Shrimp Farm Effluent As an Irrigation and Fertilization Source

Shrimp Farm Effluent as an Irrigation and Fertilization Source

Project Summary:

The project would examine the feasibility of using effluent from inland and coastal shrimp farms to grow field crops without soil salinization. A multi-state, multi-disciplinary team of University researchers, extension specialists and shrimp farmers will work together to determine if a sustainable farming system can be achieved. Field trials in Arizona and Texas will be matched with shrimp-plant trials in greenhouses in New Mexico and Arizona. The results of the trials will be shared with the farming and aquaculture industries through primary literature, industry publications, and extension publications. The project will be used as the basis for a Web based Arid Lands Aquaculture Center linking the three institutions, related farms and field crop and farmers from shrimp farming areas around the world.

The specific objectives of this project are:

Characterize the effluent discharged from a low-salinity shrimp farms in Arizona and Texas and evaluate this effluent as an irrigation and fertilizer source for field crops and turf grass.
Determine the economics of applying low-salinity aquacultural effluent verses traditional fertilizers to various field crops and turf grass, with adequate leaching to avoid salinization.
Explore the use of halophytes as a means of remediating coastal shrimp aquaculture effluent and providing a secondary crop.
Publish findings in extension and professional journals and develop a web-based ‘Center for Arid Lands Aquaculture’ as a forum for multiple use of water for aquaculture-agriculture in arid regions.

Team Members

University of Arizona - Lead Institution

Principal Investigator - Dr. Kevin Fitzsimmons

New Mexico State University

Principal Investigator - Dr. Walter Zacritz

Texas A&M University

Principal Investigator - Dr. Tzachi Samocha

Shrimp Farm Effluent as an Irrigation and Fertilization Source

Table of Contents

PROJECT DESCRIPTION:

This proposal addresses several topics under the FARM EFFICIENCY AND PROFITABILITY PROGRAM AREA. Specifically, (a) the project should improve management of farms integrating shrimp and irrigated field crops by reducing environmental costs and providing crop diversification; (e) provide science-based information regarding the feasibility and potential for integrated shrimp and field crops through informal education and Internet tools; (g) improve management of water resources and reduce environmental impacts of shrimp farming and soil salinization.

A. Introduction

Low-salinity groundwater is an abundant resource under many arid regions. Achieving efficient and non-injurious use of this water would make an important contribution to developing additional agricultural industries in arid regions around the world. Recent advances in the understanding of shrimp physiology have led to the development of shrimp farming in Arizona using water with Total Dissolved Solids (TDS) of less than 1500 ppm. The potential advantages of these farms are that they minimize the potential for disease transmission to or from wild shrimp, their effluents do not contaminate the marine environment and most important the nutrient enriched wastewater is being used to irrigate field crops. Farmers and investors in Arizona, California and Texas have started several inland shrimp farms. The feasibility of irrigation with low-salinity effluent and the potential environmental problems associated with effluent disposal should be carefully examined as these projects proceed.

Shrimp farming has been shown to have several environmental impacts. Coastal shrimp farming with brackish water effluents often contribute to the eutrophication of receiving waters (Paez-Osuna et al., 1998; Diergerb and Kiattisimkul, 1996). Shrimp pathogens have also been shown to be transferable in farm effluents (Lightner, 1993). New government regulations and increased awareness of the impacts of effluents on receiving waters have led to the development of new technologies and innovations to ensure that the aquaculture industry is sustainable and economically viable. Some of the recent innovations concerning effluents include pond based recirculating systems (Rosati and Respicio, 1999; Samocha et al., 1999), constructed wetlands (LaSalle et al., 1999) and decreased water discharge (Hopkins et al., 1993; Samocha et al., 1999). These innovations can significantly reduce the load of organics and metabolites in the discharge water. None of these solutions, however, provide an additional use for discharged water or the load of nutrients.

Coastal shrimp farms have been located along the Gulf of Mexico, South Carolina and Hawaii since the mid-1970's. Starting around 1980, inland saline waters were used for the commercial production of several marine species including; redfish (Fosberg et al., 1996; Fosberg and Neill, 1997), tiger prawns (Cawthorne et al., 1983: Flaherty and Vandergeest, 1998) and white shrimp (Samocha et al., 1998; Samocha et al., 1999). Advances in the understanding of shrimp physiology have led to the introduction of commercial shrimp farming to Arizona, California and Texas using water with total dissolved solids (TDS) of less than 1,500 ppm. Research results obtained by Samocha et al. (1998) indicate that penaeid shrimp can be cultured in low-salinity water (2,000 – 8,000 ppm) with survival reaching 100% and a weekly growth rate up to 1.7 grams. As, Flaherty and Vandergeest (1998) suggest, with the ability of shrimp aquaculture to utilize low-salinity water, the industry is no longer restricted to coastal regions.

Coordination of effluent discharges with irrigation and leaching requirements will determine if shrimp and field crop farming can be accomplished in a sustainable manner. Many of the farmers in the Southwest are watching the existing shrimp farms and would like to know if this multiple-use of water can be profitable and continue without damage to the soils. This project will endeavor to answer these questions and share the results directly with farmers in Arizona, California, New Mexico, Texas, and others who will be reached through publications and the website.

RELEVANCE AND SIGNIFICANCE:

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APPROACH:

The proposed project will be conducted in two separate phases, spanning a period of 24 months. Phase-one of the project will start in May 2001. The commercial ponds in Arizona and Texas and the tanks in New Mexico will be stocked with juvenile Litopenaeus vannamei. This first phase will continue until October of the same year, when the ponds and tanks will be harvested. Phase-two will be conducted during the following production season, commencing in May 2002 and running until October 2002. The interim period between phases one and two will be used to evaluate the data collected, write reports, create the web site, and make final preparations for the second phase. Similarly, the period following phase-two will be used to analyze data, write the final reports, conduct seminars, and update the web site.

Phase-one efforts, which will be conducted simultaneously by the University of Arizona (UA) and New Mexico State University (NMSU), will include demonstrations on-farm and in the lab. Researchers at the University of Arizona will be working with the commercial shrimp producers in Arizona to quantify and characterize the effluent from their farms. The volume of water added to each pond and the volume released will be monitored using flow meters to determine the water exchange rate. The water quality parameters that will be monitored include salinity (TDS and conductivity), pH, nitrogen (nitrite, nitrate and total ammonia), phosphates (total and reactive), hardness and alkalinity (as Ca), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS). These parameters will be monitored on a bi-weekly basis, beginning one-week prior to stocking and continuing until the harvest. All analyses will be conducted according to Standard Methods (A.P.H.A. 1995). The dissolved oxygen, pH, salinity, and temperature in the production ponds will be monitored by the researchers and shrimp farmers and the data will be shared as a quality check.

The demonstration will utilize four 0.1 hectare plots planted to maize, sorghum, and olives. Two plots will be irrigated with clean well water, one of which will receive chemical fertilization at a standard application rate for nitrogen. The other two plots will be irrigated with shrimp pond effluent. One of the effluent plots will receive supplemental fertilization to match the standard application rate for nitrogen.

In addition to the bi-weekly water quality monitoring, soil salinity levels will be determined. Samples will be collected at several soil depths by taking soil cores before pre-irrigation in the spring, during the heaviest irrigation in July and again after harvest. Each depth sample will be a composite collected from five locations across each demonstration plot.

NMSU’s task will involve rearing white shrimp, Litopenaeus vannamei, in low-salinity, geothermal groundwater, from on-campus wells. The animals will be stocked into 10 m3 fiberglass tanks, in a greenhouse, at a density consistent with current commercial practices (40-50 animals/m2). Shrimp tanks will be maintained in a greenhouse to better control light and temperature conditions. The water quality in the shrimp tanks as well as the inflow and outflow will be monitored weekly for nitrogen (nitrite, nitrate and total ammonia), pH, dissolved oxygen (DO), salinity (TDS and conductivity), hardness and alkalinity (as Ca) and phosphates (total and reactive). In addition to monitoring the water quality, it will be necessary to monitor the water exchange rate. This will be accomplished by recording all water added and released from each tank using a flow meter. Shrimp growth will also be monitored weekly and the feeding rate will be adjusted, accordingly. Make-up volume in the shrimp system will be adjusted on the basis of amount of effluent used for irrigation and evaporation from the tanks.

The effluent produced in the shrimp tanks will be applied to two field crops, olives and sorghum, and a Bermuda-turf grass. The plants will be grown in 20 liter lysimeters (draining pots that capture leachate fractions) inside of the same greenhouse as the shrimp. Five replicates of each plant type will be grown. Initial irrigation rate will be based on generation of a 5% leaching fraction. The first treatment is a control and will use clean, low-salinity groundwater. The second treatment will use clean, low salinity groundwater and commercial fertilizer, applied at the suggested nitrogen fertilization rates. The third treatment will use 100% shrimp effluent. The fourth treatment will use shrimp effluent supplemented with chemical fertilizer to reach standard application rate for nitrogen. Leachate fractions will be collected from all lysimeters and analyzed by treatment for nitrogen, phosphorus, and TDS as above. TSS and BOD of the leachate will not be determined as they have little relevance. Soil salinity of each lysimeter will be determined prior to planting, mid-summer and after harvest. A well-mixed sample of soil, from the entire column, will be collected from each pot so that the salinity determination includes the whole pot soil column. Plant heights of olives and sorghum will be measured on a weekly basis to record growth. Once the grass height exceeds 3 cm, electric hand clippers will be used to cut the grass and the trimmings will be weighed as an indicator of growth. Trimming will be repeated weekly to maintain the height at 3 cm. Once the optimal irrigation and fertilization rates are determined, the information collected will be used to evaluate the economic benefits of using aquacultural wastewater as a source of irrigation water and fertilizer.

At the end of phase one, total yield of shrimp and average size will be determined for the ponds in Arizona and the tank reared animals in New Mexico. Average yield of olives per tree will be determined for each treatment in Arizona and New Mexico. Sorghum yield (grams of grain per m2) will also be determined. Yield from Bermuda grass plots will be determined by the dry weight of clippings. Yield data will be analyzed using one-way ANOVA.

Phase-two will involve a second year of application of low-salinity, shrimp pond effluent to field crops in Arizona and lysimeters in New Mexico. Based on the information from the previous production season, plots will be sized and planted according to the anticipated volume and quality of the effluent. Plant growth and water quality will be monitored bi-weekly, as described above. In Arizona, soil columns will be sampled before, during and after the second harvest to determine soil salinities. Soil samples will also be analyzed from the lysimeters at NMSU on the same schedule. Increases beyond those recorded in the first year would be indicative of salinization.

Growth and yield data from shrimp and plants will be collected in the same manner as the first year. After the second harvest, the scientists from Arizona will travel New Mexico and Texas to discuss the findings with their collaborators. The seminar invitation list will include existing aquaculture operators, field crop producers from the delineated farming areas, government scientists, academics, and potential investors. The project data, analyses and conclusions will all be posted on the Center for Arid Lands Aquaculture web site. The hope is that this web site would be the catalyst to develop a forum for research and demonstration of aquaculture in arid lands that makes effective use of limited water resources.

TIME TABLE:

The duration of the project will be 24 months. The final report will be submitted in April of 2003.

Year 1 Timetable

May, 01 / June / July / Aug / Sept / Oct / Nov / Dec / Jan, 02 / Feb / Mar / Apr
Work Plan Submitted
Green House Prep. NMSU
Lay Out Field Plots (AZ & TX)
Planting
Shrimp Stocking
Data Collection
First Interim Report
Collaborators Visit AZ
Web Site Design/Creation

Year 2 Timetable

May, 02 / June / July / Aug / Sept / Oct / Nov / Dec / Jan, 03 / Feb / Mar / Apr
Green House Prep. NMSU
Planting (AZ & TX)
Shrimp Stocking
Data Collection
First Annual Report
Second Interim Report
Seminars in Texas/Cal
Web Site Update
Final Report

EVALUATION AND MONITORING:

We will use several measures to determine the success of the demonstration project.

Feedback from Arizona farms. Sharing results with our farmer cooperators will provide us with a first measure of how the information is used to either move the process forward or reconsider aspects that need further attention.
Attendance at the seminars in Texas and California. The constitution of the audience that would be attracted to the seminars and their willingness to consider the techniques will provide us with an idea of who could and would benefit from the technology.
Website hits and demand for fact sheets and reprints. We will record the requests for fact sheets and reprint requests as a measure of interest. The University of Arizona provides tracking software that provides us with a detailed analysis of website use. This report records country of origin of visitors, period of time spent at site, pages and files downloaded, referring location and numerous other parameters.
The single most important measure of success will be the number of implementers. Assuming the demonstration project provides us with a model of a successful multiple-use system for low-salinity inland aquaculture, the number of farms who incorporate the techniques developed will provide the ultimate measure of success.

DESCRIPTION OF INSTITUTIONAL SUPPORT:

The University of Arizona will be providing personnel services including support staff and student workers. Full access to the university labs will be provided in order to conduct the analyses of effluents and soils. University vehicles will also be available for instate and intrastate trips. At the Environmental Research Lab of the University of Arizona shrimp and fish culture facilities include 100 fiberglass tanks (200 l to 1,000 l), 6 steel panel tanks (4,000 l) and a variety of filters for use in recirculating systems. Also available is a 300 m2 lab containing a walk-in refrigerator, freezers, biological safety hood, incubators, and autoclave, water quality testing equipment, soil sieves, along with a source of de-ionized water.

The Southwest Technology Development Institute (SWTDI) maintains and operates the Geothermal Aquaculture facility located near the campus of New Mexico State University. This facility has two independent recirculating culture systems, each with a total system volume of over 50,000 liters. Heating and culture water are supplied from geothermal sources. SWTDI also operates the environmental systems laboratory, which performs routine water quality analyses. SWTDI also has access to the Soil, Water, and Air Test Laboratory with more advanced capabilities for soils and water analysis.