HORTICULTURE
Monitoring Blueberry Nutrition by Tissue Analysis
Eric Hanson, Horticulture, MSU
Routine Monitoring (sample every 1-3 years):
- Divide farm into sampling units with same variety (ideally), uniform soil types and past fertilization or management practices. Unit size: 1-10 acres.
- Collect 50 to 100 leaves per sampling unit in late July or early August,. Collect healthy leaves from the middle of current-season shoots from different plants throughout the sampling unit.
- Wash leaves by swirling them in a dilute detergent solution for several seconds. Rinse briefly in tap water. Let leaves air-dry on a table top.
- Package leaves in small paper bags. Send to a reputable lab for analysis of nutrient elements.
Diagnosing Problems:
To diagnose a suspected nutritional problem, collect one sample from plants developing the
problem, and a second from nearby healthy plants. Collect these samples anytime leaves are present.
Some reputable labs:
MSU Soil and Plant Nutrient Lab, A84 PSSB, MSU, East Lansing, MI 48824 (517 355-0218)
A & L Great Lakes Laboratories, Ft Wayne IN (269 483-4759,
Brookside Labs in New Knoxville, OH (419 753-2448, www.blinc.com).
Interpreting Leaf Analysis Results:
| Nutrient | Deficient | Normal | Excessive |
| Macronutrients (%) | |||
| Nitrogen (N) | Below 1.7 | 1.7 to 2.1 | Above 2.3 |
| Phosphorus (P) | Below 0.08 | 0.1 to 0.4 | Above 0.6 |
| Potassium (K) | Below 0.35 | 0.35 to 0.65 | Above 0.8 |
| Calcium (Ca) | Below 0.13 | 0.2 to 0.6 | Above 0.8 |
| Magnesium (Mg) | Below 0.1 | 0.15 to 0.3 | Above 0.4 |
| Micronutrients (ppm) | |||
| Boron (B) | Below 15 | 20-60 | Above 80 |
| Copper (Cu) | 5 to 20 | ||
| Iron (Fe) | 60 to 200 | ||
| Manganese (Mn) | 50 to 350 | ||
| Zinc (Zn) | 8 to 30 |
Nitrogen: Increase N rates by 10% for each tenth of a percent the concentration is below the deficiency level (e.g. if sample contains 1.4 % N or 0.3% below deficient level, increase rate by 30%), or decrease rate by 10% for each 0.1% the levels is above the excessive level.
Phosphorus: If deficient, use mono-amonium phosphate or di-ammonium phosphate for the nitrogen source, or apply 100 lb P2O5.
Potassium: Apply 100 - 150 lb K2O if deficient. Use potassium sulfate or potassium chloride.
Calcium: If deficient, check soil pH and apply 1000 lb lime if pH is below 4.0.
Magnesium: If deficient, check soil pH and apply dolomitic lime if pH is below 4.0. Also apply epsom salts (magnesium sulfate) at 10 lb per acre in foliar sprays in May and June.
Boron: If deficient, apply 0.5 lb B per acre in a foliar spray in June or apply 1 lb B per acre to the soil in the spring. Solubor is a good B source.
Other Resources:
MSU Extension Bulletin E-2011, Managing the Nutrition of Highbush Blueberries E-2011 in PDF
MSU Extension Bulletin E-2482, Plant Tissue Analysis for Determining Fertilizer Needs of Michigan Fruits
