PECAN FERTILIZER NEEDS

PECAN FERTILIZER NEEDS The size and quality of pecans are influenced by the leaf-nut ratio (the number of leaves per nut). Roughly 10 compound leaves, each consisting of 9 to 13 leaflets, are required to produce and support a medium-size pecan. More are needed for large nuts. Pecan clusters are borne terminally on new shoots, and most of the leaves have already formed on a tree when the cluster develops. The soil needs to be fertile to stimulate this strong, vigorous growth and provide a generous number of leaves to support the tree and enable it to mature a good crop of pecans. All plants and animals including pecans require 17 essential elements for growth: carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn). However, most pecan research has shown increases in yield and nut quality only when a few of these elements are supplied to orchard trees. The greatest response reported has been from using nitrogen (N) on soils deficient in this element. Pecan trees are usually slow to respond to nitrogen fertilizer applications and response may not be apparent for several years, especially on fertile soils. Zinc (Zn) deficiency in pecans is well-known and occurs frequently in most pecan growing areas. Pecan trees with sufficient zinc tend to have bigger leaves than zinc-deficient trees. Foliar zinc sprays have become standard practice by most growers. Response of pecans to phosphorus (P) and potassium (K) are reported infrequently, although these elements are used by plants in relatively large amounts. Because the pecan tree’s root system invades a large volume of soil, it has been assumed that pecan trees need not receive some nutrients in large amounts, i.e., potassium, phosphorus, calcium (Ca) and magnesium (Mg). This statement is true, in general, but soils vary in chemical composition, and a nutrient believed to be at adequate levels may be lacking in some soils. Soil and leaf analyses are helpful in determining causes of a problem or potential problems. It is highly desirable to have the right nutrient levels in the tree to prevent negative effects on tree growth and yield. Soil and leaf analyses help a grower learn about the fertilizer needs of pecan trees. All of Eddy County has a high pH, this makes our soil alkaline. Because our pH is greater than 7.3 zinc and iron are not readily available as they are at lower pH. The pH in our soil cannot be changed because it is between 10- and 15 % calcium carbonate. This is what Carlsbad Caverns is made of and it act as a buffer when we add acid to our soil. We still want to use acid base fertilizer however. Some fertilizers will interact with the calcium carbonate and make the ground hard. Salt accumulation (conductivity above 4 E.C. × 103 ) will impair water infiltration and will cause stress on the trees. The application of sulfur or sulfur containing fertilizers react with the calcium carbonate to make gypsum which help improve soil structure so water can penetrate it. High sodium content (greater than 20 percent exchangeable sodium) will flocculate clay particles in soil, increase soil compaction and decrease soil permeability. When fertilizing Pecan you have to apply the right kind, at the right place, at the right time, in the right amounts. To learn about this and more come to the Eddy County Pecan Growers Round Table March 29, at 7:00 pm in the Eddy County Extension Office. If you have a disability or need special assistance contact Robin before March 27. Subscribe to Eddy County Ag news at: http://nmsueddyag.blogspot.com/ Eddy County Extension Service, New Mexico State University is an equal opportunity/affirmative action employer and educator. All programs are available to everyone regardless of race, color, religion, sex, age, handicap, or national origin. New Mexico State University, U.S. Department of Agriculture, and the Eddy County Government Cooperating.