MANASOTA & PEACE RIVER BBDs Meeting Notebook 10-21-09.docx

B264
Citrus Irrigation Management to Increase Young Tree Growth &
Productivity on Flatwoods Ridge Soils
Project Type Basin Initiatives
AOR(s)
Water Supply, Water Quality
Basin(s) Alafia River, Hillsborough River, Peace River, Manasota
Cooperator(s)
University of Florida
Project Manager COHEN, RON
Task Manager(s)
Status Ongoing
Description
Due to Citrus Greening, Canker and labor issues the industry has had the University develop different techniques for
economical production of citrus in Florida. On of the most promising techniques, which includes high density planting
of smaller trees, was developed in Spain and commercialized in South Africa, Australia and California. This project will
develop irrigation and nutrient management recommendations for this new method of production to help conserve
water and reduce nutirent loading. Although recent citrus acres have declined District wide, it is still the largest
permitted agricultural water use. Also, with the decline in development and recent price increases, more citrus growers
are planning to expand their operations; therefore, it is important to help find ways for citrus producers to conserve
water. This water conservation project will utilize information developed in Spain and commercialized in South Africa,
Australia and California. The University will investigate and develop new cultural technology including changes to plant
density, nutrient and irrigation management. Plants will be grown with an intensive fertigation management technique
that is designed to provide essentially a non-limiting environment to those roots. This new fertilizer program will require
changes to existing irrigation management programs.
Benefits
Citrus production is the largest agricultural land use in the District. This project will help citrus producers conserve
water and reduce pollutant loading for fertilizer leaching. In addition, the information could be used by the District's
FARMS program to help design better BMP cost share systems. The amount of water saved will be a function of the
number of acres planted and their water use, which will change annually based on market and climatic conditions.
Costs
The project costs have been reduced from $182,500 to $122,300 because some of the ridge elements were removed.
Additional Information
Yield fundamentally drives profit for Florida citrus growers and is thus the key element to a grower's financial success.
Yield is tied directly to tree density and growth rate and is a simple function of numbers of trees and the related total
canopy volume over the unit area. Research over the last several decades has proven that growth of young trees and
productivity of both young and mature trees benefit from high frequency low volume irrigation. Improved tree growth
from intensive irrigation management could reduce the time required from planting to economic breakeven production,
thus provide management options in light of current devastating diseases such as Canker and Huanglongbing (citrus
greening). Florida growers have adopted Best Management Practices (BMPs) that reduce nutrient leaching by limiting
the amount of fertilizer that can be applied, and the time of year when fertilizer can be applied. These BMPs are based
on research under low-intensity management systems. However, production systems that combine grove design and
irrigation management to increase yield and grove operational efficiency have not been studied. High density plantings
of sweet oranges on low-vigor rootstocks have known advantages, but their long-term behavior and changes in the
functional relationship of tree density, growth rate, and yield over time are not well understood. The central hypothesis
of this project is improved and consistent early yields, with increased tree density on low vigor trees and/or improved
irrigation/nutrient management systems that would provide proactive management options in light of current
devastating diseases such as Canker and Huanglongbing (citrus greening). Growers normally achieve their expected
return on investment within 15 to 20 years of planting. If those goals would occur sooner (e.g., 10 to 12 years) through
increased early yields, the grower would benefit even if the grove declines over time due to the diseases mentioned
above and must be replanted. By knowing how to irrigate and manage their irrigation with this new method of
production, the grower would conserve water and reduce the amount of fertilizer thats being leached from the plant
root zone while maintaining an economical viable crop.
021 - Manasota Basin 164