CULTURAL TIPS: DEVELOPING A NUTRIENT BUDGET
Proper avocado‐tree fertilization is very important in sustaining yields and, to determine appropriate fertilizer amounts, routine leaf and soil analyses are annually conducted. While avocado fertilization was traditionally centered on identifying and correcting nutrient deficiencies, fertilization is being progressively replaced by proactive fertilizer programs, aimed at meeting - or exceeding - threshold‐mineral levels, while balancing nutrient levels. Therefore, a nutrient‐management plan specific to avocado groves, or blocks within groves, is needed to realize and maintain high production. A specialist is often required, when designing an avocado‐fertilizer program; however, a few recommended sites include:
- Avocado Nitrogen Model: http://www.csuchico.edu/~rrosecrance/
- California Department of Food and Agriculture's (CDFA) Fertilizer Research & Education Program: http://www.cdfa.ca.gov/is/fflders/frep.html
- University of California Cooperative Extension (UCCE) Nutrient‐Management Plan: http://groups.ucanr.org/signup/Fact_Sheets/Management_Practices.htm
Basic Elements of a Nutrition‐Management Plan (Clifford Ohmart, SureHarvest, and Stan Grant, Progressive Viticulture)
1. Developing a Nutrition‐Management Plan: Begin With Goals
• What are your management goals?
Yield, quality, sustainability, etc.?
2. Estimating Nutrient Demand for Management Unit: Field or Block
• Biomass, per acre, is proportionate to the plant‐population density
• Crop phenology: seasonal growth drives seasonal demand
• Replacement of nutrients removed with harvested crop
3. Appraising the Mineral Nutrient Supply
• Soil Analysis
Potentially available nutrients: those commonly reported = extracted nutrients
Readily available nutrients: soluble nutrients
• Contributions from soil amendments/cover crops
• Contributions from irrigation water
• For perennial crops, contributions of stored nutrient reserves and woody tissues
4. Nutrient Applications Required to Achieve Goals
• Assuming sound management, with minimum nutrient loss to environment
• Total nutrient requirement = nutrients in harvested crop - available nutrients
• Schedule applications to meet demand for growth and development (i.e. - size/quality)
5. Nutrient Economy Monitoring Guidelines
• Supply monitoring
Soil analysis
Irrigation‐water analysis
Soil‐amendment/fertilizer analysis
• Demand monitoring
Visual observations of plant condition
Plant‐tissue analysis
6. Creating a Nutrition‐Management Plan/Budget: Putting it Together
• Stated goals and keys to success
• Historical records of yields and inputs
• Nutrient sources considered
• Estimated application schedule and method for nutrient inputs = nutrient budget
• Financial budget
• Monitoring locations and guideline
• Timetable for plan review
