Session 9. Microirrigation Alternatives to Limited Water Supplies
Reclaimed Municipal Water for Citrus Irrigation in Florida
L. R. Parsons, T. A. Wheaton, P. Cross
Use of treated municipal wastewater or reclaimed water has increased in Florida since 1986. A number of projects use reclaimed water for irrigation of food crops, ornamentals, golf courses, and residential areas. This paper reviews the use of reclaimed water in the Water Conserv II project, the largest agricultural irrigation reclaimed water project of its type in the world. Located west of Orlando, Florida, Water Conserv II presently irrigates over 3000 hectares of citrus. Reclaimed water has been successfully there for more than 7 years. Water from treatment facilities in Orlando and Orange County is pumped 25 km to a distribution center in an agricultural area in western Orange County and southeastern Lake County. A highly instrumented computerized system controls pumps and valves and monitors the operation of the system. From the distribution center, a system of pipes supplies reclaimed water at no cost to the grower to the edge of his property. Excess reclaimed water is disposed of in rapid infiltration basins (RIBs) which are areas of rapid percolation. Water quality standards were established at the beginning of the project, and continued extensive sampling insures water of excellent quality for irrigation. Groves on reclaimed water generally appear to be in better condition than similar groves irrigated with well water. This reclaimed water is probably not an important source of nutrition for most elements, but does supply all the calcium, phosphorous, and boron required by the trees. No problems have developed as indicated by monitoring of soil and leaf mineral content in citrus groves over a period of 7 years. Landowners were initially skeptical about using reclaimed water, but are now eager to have its availability expanded. Reclaimed water, but are now eager to have its availability expanded. Reclaimed water, once considered to be a disposal problem, may become a limited resource.
Keywords: Wastewater, Effluent, Microsprinkler, Citrus, Conserv II
Abstract taken from paper found on pages 262 to 268 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG
Irrigating with Reclaimed Water Through Permanent Subsurface Drip Irrigation Systems
Elson C. Gushiken
In Hawaii, reclaimed water has been used in agricultural irrigation and the irrigation of golf courses and other large landscaped areas. However, the Hawaii Department of Health's new "Guidelines for the Treatment and Use of Reclaimed Water" published in November 1993, limits uses of reclaimed water through overhead sprinkler irrigation systems. The subsurface drip irrigation concept provides a unique opportunity to effectively address the issues of reclaimed water management and disposal while providing for irrigation needs. This paper discusses the design, implementation and management of two permanent subsurface drip irrigation projects in Hawaii using reclaimed water in accordance with the state's new reuse guidelines.
Keywords: Reclaimed water, Wastewater, Reuse, Disposal, Subsurface drip irrigation
Abstract taken from paper found on pages 269 to 274 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG
Deficit Irrigation of Microirrigated Tomatoes and Citrus on High Water Table Soils
T. A. Obreza and D. J. Pitts
Increasing population and expanding irrigated agriculture has increased demand on the available water supply in southwest Florida, inducing some growers to convert to microirrigation. Irrigation water-use cut-backs, imposed by regulatory agencies during drought periods, may have greatest impact on crops grown with efficient irrigation systems. The objective of this study was to determine the effect of irrigation reductions (deficit irrigation) on citrus and tomato fruit yield and quality. Irrigation cut-backs of 33 and 50% (citrus), and 15 and 30% (tomato) below a well-watered condition were imposed for two crop seasons. Estimated evapotranspiration (ET), rainfall, irrigation volumes, soil water tension, shallow water table depths, disease severity, citrus and tomato yields, orange juice quality, and tomato fruit size distribution were measured. Irrigation cut-back did not affect citrus yield or juice quality. Well-distributed rainfall (no rain-free periods longer than 3 weeks) and a water table 100 cm deep minimized irrigation impact. Irrigation cut-back increased tomato plant water stress and disease susceptibility, and decreased yield of extra-large fruit. A 130 cm-deep water table had minimal effect on the tomato water requirement. An imposed irrigation cut-back on microirrigated tomatoes could cause serious economic impact through loss of crop marketability.
Keywords: Deficit irrigation, Microirrigation, Citrus, Tomato, Water table
Abstract taken from paper found on pages 275 to 280 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG
Drip and Spray Irrigation of Citrus Orchards in Israel
Most of the citrus orchards in Israel are currently irrigated with partial wetting of the soil surface--either by drip or by spray systems. Drip irrigation is most common on the heavier loessial and alluvial soils of the inland valleys, while spray irrigation is practiced on the sandy and sandy loam soils of the coastal plain. The components of the annual water balance (transpiration, evaporation, and drainage) are evaluated quantitatively in relation to the climatic conditions occurring in the regions: excess winter rainfall and a long dry irrigation season. Strategies to minimize drainage losses below the root zone are reviewed. The partition of evapotranspiration between evaporation and transpiration is the main point of discussion. Several long-term irrigation experiments comparing different irrigation methods are reviewed. The conclusion of this review is that water losses by evaporation from the bare soil and by deep drainage can be minimized by water application below the tree canopy and by proper management of drip, microjet or spray irrigation.
Keywords: Citrus, Drip, Microjet, Water balance, Drainage, Transpiration, Evaporation
Abstract taken from paper found on pages 281 to 287 in Proceedings of 5th International Microirrigation Congress, April 2-6, 1995, Orlando, Florida. American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085-9659, USA. Phone: 616-429-0300 FAX: 616-429-3852 EMAIL: HQ@ASAE.ORG