Magnesium Adsorption by Bottom Soils in Ponds for Inland Culture of Marine Shrimp in Alabama. Harvey J. Pine and Claude E. Boyd Dept. of Fisheries and Allied Aquacultures Auburn University Auburn, Alabama.
Harvey J. Pine and Claude E. Boyd
Dept. of Fisheries and Allied Aquacultures
-Low-salinity shrimp culture is cultivation in waters 10 ppt or less (below 1 ppt considered freshwater) (Boyd 2002).
-Sources of low-salinity waters for inland shrimp production are typically diluted seawater or mineralized groundwater sources (Boyd and Thunjai 2002).Introduction
-The ability to produce shrimp under low-salinity conditions has allowed for its expansion to inland areas, which offers several advantages including: reduced land costs, removal from environmentally sensitive areas, and less exposure to potential pathogens
-Inland low-salinity culture (ILSC) of marine shrimp occurs in China, Ecuador, Thailand, United States, and other countries.
-In the United States ILSC of shrimp is performed in several states including Alabama, Arizona, Florida, Texas, and others.
-In Alabama ILSC of shrimp occurs in two counties (Greene and Lowndes, highlighted yellow) within the Black Belt region.
-Saline water obtained in these areas are mineralized groundwater sources with salinities ranging between 2 ppt - 9 ppt.
-Groundwater sources in these areas are deficient in certain cations and require amending with potassium and magnesium fertilizers to achieve acceptable ionic compositions and ionic ratios (Saoud et al., 2003; McNevin et al., 2004; Davis et al., 2005)
(Christopeher Boyd 2006)
(Christopeher Boyd 2006)
-Maintaining optimal potassium and magnesium concentrations are complicated by the adsorption and non-exchangeable fixation of cations (notably potassium) by the soils (Boyd et al., 2007).
-The ILSC of shrimp farms in the Black Belt region of Alabama are situated on soils that are dominated by smectitic mineralogy, which are 2:1 expansible clays that typically have high cation exchange capacity (CEC) and the ability to fix cations between adjacent layers of tetrahedral sheets.
-Continuous adsorption by these soils requires continuous monitoring of ionic concentrations and subsequent additions of fertilizers such a muriate of potash (KCl) and K-mag® (K-MgSO4).
-Three different soils from an inland shrimp farm located in Forkland, Alabama USA, were collected.
-Soils were air dried and sifted using No. 8 US standard sieve(2.36mm)
-Soil A, 3 replicates, one control
-Soil B, 3 replicates, one control
-Soil C, 3 replicates, one control
-No Soil, 3 replicates, one control
(Seawater of average composition
at 4.1ppt would have ~156 mg Mg2+/L)
Mean soil pH of exposed soils
Thank You waters (3.9 ppt salinity) from the seawater reference.