Section 5 5.1.1. CHAPTER 1 FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ Introduction Improving the growth and quality of balsam fir Christmas trees by applying granular fertilizers has become an important cultural practice. The types and amounts of fertilizers presently being used vary. They reflect the personal preference of growers based mainly on the visual appearance of the trees. However, using visual appearance to evaluate fertilizer requirements has several drawbacks: 1 Visual symptoms of nutrient deficiency do not appear until the deficiency is severe. 2 Damaging agents such as rodents, insects, or diseases can cause visual symptoms similar to those caused by nutrient deficiencies. 3 Visual symptoms do not indicate how much fertilizer is required to correct the deficiency. Inappropriate amounts of fertilizer may be applied. 4 Over- fertilization as a result of relying on visual symptoms is not only a waste of money, it can damage the trees. Several agencies have been working to develop a quantitative method of correcting nutrient deficiencies either by soil or foliar (leaf) analysis. Comparisons of soil and foliar analysis to several growth characteristics show that foliar analysis is the better method for determining the nutrient requirements of Christmas trees. Field work indicates that the optimum level of foliar nitrogen for balsam fir growth is about 2 per cent of the dry weight of the foliage. Fertilizer recommendations have been developed and used to design the chart in Figure 2. It is based on work done by the Canadian Forest Service Atlantic Forestry Centre, the University of New Brunswick, and the Nova Scotia Department of Natural Resources Research Division. By using foliar analysis and this chart, a grower can find out the quantities of nutrients that a particular lot requires. Collecting Foliage Samples The first step is to find out the present nutrient levels in your particular lot or lots. This is done by collecting foliage samples from each lot using the following procedure: 1 Samples should be taken in mid to late October. 2 Draw a sketch of the lot. Mark on this sketch the different site conditions that may occur within the lot such as old fields, well-drained slopes, or imperfectly drained areas. Different site conditions should be sampled separately, as nutrient requirements will vary between site types. Number each of the sites so that samples can be identified later. Section 5 5.1.2. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ 3 Within each of the site types select 10 to 15 trees to sample. Sample trees should be healthy and free of insect, disease, or animal damage. They should appear to be average trees for the site. 4 From the upper third of the crown of each sample tree clip a 4–6 inch (8–15 cm) piece of the current year’s growth. 5 Using a separate bag for each site, place the samples in a paper bag. The bag should be numbered with the number assigned to that site on the sketch drawn earlier. 6 After collecting all the samples for a site, strip the needles from the stem and place them in a plastic bag. Label the sample with the corresponding site number assigned in the sketch. Place some moistened paper towel in the bag with the needles to help keep them fresh. 7 After the samples have been collected from each site, needles stripped, and samples properly labelled, place the samples in a small box or manilla envelope and forward to the following address. Laboratory Services Nova Scotia Department of Agriculture and Fisheries P.O. Box 550 Truro, N.S. B2N 5E3 Contents: Foliage Sample 8 Remember to include a short note with your name and address, along with the statement: balsam fir foliage samples for N, P, K, Mg, Ca analysis. Whenever possible samples should be collected and mailed on the same day. Samples held for a day or two before mailing should be frozen until mailed. Most lots do not require more than three or four sample areas. Growers with a large number of samples should contact Laboratory Services in Truro at (902) 893-7444 before sending them, to ensure that the laboratory will be able to analyse them. Up-to-date information is also available on the Department of Agriculture and Fisheries website, www.gov.ns.ca/nsaf. After the analysis is completed, the laboratory will return a Foliar Tissue Analysis Report similar to the example in Figure 1. On the left side of the report you will find the sample numbers you submitted. Under the heading “Percent” you will find the percentage by weight of Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), and Magnesium (Mg) in each sample. The information from the Foliar Tissue Analysis Report allows us to use the chart in Figure 2 to determine the nutrient requirements of each sampled site. Section 5 5.1.3. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ Applying the Analysis to the Table An example best illustrates how to use the data from foliar analysis to find out how much fertilizer is recommended for each of your sample sites. We will use the first sample from the Foliar Tissue Analysis Report (Figure 1), where N = 1.65%, P = 0.19%, K = 0.81% (Ca = 0.44 and Mg = 0.07, but we don’t need those figures right now) Before using the chart, we must calculate the ratios of phosphorous to nitrogen (P/N) and potassium to nitrogen (K/N). This is done by dividing the P and K values from the analysis by the N value. FOLIAR TISSUE ANALYSIS REPORT SOILS AND CROPS BRANCH NOVA SCOTIA DEPARTMENT OF ARGICULTURE AND MARKETING TRURO, NOVA SCOTIA B2N 5E3 ____________________________________________________________________________________ To: John Doe Date received: RR #1 Balsam Road Date Reported: Evergreen, N. S. Lab Number: Figure 1 A typical foliar tissue analysis report Section 5 5.1.4. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ Calculate: P/N = 0.19/1.65 = 0.12, and K/N =0.81/1.65 = 0.49 The next step is to determine which of the N values for the three sections in the chart corresponds to the N value from your analysis. In our example, N = 1.65, which lies in between 1.6% and 2.0%, so use the middle section of N, where N is 1.6%–2.0%. Then, using the ratio of P/N = 0.12, determine into which of the three columns in the middle N section the sample falls. In our example, it is the far right column where P/N >0.1 (> is the symbol for “greater than”). The final step is to determine into which of the three rows the K/N ratio of 0.49 from the example falls. In this example it falls into the bottom row where K/N > 0.35. By following this row across to the middle section of the chart, and the P/N column down, we find that they intersect in the lower right block which calls for a fertilizer application of 3 ounces of 20–5–5 per tree. Repeat this to determine the required applications for each sample area. One thousand is a typical number of trees to be found on a wild stand in Nova Scotia. To determine the number of pounds per acre, multiply the ounces per tree by 1000 and divide by 16 (there are 16 ounces in a pound). From our previous example, this would be 3 x 1000 / 16 = 187 lb./acre. If your stocking is greater or less than 1000 trees per acre on average, use your own average stocking number instead of the 1000 figure used in the formula. Section 5 5.1.5. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ FOR STANDS UNDER 2 FEET IN HEIGHT (APPLY IN A BAND 6 INCHES FROM STEM) 17–17–17 10–10–10 OR 2 oz. 3 oz. These measures can be converted to metric units using the guide on page 5.1.7 NOTE: All recommendations are in ounces of product per tree. Figure 2 Provisional fertilizer recommendations for balsam fir from foliar analysis Fertilizers You will see from the chart that various amounts and types of fertilizer are recommended, depending on the degree of deficiency of the various elements. Fertilizers are sold as single elements or in combinations of N, P, and K. The three numbers on the label of a bag indicate the levels of N–P–K contained in that bag of fertilizer. For example, 34–0–0 is a single element fertilizer containing 34% nitrogen, no phosphorous, and no potassium. A fertilizer denoted 20– 5–5 contains 20% nitrogen, 5% phosphorous, and 5% potash (potassium). If you use a 25–5–5 mix instead of 20–5–5 as in our example, you can reduce the application rate from 3 ounces to 2.4 ounces per tree and maintain the nitrogen level. The level of P and K additions will not change significantly. The higher analysis fertilizer may be more expensive per bag, but might actually be better value when compared on an equal weight basis. Application costs may also be reduced when you have to throw less fertilizer to achieve the same nitrogen levels. Application Fertilizers should be applied in the spring usually about one to two weeks before bud burst in the balsam fir. Depending on where your lot is located, this period will usually fall in the middle three weeks of May. Fertilizers applied too early can be lost to leaching. If you apply them too late the trees will not get the full benefit. On low stocked areas, apply fertilizer around the drip line of the tree only. Otherwise, broadcast treatments are most efficient and effective. Always use caution to avoid throwing fertilizer next to the stem or allowing it to land in clumps. In particular keep the fertilizer off the trees’ foliage especially on a wet day. Aerial applications on dry days do not stick to the foliage, but wet day aerial or mechanical applications of granular fertilizers should be avoided. Vegetation Control A good vegetation management program is necessary for your trees to receive the maximum benefit of fertilizer. If competing vegetation is not controlled, less fertilizer is available to the trees. The competing vegetation will actually grow faster, suppressing your Christmas trees even more. Section 5 5.1.6. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ Deficiency Symptoms Table 1 The functions of various elements in plant growth and visual symptoms of their deficiency. Element Function Deficiency Symptoms Nitrogen Influences height growth and foliage development General yellowing of the foliage, small needles, sparse crowns Phosphorous Influences root development Purple to purplish red foliage, particularly newly developed needles associated with growing tips Potassium Influences growth of new shoots and frost hardiness Needles turn yellow at the tips. Boundary between the yellow and green on a needle is distinct Remember that similar symptoms can be caused by other damaging agents. References Bockheim, J.G. 1980. Paper delivered to Wisconsin Christmas Tree Producers Association Annual Meeting, Madison, Wisconsin, July 1980. McKill, K. 1980. Foliar Analysis A diagnostic Tool for Balsam Fir Christmas Trees. American Christmas Tree Journal (May 1980): 45–46. Krause, H.H. and W.N. Hamilton. 1983. Foliar analysis for fertilizer recommendations in Balsam Fir Christmas Tree Culture. In Balsam Fir Update: A Review of the Latest Research Findings Pertinent to Christmas Tree Culture. Proceedings of a Seminar sponsored by University of New Brunswick, Faculty of Forestry, April 1981: 42—49. Timmer, V.R. and Stone, E.L. 1978. Soil Science of America Journal 42(1): 125–130. Contributed by: Nova Scotia Department of Natural Resources Forest Research Section. Section 5 5.1.7. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON FOLIAR (LEAF) ANALYSIS ___________________________________________________________________________________ APPENDIX 1 CONVERSIONS OF TRADITIONAL AND METRIC MEASURES _________________________________________________________________________________ These conversions are approximate, and are intended only as a guide. For more precise conversions, consult official sources. Length centimetres to inches........................... inches to centimetres........................... feet to metres...................................... metres to feet...................................... kilometres to miles.............................. miles to kilometres.............................. multiply by................. multiply by................. multiply by................. multiply by................. multiply by................. multiply by................. 0.39 2.54 0.30 3.28 0.62 1.61 Area square feet to m2................................. m2 to square feet................................. acres to hectares.................................. hectares to acres.................................. multiply by................. multiply by................. multiply by................. multiply by................. 0.09 10.76 2.47 0.40 Volume/Capacity imperial gallons to litres...................... litres to imperial gallons...................... multiply by................. 4.55 multiply by................. 0.22 Weight grams to ounces.................................. ounces to grams.................................. kilograms to pounds........................... pounds to kilograms........................... multiply by................. multiply by................. multiply by................. multiply by................. 0.03 28.35 2.20 0.45 Section 5 5.2.1. CHAPTER 2 FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON CHARACTERISTICS _______________________________________________________________________ When nitrogen fertilizer is spread beneath a balsam fir, the tree responds to this increase of available food by growing faster and producing longer needles. In the following year it will produce more and larger buds (Figure 1). Needles become a darker green, and the stomata the twin rows of white breathing pores on the underside of the needles become whiter and conspicuous. You can see this best by flicking a branch upward on a sunny day, when a silvery flash is reflected off the stomata in the sunlight. Survival of the current year’s buds is higher, and the life span of the individual needles is prolonged. For the Christmas tree producer all these changes mean a more attractive and densely foliated tree either directly or in combination with shearing. The problem is to decide what fertilizer to use, when to apply it, and how much. What Fertilizer? The fertilizer to use in the Maritimes is ammonium nitrate or urea for a nitrogen source. Each has its advantages. Ammonium nitrate is more stable but more bulky, requiring more volume per pound of actual nitrogen than urea. Urea will be lost to the atmosphere when exposed to sunlight. When to Apply? Fertilizer should be applied from mid-May to June. Applied too early, the nitrogen will be leached from the soil by early spring rains and melting snow, and carried away in the groundwater before it can be used. Applied too late, it will prolong the needle-growing period and cause premature needle drop in late fall as a result of frost kill. Section 5 5.2.2. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON CHARACTERISTICS _______________________________________________________________________ Figure 1 Average responses of balsam fir one year after broadcast treatment of nitrogen. How Much To Use? The ideal range of fertilizer application rates is 165–275 lb./acre (185–310kg/ha) of ammonium nitrate, or 122–203 lb./acre (135–228 kg/ha) of area depending on the growing qualities or needs of the site. In relating these weights to the pounds of nitrogen used in Figure 1, remember that ammonium nitrate is only 34 per cent actual nitrogen by weight, so that 275 pounds (125 kg) of purchased ammonium nitrate is actually just over 90 pounds (40 kg) of nitrogen. Ideal application rates and expected results for a range of sites are shown in Figure 2. To use this chart, first examine the area to be treated, and decide if it can be divided into separate sections according to the rate of growth and general appearance of the trees. Then sample within each area to determine an index of needle length, by selecting one lateral shoot at breast height on the south side of each sample tree. Section 5 5.2.3. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON CHARACTERISTICS Pluck ten needles from the shoot, and measure the longest needle (see Figure 2). Sample ten trees, and average the results to obtain an index of needle length that will serve as a convenient indicator of site quality for balsam fir Christmas trees. Remember, the plan is to fertilize the trees and not the site! Broadcast treatments of ammonium nitrate: Treatment 1 = 275 lb./acre; 4.5 oz. per tree (at 1,000 trees/acre) Treatment 2 = 220 lb./acre; 3.5 oz. per tree (at 1,000 trees/acre) Treatment 3 = 165 lb./acre; 2.5 oz. per tree (at 1,000 trees/acre) Broadcast treatments of ammonium nitrate (in metric units:) Treatment 1 = 310 kg/ha; 125 g per tree (at 2500 trees/ha) Treatment 2 = 250 kg/ha: 100 g per tree (at 2500 trees/ha) Treatment 3 = 185 kg/ha: 70 g per tree (at 2500 trees/ha) Section 5 5.2.4. FERTILIZER: WILD STAND RECOMMENDATIONS BASED ON CHARACTERISTICS Figure 2 Measurement of length of longest needles at the centre of a lateral shoot. What about Potassium and Phosphorous? According to studies at the Canadian Forest Service Atlantic Forestry Centre, balsam fir Christmas trees do not respond to large applications of phosphorous or potassium. But each time trees are harvested some of these nutrients are removed with the foliage and in theory should be put back. We do not know the exact amount required, but from other studies we have calculated that 60 pounds (27 kg) each of triple super-phosphate and potassium sulphate will more than replenish the lost nutrients, if applied at least every four years. Alternatively, a mix such as 20–5–5 can be applied at 300 lb./acre (336 kg/ha) every second year or 150 lb./acre (168 kg/ha) every year. Expectations Great and Small On average, the Christmas tree producer can expect to add 0.04–0.2 inches (1–5 mm) to needle length. This can in theory increase density usually by about 10 per cent and in some cases by as much as 20 per cent. The number of internodal buds can be increased from as few as 6 per shoot to anywhere from 16 to 30. A darker green colour can almost always be expected. However except for colour change some trees will not respond to fertilizer. This may be as many as 20 per cent of the trees treated at the higher rate and as many as 30 per cent at the lower rate. Variation will be greatest at the higher rate. Conditions in wild stands vary more than in plantations on cultivated land, so that trees side by side are often growing in quite different situations. A tree on a hummock, for example, is mostly growing on the remnants of an upturned root of some long-since fallen tree. Its neighbour growing in the adjacent hollow persists on thin soil left when the roots were torn from the ground. However, in spite of this variability of wild stands, the Christmas tree producer operating in a wild stand can gain some comfort from the certainty that the wild site he has selected is capable of growing balsam fir. Contributed by: D. G. Embree and G. F. Estabrooks Canadian Forest Service Atlantic Forestry Centre P.O. Box 4000, Fredericton New Brunswick, E3B 5P7 Section 5 5.3.1. CHAPTER 3 FERTILIZATION OF YOUNG TREES ___________________________________________________________________________________ Root Systems Phosphorous enhances root growth, and nitrogen is important for top growth and colour. Too much nitrogen will promote excessive top growth compared to root development. This is especially apt to happen in high-density seedbeds, where space for roots to grow is limited. Note that balanced fertilizers are recommended in seedling production. A tree overfertilized with nitrogen will have poor caliper (stem thickness), and will be tall but spindly. Shoot elongation is complete by mid-July, but root growth is greatest during August through to October. Fifty per cent of seedling weight is actually accumulated after early August. Colour A nitrogen deficiency can be most easily identified by a light green to yellow colour in the needles. A magnesium deficiency is very similar to nitrogen deficiency and is identified by yellowing of foliage near the apex of the shoots. If you are unable to obtain magnesium supplemented fertilizer (typically 10–10–10+Mg), sulpha-mag (epsom salts or magnesium sulphate) may be substituted and used at a rate of 100–200 lb./acre (112–224 kg/ha). Winter Hardiness Potassium stimulates hardening-off the physiological process a plant goes through to prepare itself for winter. Caution: using too much nitrogen forces top growth too late into the year. The seedlings do not then harden off in time to avoid fall frost damage. Stem Canker When fertilizers are manufactured it is difficult to completely eliminate the presence of salts. A build up of salts at the soil level can lead to stem canker. To prevent excessive salt levels, avoid overfertilization. Seedbed and Transplant Bed Fertilization Granular fertilizers burn foliage and tender young roots. To protect roots, do not apply fertilizer too soon when seedlings are just starting. To prevent foliage burn, remove any lodged granules from the seedling tops. For first year seedlings, a light watering will dislodge any trapped granules. For second year seedlings, a light brushing with hand, broom, or branch will suffice. Several applications over the season will result in better growth than a single application in the spring. If colour or growth are poor, analysis of a foliage sample will help diagnose the problem. If the plants become too spindly, decrease the fertilizer rate the soil is rich enough to supply the seedlings nutrient requirements. Section 5 5.3.2. FERTILIZATION OF YOUNG TREES ___________________________________________________________________________________ First Year Seedlings (Rising 1+0) Do not top dress with granular fertilizer too early. Wait six to eight weeks after the seedlings germinate and use complete fertilizers (fertilizers with all three major nutrients present). A standard recommendation for balsam fir is to apply 150 lb./acre (170 kg/ha) of 10–10–10+Mg in July and August. This program can be further enhanced by replacing 10–10–10 with 0–20–0 granular fertilizer in early August to promote root growth, and then 0–20–20 in late August and September to promote both root growth and winter hardiness. Table 1 FERTILIZATION SCHEDULE FOR RISING (1+0) BALSAM FIR SEEDLINGS Timing June 10–15 July 5–15 July 25– Aug 5 Sept 1–5 Fertilizer Formulation 10–10–10+Mg 10–10–10+Mg 0–20–0 0–20–20 Amount per 100 sq.ft. of Seedbed 6 oz. 6 oz. 6–8 oz. 6–8 oz. These measures can be converted to metric units using the guide on page 5.1.7 A generalized table for other seedling species is included for those wishing to grow species other than balsam. Divide the quantity in ounces by the number of applications recommended per year to determine the correct quantity for each application. These measures can be converted to metric units using the guide page 5.1.7 Section 5 5.3.3. FERTILIZATION OF YOUNG TREES ___________________________________________________________________________________ Second Year Seedling (Rising 2+0) The roots of second year seedlings are better established and at less risk of fertilizer burn. Fertilization may begin earlier in the year. These measures can be converted to metric units using the guide on page 5.1.7. Transplants Roots are not firmly established after transplanting, so several light applications, 200 lb./acre (225 kg/ ha) of 10–10–10+Mg should be made during the first summer in June, July, and August. In the second year applications should be started in April. Fertilization of Container Seedlings For container stock it is best to use soluble fertilizers. Two types commonly available are 10–52–10 and 20–20–20. Other specific forestry formulations of soluble fertilizer are available. For first year seedlings apply 2–3 ounces of fertilizer over 100 square feet (6.5–9 g/m2) in enough water to carry the fertilizer into the soil. Many growers fertilize and then immediately irrigate to achieve penetration. Start with 10–52–10, two to four weeks after germination. Later, during active vegetative growth, use 20–20–20, and later in the year harden off with 10–52–10 again. Applications should be made weekly and continued until late August or into September. After the first year, the dosage rate can be increased to 3–4 ounces per 100 square feet (9–12g/m2) of container space. It should still be applied weekly. Section 5 5.3.4. FERTILIZATION OF YOUNG TREES ___________________________________________________________________________________ Soluble Fertilizers Water soluble fertilizers though perhaps too expensive to consider for large-scale plantation use can be economical for use on seed and transplant beds. Many horticultural crops can absorb nutrients directly through their foliage when soluble fertilizers are applied with mist blowers. We don’t yet know for certain if foliar fertilization is truly practical for conifers with their waxy needles. Soluble fertilizers are a good source of trace elements, and many nurserymen apply soluble fertilizers as a supplement to granular mixes. Forestry seedlings can show iron deficiency under normal fertility programs. If peat moss is used extensively as a planting medium without mixing in lime, magnesium can become limiting as well. Specific forestry soluble fertilizers are available with chelated trace elements added to the major three of N, P, and K. Common added trace elements include magnesium, iron, manganese, zinc, copper, boron and molybdenum. When purchasing soluble fertilizers, try to ensure that pure, high grade components are used, to cut down on the soluble salts that will also be in the mix. As mentioned before, a build up of salts at soil level can lead to stem canker. Soluble fertilizers are available in different ratios of N, P and K. Starter mixes such as 11–41–8 are heavier in phosphorous to support very young developing roots. Later, during the period of active vegetative growth, more balanced mixes such as 20–20–20 or 20–8–20 are recommended. To harden seedlings off in the fall, mixes lower in nitrogen and phosphorous, such as 8–20–30 are used. This helps to eliminate soft growth too late into the year. Starter fertilizers are applied from two weeks after germination until the eighth week of growth. Balanced mixes should be used in June and July. In the second year of a seedling’s development, a balanced mix can be used earlier in the year, in place of the starter mix. Finishing mixes should be used in August, and can be begun in late July. These measures can be converted to metric units using the guide on page 5.1.7. Section 5 5.3.5. FERTILIZATION OF YOUNG TREES ___________________________________________________________________________________ Fertilizing Young Outplants A seedling taken to the field or cultivated wild lot for final planting is known as an outplant. Regular granular fertilizer applications during the year of outplanting are not recommended the trees are not well enough established and fertilization could damage them. Typically the associated herbicide treatment of a planting program will release sufficient nutrient for the outplants. Fertilizer applications the year following planting are effective, and much safer. A granular fertilizer such as 17–17–17 (2 ounces or 55 g per tree) or 10–10–10 (3 ounces or 85 g per tree) should be applied in a band 6 inches (15 cm) from the stem of young outplants. When fertilizing small trees, greater caution must be used to ensure the correct rate is applied and the fertilizer is not applied within 6 inches (15 cm) of the stem. Use a cut down measuring cup that holds the correct amount of fertilizer to ensure the correct amount is applied. Recommended Reading Growing Your Own Seedlings by Don Levy, available from Nova Scotia Department of Natural Resources.
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