Recirculating Production Pond Inflows to Increase Production and Reduce Effluents on Small-Scale Fish Farms

Final Report for OS04-018

Project Type: On-Farm Research
Funds awarded in 2004: $14,145.00
Projected End Date: 12/31/2006
Region: Southern
State: Alabama
Principal Investigator:
David Cline
Alabama Cooperative Extension System
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Project Information

Abstract:

With guidance from University personnel and funding assistance from SARE, the cooperating farmer has had the opportunity to explore the economics of recirculating water through his multi-pond production system. Recycling this water along with integrating secondary non-fish crops has helped reduce the amount of potentially nutrient rich effluents leaving the farm and allowed the farmer to increase his productivity and efficiency.

While all of the pre-determined objectives for this project were met the overall results were less than we had hoped. A number of difficulties were encountered throughout the process. There were two major factors affecting the project. First, and most difficult to manage was the weather. Over the course of the experimentation period the farm was subjected to three hurricanes and several other major weather events, including hale. This adverse weather all but ruined several crops, including both the aquaponics and terrestrial vegetables. The other major factor was the health of the farmer and his labor force. Both the farmer and the primary laborer on this project had serious health difficulties during the project. These issues prevented optimal management of the project and restricted the anticipated intensification of production in both the fish and plants arenas.

Introduction

While there are vast water resources in the Piedmont region of Alabama, only a small percentage of these water resources are being used by farmers to grow fish. Most fish farms that are outside of the major production areas such as those in East Alabama are relatively small and require diversification and/or maximum use of their on-farm resources in order to remain viable. Small farms with limited acreage are getting squeezed out by large scale industrial farms

Some fish farmers have access to spring water and flowing streams that can be used to intensify production and help them remain competitive. However, most farmers with spring water input have traditional water storage ponds (deeper than 10 feet) and much of this spring water is underutilized or just flows over the spillway. Several farmers, in an effort to further utilize this flowing water have built earthen raceways below their water storage ponds where they grow catfish and other species. This flowing water, along with aeration has allowed them to intensify their operations and help them remain competitive. One farmer has shown interest in recirculating this water back through the pond systems to “filter” it for reuse and to reduce the water effluents from the farm and possibly integrate some secondary non-fish crops in the process.

Project Objectives:

Objectives for the first year of the project included.

Installing pumps and piping
Preparing, planting and maintaining new garden plots
Constructing aquaponic rafts for use in the ponds
Stocking fish
Measuring baseline and ongoing water quality data
Recording progress

These objectives were successfully accomplished and with the exception of most of the aquaponic rafts (along with the plants) being destroyed by hurricane weather the other objectives appear to be progressing as expected. The quality of the effluent leaving the farm was well within acceptable limits and there did not appear to be a significant build up of nutrients in the ponds. With the many variable associated with this complex environmental system the direct impact of the water recirculation and additional plant production are difficult to establish.
The objectives for year two included:

Preparing the garden plots. Completing the harvest sorting and marketing of year 1 fish from raceways. Restocking the raceways with catfish. Preparing/repairing the aquaponic rafts and germinating seedlings. Feed fish and monitor their growth. Monitoring and maintaining water quality. Planting and maintaining aquaponic plant rafts. Harvest fish and plants and record the profits and losses associated with the project.

Research

Materials and methods:

With guidance from University personnel and funding assistance from SARE the cooperating farmer has been able to explore the economics of recirculating water through his pond system and has attempted to integrate secondary non-fish crops. The water recirculation helped protect environmental quality, made the most of on-farm resources and reduced the potential for releasing nutrient enriched effluents. The metabolic by-products of fish culture need not be wasted if they can be channeled into secondary crops that have economic value or benefit the primary production system in some manner. Plants are an ideal secondary crop in integrated fish/plant systems because they grow rapidly in response to the high levels of nutrients that are generated form the microbial breakdown of fish wastes. Floating rafts of aquaponic plants were placed in the most downstream pond where the nutrients would be most readily available. Water from this pond was also used to water terrestrial crops which showed the beneficial effects of the added nutrients.

The in-flowing spring water was divided into two approximately equal streams and run through two separate pond systems. In one system the spring water ran directly into the production raceway pond series and exited the property at the downstream end. In the other system the in-flowing stream was directed to a large header pond (3 acres) and then distributed from the header pond into the raceway system. When the water reached the bottom pond in this system, with the aquaponic plants, it will was allowed to settle and then pumped back to the header pond to be recycled.

Research results and discussion:

While all of the pre-determined objectives for this project were met the overall results were less than we had hoped . A number of difficulties were encountered throughout the process. There were two major factors affecting the project. First, and most difficult to manage was the weather. Over the course of the experimentation period the farm was subjected to three hurricanes and several other major weather events, including hale. This adverse weather all but ruined several crops, including both the aquaponics and terrestrial vegetables. The other major factor was the health of the farmer and his labor force. Both the farmer and the primary laborer on this project had serious health difficulties during the project. These issues prevented optimal management of the project and restricted the anticipated intensification of production in both the fish and plants arenas.

The recirculation of the water did not create any water quality problems for the fish nor was there any evidence of nutrient build up. Water quality testing indicated very little change in the quality of the water from the time it entered the property until exiting downstream. The terrestrial plants (tomatoes and peppers) seemed to thrive on the excess water from the ponds but it became evident that there were not enough nutrients in the pond water to sustain the ponds on the aquaponics rafts. The aquaponics plants did very well for a short time and then began to show signs of nutrient deficiencies. It also appeared that sunlight intensity was too much for the lettuce varieties selected and they began to show signs of burning. Small amounts of slow release fertilizers were placed in each pot on the raft in an effort to overcome the nutrient deficiencies in the water. This helped the plants to thrive longer but eventually the sun and weather rendered them unusable. The addition of the time release fertilizers did not effect the pond water to any measurable amount and water quality remained excellent throughout the study.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

The primary outreach effort of this project was a field day at Mr. Bishops farm held on May 6, 2006. We sent out a press release to several newspapers and radio stations encouraging the public to attend. We were disappointed when only 25 people attended. In addition, this project was discussed informally at several professional aquaculture meetings where people showed significant interest in the idea of floating aquaponics rafts on open ponds.

Project Outcomes

Project outcomes:

The farmer and those that viewed the process felt that the plants grown on the pond surface was a very good idea and an efficient use of space. Due to the farmers physical limitations he is planning to discontinue putting the plants in the ponds. However, as a result of this project the farmer was stimulated to move forward and build two 12’ x 100’ raceways to concentrate fish and simplify the nutrient collection. He plans to grow 40,000 pounds of fish in the raceways, collect and concentrate the nutrients, and use them to grow plants. There are a number of fish farmers all over the state that are interested in this technology and will be watching the project very closely. By moving towards a more intense system in a smaller space, they hope to improve efficiency and management effectiveness.

Economic Analysis

While the farm did produce more salable products the additional income was offset by the extra cost of recirculating the water. Without the help of the grant funding the farmer would have lost money. While 2004 and 2005 were very difficult years 2006 is looking very promising. The income generated in the first 6 months of 2006 has already matched the total income of both 2004 and 2005.

In this case, without greater intensification of production the extra expenses associated with recirculating the water was not cost effective. However, using pond water to irrigate crops appeared to be very economical.

Farmer Adoption

While many farmers were intrigued by the idea of increasing farm productivity through aquaponics and water recirculation it is too early to tell whether the practice will be adopted in other areas.

Recommendations:

Areas needing additional study

There is a current trend towards increasing intensity and efficiency on commercial catfish farms. There are several other projects underway to examine running water through a raceway and recirculating it through ponds. Others are looking at in-pond raceways. Each of these offers the ability to collect and remove nutrients from the culture system. These nutrients could be used for aquaponics plant production. More research into the specific nutrient requirement and optimization of light intensity for aquaponics plants, as well as, methods of delivering the required nutrients will move aquaponics forward. More open pond aquaponics studies would also help determine if this could be an economical and beneficial practice.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.