Nutrient Management

Maintaining the correct amounts of nutrients in the soil and plant are essential for ensuring optimal tree growth and yield. Therefore, soil and leaf tissue analysis is necessary to monitor nutrient levels and plan fertilizer applications. Throughout British Columbia, nutrient application rates vary depending on the age and nutrient status of the orchard, variety of tree, and soil type.

Note: As new varieties are being planted in BC, more research is needed to determine the optimal leaf nutrient concentrations and fertilizer requirements for BC hazelnuts.

In hazelnut production, a soil analysis is most beneficial (1) before planting to determine nutrient and lime requirements and (2) during regular intervals in established orchards to monitor ph. Soil sampling and analysis should be completed in the late spring and fall to ensure any liming materials are given sufficient time to raise soil ph.

Application of fertilizer to established orchards is based primarily on concentrations of nutrients measured by leaf tissue analysis. Sampling of hazelnut leaves for analysis should be completed in August and sent to an analytical laboratory in a timely manner.

It is recommended that soil sampling and analysis is completed at least once every two years while leaf tissue sampling and analysis should be completed annually.

Sampling procedures

  • Soil sampling

Soil sampling and preparation instructions can be found through the BC Ministry of Agriculture publication Soil Sampling for Nutrient Management (PDF) (Publication 631-500-1).

It is important that the soil sample represent the orchard. Take soil samples from under the tree canopy, but not in the area immediately around the tree’s base. Where possible, avoid taking samples from locations where bands of fertilizer have been previously applied. Surface samples (0-15 cm) are generally sufficient for determining the need for liming materials.

In hazelnut orchards and other crops where nutrients and lime are consistently surface-applied, the top 5 cm (2 in) of soil may be significantly more acidic than the rest of the soil rooting zone after several years of surface applications. Therefore, soil from the top 5 cm of a soil sample should be separated and analysed separately from the remainder of the soil sample to determine the effect of surface applications. More information can be found in OSU Publication EM 9014 (PDF).

  • Leaf tissue

Leaf tissue samples should be taken from at least 10 trees that are representative of the orchard every August. If some trees have visual nutrient deficiency symptoms or reduced yield, then they should be sampled separately. Sample fully-developed leaves that are:

  • Near the outside of the tree
  • About head height
  • In the middle of the current season’s shoot growth

The petiole (leaf stem) should remain with the leaf. Take at least 5 leaf samples per tree. If more samples are taken on one tree, each sampled tree should have the same number of leaf samples taken.

A list of analytical laboratories for soil and leaf tissue testing can be found through the BC Ministry of Agriculture publication Nutrient Testing Laboratories (PDF) (Publication 631-500-8).

Lime should be applied if the soil pH is 5.6 or below. Liming acid soils will make phosphorus, potassium, magnesium, and some micronutrients more available to the trees and is a source of calcium. It will also provide magnesium if dolomitic limestone is used. Soil tests can determine if a lime application is necessary and how much lime to add per acre if an analysis of the soil’s Lime Buffer Capacity (LBC) is requested. It is recommended to incorporate lime into the soil root zone several weeks before planting. If lime needs to be applied to an established orchard, it should be applied in the fall to allow for movement into the soil profile and neutralization of soil acidity before the next cropping season.

Critical values for nutrients in hazelnut leaf tissue can be found in OSU Extension Publication EM 9080 (PDF). Leaf tissue concentrations should be monitored to re-evaluate the nutrient status of the tree and plan future nutrient applications.

In mature orchards, many nutrient applications are applied in a band. Banded applications of fertilizer should be placed just within the tree’s dripline to ensure proper uptake.

  • Nitrogen

Nitrogen (N) should not be applied in the first year after planting. Up to one-eighth lb N/tree can be applied in the second year as temperature-release fertilizer to avoid burning the new root system. Until the tree is mature (10-12 years old), N fertilization should be built up to the full rate. Refer to the below table for guidance on N fertilization of young trees:

Age (year)

N fertilization (lb./tree)

0-1

0

2

0.125 (only as temperature-release fertilizer)

3-5

0.25-0.33

6-7

0.33-0.5

8-10

0.50-0.75

 

Once trees have reached maturity, N rates can be increased to 1.5 to 2 lb. N/tree. If N is banded, N rates can be decreased to 1.1 to 1.6 lb. N/tree. N application should coincide with bud break, which is generally in March or April in British Columbia.

  • Phosphorus

Many soils in the Lower Mainland are high in phosphorus (P), so care must be taken to avoid over-application. Maintaining a soil pH near 6.5 will aid in maximizing soil phosphorus availability.

  • Potassium

Potassium (K) should be incorporated into the soil prior to orchard establishment. Using results from a soil analysis refer to the follow table to determine how much K (as K2O) should be incorporated prior to establishment. Note that soil test K is based on the Kelowna extractant:

Soil test K (ppm)

Amount K2O incorporation (lb/ac)

0-55

300-400

56-110

200-300

Over 110

0

Adapted from OSU Extension Publication EM 9080

 

If soil test K was determined using a different extractant, the results can be converted by following the directions described in BC Ministry of Agriculture publication Understanding Different Soil Test Methods (PDF) (Publication 631.500-9).

If the leaf tissue concentration of K is below the normal range, 6-12 lb. K2O/tree should be applied. Potassium can be applied in the fall as its mobility is limited in the soil. Applications of K should be placed in a band that is 20-30 cm (8-12 in) wide.

  • Magnesium

Magnesium (Mg) can be incorporated into the soil before establishment as dolomitic lime.  If leaf tissue analysis shows that Mg is deficient, 30-40 lb/ac of actual magnesium should be applied, generally as potassium magnesium sulphate. Epsom salts (magnesium sulphate) can also be applied at a rate of 2-4 lb. /ac. Magnesium is typically applied in the spring, concurrent with N application.

  • Boron

Boron (B) is typically deficient in Fraser Valley soils; so many producers will apply B annually in mid-May to early June. Boron has also been shown to increase nut set in hazelnut orchards, even if B is not found to be deficient.

As a foliar application, up to 5 lb. Solubor/ac (1 lb actual B/ac) can be applied to orchards greater than five years old. If leaf B is above 200 ppm, B applications should be stopped for the following year. If B is soil applied, 5-7 lb actual B/ac should be used.