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Nutrient Management

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Written by: 
Mary Concklin, UConn

 Fertilizer decisions for fruit crops should be made based on scientific evidence of need. This is accomplished by combining results of foliar tissue and soil testing, with environmental conditions and crop load to develop a fertilizer program.

Foliar tissue analysis indicates the levels of macro and micro nutrients within the plant tissue. Standards have been established for tree fruit.

Foliar tissue collection timing: 60 to 70 days after Petal Fall. Collect 70 to 100 of the most recent mature leaves from trees of the same variety. All labs use the sample testing method. Suggest sampling every 1 to 3 years for maintenance.

A soil analysis indicates the levels of macro nutrients (not nitrogen) and some micro nutrients available in the soil, as well as soil pH.

Soil sample collection timing: anytime the soil is not frozen. One sample will cover 10 acres unless there are changes in topography, previous fertility practices across the area have not been uniform, and if crops vary. Sample every 3 to 5 years. There are three different soil  testing methods (Morgan, Modified Morgan and Mehlich 3). All are correct. However, in order to compare a field from one testing to another, use the same soil testing lab each time.

apple nutrient foliar standards

NUtrient Foliar standard

Nitrogen (N)

2.2 to 2.4 % Hard varieties

1.8 to 2.2 % Soft varieties

2.4 to 2.6 % Non-bearing

Phosphorus (P) 0.08 to 0.33 %
Potassium (K) 1.2 to 1.8 % (higher end for Empire)
Calcium (Ca) 1.3 to 2.0 %
Magnesium (Mg) 0.35 to 0.5 %
Boron (B) 35 to 50 ppm
Iron (Fe) 60 to 400 ppm
Manganese (Mn) 35 to 135 ppm
Copper (Cu) 7 to 12 ppm
Zinc (Zn) 25 to 50 ppm
soil optimum nutrient levels (modified morgan)
nutrient optimum level
pH

6.5 to 7.0 (Non-bearing)

6.0 to 6.5 (Established)

Phosphorus (P)

>10 (Pre-plant)

9 lb (Established)

Potassium (K) 240 lb
Calcium (Ca) 2400 lb
Magnesium (Mg) 400 lb