John R. Pyzner, Bollich, Patricia A. | 11/9/2006 10:10:54 PM
A leaf sample is more accurate than a soil sample in determining the amount of each essential nutrient absorbed from the soil. Adequate quantity of a nutrient may be present in the soil but it may not be available to the tree. Soil pH, environmental conditions and excessive amounts of various elements in the soil can affect the availability of soil nutrients.
A leaf sample will indicate the level of specific nutrients absorbed by the tree and is the best means of accurately establishing the nitrogen and zinc levels in the tree. These two nutrients, in addition to potassium, are the three elements most often deficient in Louisiana pecan orchards.
July is the best time to take foliar samples of pecans for leaf analysis, because the leaves have matured but have not begun to decline. Leaf analysis at other stages of leaf development may not indicate the true nutritional status of a tree.
More information on leaf sample collection and preparation and on laboratories that perform analyses can be found on the Pecan Leaf Sample Collection for Nutritional Analysis page on the Horticulture and General Orchard Maintenance pages of the Pecan Station Web site. A list of laboratories that perform analysis also is available on the Pecan Leaf Sample Collection for Nutritional Analysis page. Please check with laboratories for prices of analyses.
Question answered by Dr. John Pyzner, LSU AgCenter pecan and fruit extension specialist.
The LSU AgCenter and the LSU College of Agriculture