Black Walnut tree leaf samples were collected and analyzed for Phosphorus, Potassium, Calcium, Magnesium, Sulfur, Sodium, Copper, Iron, Manganese, Zinc, Boron, Aluminum, and Molybdenum, using double acid extraction methods. Nitrogen was analyzed by Micro-Kjeldahl method. Results are presented in Table 2. Nitrogen content of Black Walnut trees range from 2.5-3.5 percent. If percentage decrease less than 2.0 percent serious yellowing of leaves were noticed and application of 40-50 lbs/acre actual Nitrogen are then recommended to increase the Nitrogen level in plants up to 3.0 percent.
Phosphorus is a very important element in development of Black Walnut trees. Phosphorus is an essential element in every metabolic process. A healthy Black Walnut tree will maintain 0.3 - 0.4 percent Phosphorus in leaves. Because of poor availability in soil, I strongly recommend to maintain 150-250 lbs/acre soil phosphate level and an application of 400 lbs/acre 18-48-0 or diammonium phosphate is recommended if available soil phosphate level is low or less than 50 lbs/acre in soil. Soil pH plays a major role of making phosphate fertilizer recommendations on very low pH or when pH range is 5.5 - 6.5 on application of 500 lbs/acre triple super phosphate would increase the phosphorus availability in soil and increase the phosphorus uptake for all ages of Black Walnut trees. Ranges of Calcium, Magnesium, Potassium, Sulfur, Copper, Iron, Manganese, Zinc, Boron, Aluminum, and Molybdenum are given in Table 2. Sufficiency ranges of all major elements are established and present in Table 3.
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TABLE 2: Plant tissue analysis for two, eight, and twelve year old Black Walnut Tree
|Parameters||2 Years||8 Years||12 Years|
TABLE 3: Maximum and Minumum Nutrient Concentration
in mature Black Walnut Trees. Samples collected in June,
July, August, during Growing Season.