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Reaction of Liming Materials in Pond Bottom Soils 10ER1

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Reaction of Liming Materials in Pond Bottom Soils

Effluents and Pollution Research 1 (10ER1)/Experiment/Brazil and South Africa

Collaborating Institution
Embrapa Meio Ambiente, Brazil
     Julio F. Queiroz

University of the North, South Africa
     Jacobus Prinsloo
     Andrew Scholtz
     Johan Theron

Auburn University
     Claude E. Boyd
     Wesley Wood

Objectives
1) Determine the influence of lime application method on total alkalinity and total hardness of pond water.

2) Determine the influence of application method on depth to which agricultural limestone reacts in pond bottom soils of different texture.

Significance
Liming of ponds to neutralize acidity of bottom soils and to increase the total alkalinity and total hardness of pond waters is a well-established practice (Boyd, 1974, 1982; Boyd and Tucker, 1998). Methods for determining lime requirement of pond soils are available and commonly used for determining liming rates (Boyd, 1995). However, there is still no consensus on whether it is more effective to apply liming materials to the bottoms of empty ponds or to wait and apply them over the water surface after ponds are filled. There is also little information on how deep lime reacts in pond sediment over time (Boyd and Cuenco, 1980), and whether the depth of reaction is different when liming materials are applied to the water or to the soil. Also, the influence of soil texture on depth of lime reaction has not been studied, and the possible benefit of tilling pond bottoms on the depth of lime reaction has not been evaluated. The proposed research will provide answers to these questions about pond liming with bottoms of sandy soil or of clayey soil.

The work described here relates directly to research priorities outlined under the Pond Dynamics Research Theme Description. Results of this experiment will provide knowledge on proper application of a commonly used management practice (liming) on exchange of substances between and within soil and water. Improved liming practices are critical to development of effective pond management techniques.

Quantified Anticipated Benefits
When this work is complete, data will be available for coarse textured (South Africa) and fine textured (Brazil) soils regarding the influence of lime application method on neutralization of acidity in ponds. These data will allow us to formulate recommendations on appropriate application methods to maximize effectiveness of lime applied to aquacultural ponds. Beneficiaries of results obtained in this research effort include not only farmers near CRSP sites, but those in neighboring countries as well. Moreover, this experiment will be valuable in solving pond-soil acidity related problems in the US baitfish, channel catfish, and sportfish industries. One PI (C.E. Boyd) has soil projects funded by the Southern Regional Aquaculture Center in the U.S., and this study will complement that effort.

Research Design
Location of Work : Pietersburg, South Africa, and Jaguariuna, Brazil

Pond Facilities: Ponds for use in this work will be ponds on private fish farms in the vicinity of Pietersburg, South Africa, and Jaguariuna, Brazil. These ponds are 2,000 to 5,000 m2 in area with average depth of about 1 m.

Culture Period: Brazil: September 2001 through May 2002; South Africa: May 2002 through January 2003

Test Species: Tilapia

Stocking Rates: The stocking rate is not critical to the experiment, and it will be determined by the farmer.

Nutrient Inputs: Feeds and fertilizers will be applied according to the judgment of the pond manager. Liming materials will be applied according to treatments described below.

Water Management: Static ponds with water entering following rainstorms. Water will only be added to replace evaporation and seepage losses.

Treatments: All ponds will be treated with agricultural limestone at a rate sufficient to satisfy the lime requirement of the soil (Boyd 1995). There will be four treatments, each applied to three ponds, each as follows:

Sampling and Analyses: Core samples of 20-cm length will be collected from ten locations in each pond with a 5-cm diameter core tube before ponds are limed and at 1-month intervals until harvest. The cores will be cut into 2-cm long segments as described by Munsiri et al. (1995). The soil samples will be oven dried at 60°C in a forced-draft oven. Samples will be pulverized to pass a 40-mesh screen. Soil pH will be measured in 1:1 mixtures of dry soil and distilled water (Thunjai et al., 2001). Exchangeable acidity will be measured by the change in pH caused by adding 5 g soil to 10 ml of buffer solution (Adams and Evans, 1962). Samples taken at the beginning and end of crop will be analyzed for free calcium carbonate (Nelson, 1982). Water samples will be collected from ponds at weekly intervals and analyzed for total alkalinity (acidimetry) and total hardness (EDTA titration) as described by Boyd and Tucker (1992).

Statistical Design and Data Analysis: The null hypotheses to be tested are that the methods of lime application (over water surface or spread over empty bottom) do not differ in their effects on soil pH and exchange acidity and that tilling will not influence the penetration of lime into the bottom soil. The experiment at each location will be arranged as a split-split plot with lime application method (4) as main plots, soil depths (10) as sub-plots, and time (number of sampling dates: 10 for soil pH and exchangeable acidity, 10 for water alkalinity and hardness, and 2 for soil free calcium carbonate) as sub-sub-plots. Each plot/sub-plot/sub-sub-plot combination will be replicated three times. Thus, a total of 12 ponds (four main plots ¥ three replications) will be required to conduct the experiment at each location. Data collected will be subjected to analyses of variance, testing for all main effects and interactions. A probability of greater F (P > F) equal to 0.1 will be used to determine significance of treatment effects. Least significant difference will be used to separate treatment means.

The data will be evaluated to determine the depth and rate at which the liming material reacts with the soil by determining in each pond if there are increases in pH, and decreases in exchangeable acidity between adjacent 2-cm layers in each pond. The free calcium carbonate analysis will be used to determine how much limestone remains unreacted at the end of the crop.

Regional Integration
This project integrates well into the regional plans for Africa and South America. The information obtained will be useful for identification of appropriate lime application methods for local conditions in countries surrounding PD/A CRSP sites.

Schedule
September 2001 - Apply treatments and collect initial soil and water samples in Brazil
September 2001 through May 2002 - Collect monthly soil and weekly water samples in Brazil
May 2002 - Apply treatments and collect initial soil and water samples in South Africa
May 2002 through January 2003 - Collect monthly soil and weekly water samples in South Africa
September 2001 through March 2003 - Laboratory analysis of collected samples
April 2003 - Submission of final report

Literature Cited
Adams, F. and C.E. Evans, 1962. A rapid method for measuring lime requirement of red-yellow podzolic soils. Soil Science Society of America Proceedings, 26:355­357.

Boyd, C.E., 1974. Lime requirements of Alabama fish ponds. Alabama Agriculture Experiment Station, Auburn University, Alabama, Bulletin 459, 19 pp.

Boyd, C.E., 1982. Liming fish ponds. Journal of Soil and Water Conservation 37:86­88.

Boyd, C.E., 1995. Bottom Soils, Sediment and Pond Aquaculture. Chapman and Hall, New York, New York, USA.

Boyd, C.E. and M.L. Cuenco, 1980. Refinements of the lime requirement procedure for fish ponds. Aquaculture, 21:293­299.

Boyd, C.E. and C.S. Tucker, 1992. Water Quality and Pond Soil Analyses for Aquaculture. Alabama Agricultural Experiment Station, Auburn University, Alabama, 183 pp.

Boyd, C.E. and J.R. Bowman, 1997. Pond bottom soils. In: H.S. Egna and C.E. Boyd (Editors), Dynamics of Pond Aquaculture, CRC Press, Boca Raton, Florida, pp. 135­162.

Boyd, C.E. and C.S. Tucker, 1998. Pond Aquaculture Water Quality Management. Kluwer Academic Publishers, Boston, 700 pp.

Munsiri, P., C.E. Boyd, and B.F. Hajek, 1995. Physical and chemical characteristics of bottom soil profiles in ponds at Auburn, Alabama, and a proposed method for describing pond soil horizons. Journal of the World Aquaculture Society 26:346­377.

Nelson, D.W. and L.E. Sommers, 1982. Total carbon, organic carbon, and organic matter. In: A.L. Page, R.H. Miller, and D.R. Keeney (Editors), Methods of Soil Analysis, Part 2, Chemical and Microbiological Properties, American Society of Agronomy, Madison, Wisconsin, pp. 539­579.

Thunjai, T., C.E. Boyd, and K. Dube, 2001. Pond soil pH measurement. Journal of the World Aquaculture Society 32: in press.

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