Florida Research Center for Agricultural Sustainability

Sustainable Citrus Program

The Florida Research Center for Agricultural Sustainability (FLARES) has developed and is implementing a Sustainable Citrus Program (SCP) for the citrus groves located within the Merritt Island National Wildlife Refuge (MINWR) for the United States Department of Interior, Fish and Wildlife Service (FWS). The primary goal of the SCP is to reduce the impact of agricultural chemicals and practices used in the MINWR citrus groves to the adjacent waters of the Indian River Lagoon (IRL) System. The SCP at the MINWR citrus groves allows the grove management practices to meet the current Environmental Protection Agency's (EPA's) requirement to eliminate the use of toxic or environmentally harmful pesticides on national wildlife refuges. In particular, the environmental benefits of the SCP addresses the EPA�s National Estuary Program and State of Florida�s Surface Water Improvement and Management (SWIM) Program goals to attain and maintain water and sediment of sufficient quality to support a functioning macrophyte based ecosystem that supports endangered and threatened species, fisheries and wildlife.

The implementation of a sustainable agricultural system that is inherently environmentally benign is of utmost importance to the "sustainability" of the MINWR in view of the nine threatened species and sixteen endangered species of flora and fauna located within its confines. The second goal of the SCP is to demonstrate the economic and agricultural feasibility of sustainable agricultural practices in citrus groves on a commercial scale. The challenge is that the management program for these citrus groves must be economically viable to assure continued agricultural activity into the future. Perhaps the greatest benefit to be derived from this program will be its potential incorporation by citrus growers throughout the state of Florida, thereby effecting a tremendous impact on the environment statewide.

The use of Geographical Information Systems (GIS) coupled with GPS technologies developed for citrus management, tree counting, disease monitoring, tree growth rates could equally be used by the MINWR to identify areas of concern based on environmental parameters such as areas of sensitive habitat for wildlife and flora. GIS/GPS can be used to predict where specified habitats occur.

The agricultural and environmental benefits derived from the SCP in terms of reduced chemical and pesticide use, improved surface water quality, and increased water conservation would be enormous if adopted by the state�s citrus growers. It is anticipated that the close proximity of the MINWR citrus groves to the highly visible space program at the Kennedy Space Center will provide increased visibility to the FLARES� environmentally sensitive citrus management program and stimulate grower acceptance statewide. This is perhaps the greatest benefit to be derived from this program. To illustrate this benefit further, one can easily conceive the environmental advantages if this program were adopted by as little as 10% of Florida�s 850,000 acres of citrus.

Description of the Six Key Agricultural Components

Fertility Management

The SCP uses two progressive methods of fertility management in citrus: foliar fertilization and the application of organic matter. Foliar fertilization is the application of appropriate fertilizers to a plant�s foliage for assimilation and use by the plant as a source of nutrients. The application of organic matter not only serves as a source of nutrients, but also improves soil quality by increasing the water and nutrient holding capacity and suppresses some bacterial and fungal diseases. Both these fertility practices can reduce the amount of nutrients entering the IRL as well as other water bodies located near citrus. Very high levels of soil phosphorus of 75 ppm (weak Bray method) found in the MINWR citrus groves make ground applications of this primary nutrient unnecessary and wasteful. Moreover ground applications of phosphorus can cause nutrient loading in surface water entering the IRL.

Some of the nutrients for foliar application will come from the onsite recycling of a scrubber solution used to wash the oxidizer fuel from the space shuttle at the KSC. A process reacts the nitrogen tetroxide oxidizer fuel with hydrogen peroxide and potassium hydroxide to produce potassium nitrate which is a common, commercial fertilizer. This process solves two problems. First it eliminates a KSC hazardous waste stream by producing a useful fertilizer and second, it provides a cheap source of nitrogen and potassium that can be foliarly applied to citrus reducing production costs. Twenty-five percent of the total nitrogen and potash per acre will be applied by foliar fertilization. The balance of the nutrients (75%) will be applied as organic matter as either compost, manure, or Urban Plant Debris (UPD).

The SCP currently in use at the Kerr Center�s Florida Research Center for Agricultural Sustainability (FLARES) has allowed a 60% reduction of the University of Florida�s recommended rates (0.3 lb. N/box) for nitrogen without affecting yield. Ground applications of commercial dry fertilizer will be used initially until the sourcing and application infrastructure of compost is developed. However, no ground application of phosphorus or muriate (chloride) fertilizers will be used.

Water Management

The heart of the water management program is the establishment of a well-maintained drainage system. This will address the major problem of these citrus groves. Active pumping will occur only when necessary. The construction of reservoirs to provide water to the trees during dry periods will be coordinated with NASA officials. Irrigation frequency will be based on soil moisture as determined by tensiometers and water table monitoring wells. Water and soil samples will be taken regularly to monitor the effects of the SCP on the MINWR groves.

Insect and Disease Management

Insect and disease management is accomplished by utilizing environmentally benign pest control strategies such as biological control and Integrated Pest Management (IPM) practices. The Kerr Center applies its proprietary expertise with non toxic sprays to suppress pests. Pest control sprays are based on the use of highly refined petroleum oil. Bio-rational fungicides are combined with foliar fertilizers to suppress pests and provide nutrients. This combination of spray materials results in an effective and cost efficient spray mixture that both fertilizes and controls pests in a single spray application.

Waste Management and Nutrient Recycling

Waste management and nutrient recycling is accomplished by applying compost obtained from local composting facilities. This compost will be produced from wastewater treatment solids, food waste, seafood waste, manure, and horticultural waste. Recycling of waste in this fashion increases soil fertility, decreases landfill inputs and decreases fertilizer costs. In addition, numerous scientific references document the use of compost to suppress soil pathogens affecting citrus roots.

Weed Management

Weed management in the SCP consists of the use of FLARES' Low-Rate Herbicide Program which has been published as a fact sheet. This program has previously lowered herbicide costs up to 20% and has eliminated the use of pre-emergent herbicides.

Biological Diversity

The SCP relies on the application of a basic ecological principle applied to agricultural systems that biological diversity leads to stability in ecological systems. The fact that the citrus groves are surrounded by native habitats with diverse flora and fauna that also act as a refugia for beneficial organisms offers a tremendous advantage toward achieving a successful biological control program.

Geographical Information System (GIS)

We are using a Geographic Information System (GIS) to help us manage, assess, and monitor these citrus groves. The foundation for the GIS views of the groves are the digitized Black and White ortho images from a general survey overflight executed in July 1995 by NASA. Since these aerial images are geo-referenced, they allow us to determine the exact positions for individual citrus trees, roads, hammocks, buildings, drainage ditches, wells, pumps, as well as agronomic data i.e. acreage, yield, soil types, soil pH, tree variety, etc. By using subsequent aerial images we can detect changes in tree canopy growth, condition, mortality, and generally update our imagery with both biotic and physical changes occurring over time. Our GIS files and views have been provided to the citrus growers at the MINWR, FWS, St. John�s River Water Management District and the Brevard County Soil and Water Conservation Service.

Benefits

The primary benefit of the Sustainable Citrus Program (SCP) is the validation of a sustainable citrus management program that is agronomically beneficial and economically profitable to the grower while not contributing any adverse impacts to the waters of the Indian River Lagoon System by either nutrients or pesticides. The implementation of the SCP at the Merritt Island National Wildlife Refuge (MINWR) citrus groves meets both the US Fish and Wildlife�s Pest Management Policy and Responsibilities (30 AM 12) and the Department of Interior�s Pest Management Policy (Dept. Manual, Part 517-1) requirements to eliminate the use of toxic or environmentally harmful pesticides within National Wildlife Refuges. In addition, the environmental benefits of the SCP addresses the EPA�s National Estuary Program and Florida States� Surface Water Improvement and Management (SWIM) Program goals to support and maintain a pristine ecosystem equivalent to that which existed in the early 1900's, prior to the present development of the region. The integration of a sustainable agricultural system that is environmentally benign is of utmost importance to the sustainability of these pristine and historic citrus groves in view of the nine threatened species and sixteen endangered species of flora and fauna located within the confines of the refuge. Perhaps the greatest benefit derived from the SCP would be its incorporation by citrus growers in the coastal region thereby significantly reducing agriculture�s impact on the Indian River Lagoon System and assuring its viability.