Jonathan W. Pote

Reduction of effluent discharge and groundwater use in catfish ponds

Abstract A management strategy designed to reduce the volume of effluent discharged from catfish ponds and decrease dependence upon groundwater was tested using a mathematical model. The approach is predicated upon the simultaneous use of certain ponds for fish production and rainwater storage. Production/storage ponds are deeper than conventional production ponds and receive overflow during rain events from other production ponds that are linked in a two- or four-pond series. The model which simulated system performance used a 26-year record of precipitation and evaporation and was based upon a computed water balance for the linked pond system. Based upon simulations representing multiple scenarios, model predictions suggested that effluent discharge may be reduced by 40–90% and groundwater use may be reduced by 40–75%. This management approach, if implemented, may be a viable method to reduce nutrient loading of receiving waters and conserve groundwater.

In situ measurement of sediment oxygen demand in catfish ponds

Abstract Sediment oxygen demand (SOD) was measured in catfish aquaculture ponds using a computer-controlled data acquisition system coupled with in situ respirometers. A total of 86 rate determinations were made in northwest Mississippi. Calculated SOD rates averaged 4·44 g/m 2 per day at an average temperature of 29°C. These rates exceeded those recorded previously in catfish ponds and may have reflected differences in pond construction and management. Location within the pond, but neither age nor location-age interaction, appeared to affect SOD.

Control of high pH in aquacultural ponds

Abstract Tests were conducted to determine the effectiveness of calcium sulfate, calcium chloride, calcium carbonate, acetic acid, and ground corn for the control of high pond pH. The tests were conducted in 24 9400 liter pools. Salts of calcium did not significantly reduce daily maximum pH relative to control pools, although mean pH levels were consistently less than control values at higher application concentrations. Acetic acid did not effectively control pH at the level tested. Application of ground corn did significantly reduce pH at all levels tested. Use of ground corn has become a routine management strategy for pH control in shrimp ponds at Mississippi State University.

Climatic criteria for land application of municipal wastewater effluent

Abstract Climatic characteristics of the coastal region require design considerations for land application systems that have been largely ignored or the bases for which have been unavailable. For example, the amount of effluent flow in a land application system increases when precipitation occurs, while at the same time the net water requirement of plants decreases. Therefore extra storage and extra land acreage is needed, but the amount required has not been established. Additionally, frequent rainfall coupled with high humidity creates an evaporation regime in the coastal region that inhibits the efficiency and viability of the land application disposal method. The bases of these problems are climatological; therefore, this study uses a climatological analysis to provide design considerations regarding the capability of this disposal method in the coastal region. The availability of long-term digitized daily weather data offers the opportunity to test the design of such systems by simulating multiple years of operation. Simulation using 30 years of weather data for a 3800 m 3 /d (1 mgd) plant in the southeastern coastal region of the United States shows that the best design requires a 256 ha (640 A) application field and a 16 ha (40 A) storage pond 3.7 m (12 ft) deep. These specifications provide system success ranging from 99% in 6 months of the year to 90% in March and prevent any failures in 90% of the years.

On-Farm Water Storage Systems in Porter Bayou Watershed, Mississippi

Since the 1970’s, groundwater levels in the Mississippi Alluvial Aquifer have decreased at a rate of approximately 100,000 acre-feet per year due to increased irrigated acres. There are roughly 13,000 permitted irrigation wells dependent on water from the Mississippi Alluvial Aquifer. Farmers and landowners are faced with two major issues with regard to sustainably managing agroecosystems in the Mississippi Delta region, namely, the declining groundwater levels in the Mississippi Delta Shallow Alluvial Aquifer, and nutrient loads into the Mississippi River and the Gulf of Mexico. Due to concerns over groundwater declines and increasing fuel costs to run irrigation pumps, farmers in the Mississippi Delta region have begun implementing irrigation conservation measures, such as tailwater recovery (TWR) ditches and storage ponds to capture irrigation and surface water runoff from the field for later use. Monitoring of two on-farm water storage (OFWS) systems at Pitts and Metcalf farms in Porter Bayou Water shed was initiated in February 2012. Water samples from storage ponds and TWR ditches were analyzed for different water quality parameters. Additional information such as water level in the TWR ditch and water weather station were recorded at 10-minute and 15 minute intervals. An inventory of installed and pending OFWS systems in Porter Bayou Watershed will be conducted as part of this study.