Assessing Sustainability of Shrimp Aquaculture and Integration with a Field Crop

Assessing Sustainability of Shrimp Aquaculture and Integration with a Field Crop

Summary

The trial has demonstrated success in that the grove of olive trees continues to grow and mature when irrigated with effluent from the shrimp farm. Demonstration of significant differences in growth or survival, between trees irrigated with effluent, fertilized well water and plain well water has not yet been possible.

Objectives/Performance Targets

* Determine the benefits of irrigating with aquacultural effluents
* Determine any detrimental effects on soils
* Reduction of reliance on chemical fertilizers
* Efficient utilization of scarce water resources
* Organize an aquaculture field day to initiate an integrated aquaculture/agriculture extension program in Arizona

Accomplishments/Milestones

1. Determine the benefits of irrigating olives with low-salinity aquacultural effluents by measuring growth of trees.

Data has shown a slight difference among the three treatments (normal farm management of well water mixed with nitrogen fertilizer, 100% effluent and a negative control of well water with no effluent or fertilizer), no statistical difference (p=0.317) as yet, but a potential indication of long-term impacts. The experiment is being extended in hopes that additional data will demonstrate significant differences. This study plot is on previously unfarmed land, separate from the rest of the commercial farm. The fact that the trees are growing in soils that have not received fertilization for a prior crop may have led to differences in growth during this growing season compared to the first year of this project. These findings suggest that effluent improves tree growth as compared to well water, but not as much as regular fertilization.

2. Determine any detrimental effects on soil caused by the application of saline irrigation water through the monitoring of soil salinity and macro-nutrients.

Water quality

Irrigation water salinity was more similar than that observed in years past. Average salinity (ppt) for treatment groups were as follows: effluent, 1.86; fertilizer, 1.63; well water, 1.84. Source water salinity varied over time, and was at lowest levels in the spring during fertilization, explaining the lower average salinity for the fertilizer treatment. When averaged over longer treatment times, the effluent showed very little difference over well water, only increasing 0.02 ppt.

Soil Quality

Soil salinity levels did not increase significantly at the original experimental site used during year 1. At the new sample site, samples are being analyzed after each growing season. Soil sampling continues at the original site to gain a better long-term understanding of soil salinity.

3. Reduce the reliance on chemical fertilizers through close monitoring of nutrients applied and through the application of nutrient rich aquacultural effluents.

Irrigation Water

High levels of nitrate in the ground water led to higher NO3-N and total N in well water. On the second experimental plot in the third year, effluent had considerably higher levels of NH4-N and NO2-N than well water. Irrigation water quality data for the second year are listed below:

Treatment Ammonia (ppm) Nitrite (ppm) Nitrate (ppm)
Well 0.111 0.012 26.17
Effluent 0.500 0.403 22.78
Fertilizer 0.946 0.236 21.23

Leaf nutrients were also analyzed to gain a better understanding of nutrient uptake among olive trees in each treatment. These analyses showed that N, P and K were all at nearly deficient levels, with significant differences in N levels. This analysis seems to give a more complete picture of nutrient dynamics in this system.

4. Efficient utilization of scarce water resources through the multiple use of water for shrimp production and irrigation.

The 0.133-ha experimental plot contains ten rows of twelve trees. From June on, each row received 7,751 L of water each watering event, totaling 1,741 cubic meters over the course of the year. As calculated last year, enough waste water is produced on the farm to irrigate 3,270 olive trees.

5. Initiate an integrated aquaculture/agriculture extension program in Arizona by hosting an integrated agriculture field day, distributing a newsletter, developing a bulleting and web site reporting the findings of the research and attitudes of the farmers involved with the trials.

Fitzsimmons, McIntosh, King and Ryder improved working relationships with the other shrimp farms in Arizona. We provided tours to the farms for visiting scientists from Australia and other institutions.

Results of the research were presented in Louisville KY at the US Aquaculture meetings in March of 2003 and in Salvador Brazil at the World Aquaculture meetings in May, 2003. An Arid Lands Aquaculture newsletter was distributed in April of 2003.

Impacts and Contributions/Outcomes

Publications:

McIntosh, D. and Fitzsimmons, K. 2003. Characterization of effluent from an inland, low-salinity shrimp farm: what contribution could this water make if used for irrigation. Aquacultural Engineering 27:147-156.

McIntosh, D., K. Fitzsimmons, J. Aguilar and C. Collins. 2003. Toward integrating olive production with inland shrimp farming. World Aquaculture 34(1):16-20.

Fitzsimmons, McIntosh, King and Ryder improved working relationships with the other shrimp farms in Arizona. We provided tours to the farms for visiting scientists from Australia and other institutions. A major copper producer in Arizona is considering diversification into integrated shrimp and crop production. Exisiting farmers are considering expansion.

Results of the research were presented in Louisville KY at the US Aquaculture meetings in March of 2003 and in Salvador Brazil at the World Aquaculture meetings in May, 2003. An Arid Lands Aquaculture newsletter was distributed in April of 2003.

Collaborators: