particles greater than 0.25 mm was similar to the control pH. Efficiency factors were assigned to particle size-classes as follows: less than 0.106 mm, 100%; 0.25-0.106 mm, 86.7%; 0.42-0.25 mm, 49.06%; 0.85-0.42 mm, 22.4%; and greater than 0.85 mm, 7.3%. The sum of the products of the proportion of each particle size-class and the corresponding efficiency factor gave the fineness value. Fineness values usually were smaller when determined by the new method instead of the old method.