Fertilizer and Lime Calculator – Excel File

Della Deal, a former Extension Agent at the Ashe County Center of the N.C. Cooperative Extension Service, developed this Excel spreadsheet to speed the process of developing fertilizer and lime recommendations from NCDA&CS soil reports. The program first provides information to lead a grower through a decision-making process to select the best material to address indicated needs. When the nutrient recommendation from the soil report or other source is entered, it automatically calculates the amount of fertilizer needed per acre and per tree. It also shows the relative cost of different fertilizer and liming materials. While most of the calculator is protected from unintentional overwriting, highlighted fields can be changed. Thus, a grower can easily update the cost of fertilizer or liming materials he or she is interested in. Costs for all materials are provided by the ton, a 50 pound bag, and per tree by different field spacing.

The Fraser Fertilizer Requirements worksheet provides the annual nitrogen requirement based on tree size, optimum nutrient levels targeted by the NCDA&CS soil report, and the relative merit or special use of commonly available fertilizer materials. This information provides the basis for N.C. Cooperative Extension lime and fertilizer recommendations for Fraser fir Christmas trees.

The Fertilizer Calculator worksheet is where you enter the amount of fertilizer material per acre that equals the amount of nutrient recommended per acre. Adjust the amount of material per acre up or down until you achieve the recommended level of nutrient per acre. When a fertilizer material provides more than one nutrient, the calculator computes the per acre contribution of each nutrient. Address nitrogen first and then work through phosphorus and potassium requirements shown on the soil report.

Be sure not to exceed limits for the amount of material to be applied. For instance, if 350 pounds of phosphorus is needed, per acre nitrogen rates will limit the amount of 18-46-0 that can be used before you get enough phosphorus. You should only use 60 pounds of actual N (330 pounds of 18-46-0) for small trees or 100 pounds of actual N (556 pounds of 18-46-0) for 6-7 foot trees. An additional calculation for 0-46-0 will be needed to fulfill a larger phosphorus requirement (350 lb total – 255 lb from 18-46-0 = 95 lb phosphorus or 207 lb of 0-46-0).

The Cost of Fertilizer worksheet carries over the per acre rate of material from the fertilizer calculator. Here you enter the current cost of a fertilizer or liming material and it computes the cost by the ton, by 50 pound bag, and per tree by different field spacings. If you know the number of trees planted by block or farm you can use these numbers to track fertilizer and cost in the ways most useful to you.

As you use this tool, recognize that it is just a materials calculator. Fertilizer decisions may involve more information than provided in a single soil report entry. You may adjust soil report recommendations based on plant tissue analysis, a pattern across several years of soil reports, or a recommendation from your Extension Agent. You may choose to increase, decrease, or even ignore certain recommendations from the soil report. For example, a field of young trees with a well-established stand of white clover will not need the recommended nitrogen application. If you are splitting applications between spring and fall, you might only apply half of the recommended nitrogen in the spring. You might also choose to increase the amount of phosphorus to apply if you have had difficulty raising soil and tissue levels in the past.

Developing a prescription fertility plan. It is up to you to organize the calculated amounts into a usable fertility plan. Work through each field or problem area completely. You could have more than one fertilizer material and more than one liming material over the course of a year. Work to correct any deficiencies that appear on the soil report. As you work through a number of samples or different farms, you will see blocks with similar recommendations that can be grouped together for a representative treatment. However, where differences between fields are larger, it can be a mistake to combine them for the sake of convenience. The goal of prescription fertility is to optimize tree growth in each block or field.

If your trees are exhibiting poor color, growth problems, micronutrient deficiencies, or you are not sure how to address concerns beyond the soil report that you are analyzing, please contact your local cooperative extension agent with Christmas tree responsibility. Agents and specialists at NC State University can help you to determine the best course of action to address your NC Fraser fir Christmas tree fertility problems.

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension agent.

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