Archival copy. For current information, see the OSU Extension Catalog: https://catalog.extension.oregonstate.edu/em8918 NUTRIENT MANAGEMENT EM 8918 November 2006 $5.00 Nutrient Management for Blueberries in Oregon J. Hart, B. Strik, L. White, and W. Yang Archival copy. For current information, see the OSU Extension Catalog: https://catalog.extension.oregonstate.edu/em8918 Contents Growing condition assumptions .........................................................................................1 Tissue testing .......................................................................................................................2 Interpreting tissue test results ..............................................................................................3 Soil sampling ......................................................................................................................4 Site preparation ...................................................................................................................4 Nitrogen ..............................................................................................................................6 Phosphorus ..........................................................................................................................9 Potassium ............................................................................................................................9 pH and manganese ..............................................................................................................9 Calcium .............................................................................................................................10 Magnesium ........................................................................................................................10 Sulfur.................................................................................................................................10 Boron.................................................................................................................................10 Zinc ................................................................................................................................... 11 Copper ............................................................................................................................... 11 Iron .................................................................................................................................... 11 For more information ........................................................................................................12 Management points ...........................................................................................................13 Western Oregon highbush blueberry nutrient management calendar ..................back cover John Hart, Extension soil scientist; Bernadine Strik, Extension berry crops specialist; Linda White, Extension faculty, horticulture, Coos County; and Wei Yang, Extension faculty, small fruits, North Willamette Research and Extension Center; all of Oregon State University. This publication replaces FG 78, Blueberry Fertilizer Guide. Archival copy. For current information, see the OSU Extension Catalog: https://catalog.extension.oregonstate.edu/em8918 Nutrient Management for Blueberries in Oregon ommercial blueberry production in Oregon is domi- Blueberry plants require chemical elements from air, nated by the northern highbush type, although water, and soil to ensure adequate vegetative growth and rabbiteye blueberries are produced on limited acre- fruit production. When levels of these nutrients in the Cage. This publication addresses nutrient management of plant are inadequate, growth and yield may be affected. northern highbush blueberries in western Oregon. Where Severely reduced nutrient supply can lead to visible data are available to support management differences by nutrient deficiency symptoms, such as leaf discoloration blueberry type, this information is provided. (Figures 1 and 2) and distortion. The following questions are addressed in this publica- tion. These questions should be answered before any fertil- izer is applied. • How much fertilizer should be applied? • When should the fertilizer be applied (timing)? • What source (type) of nitrogen should be applied? • What method of application should be used? Growing condition assumptions In western Oregon, blueberries typically are planted in Amity, Chehalis, Colquato, Jory, Mala- bon, Nekia, Willamette, and Woodburn soils. A typical yield for a well-managed, mature field is 8 to 9 ton/a. Blueberries usually are planted at 3 ft x 10 ft Figure 1. Chlorosis caused by iron deficiency. spacing on either raised beds or flat ground. Douglas-fir sawdust generally is used as a preplant soil amendment. This guide assumes that 3.5 inches of sawdust are applied in 3-foot- wide strips on 10-foot centers and incorporated 10 inches deep before planting. Typically, con- tainer stock is planted in October, and a 2-inch surface sawdust mulch is applied. Recommendations are based on research and experience with blueberry production in this set- ting and on research in other areas. Recommenda- tions in this publication may not produce desired results in other production areas, especially in semiarid environments where soil pH is naturally above 6.0, water contains salts and carbonates, and warm winter temperatures limit the accumu- lation of chilling degrees. Figure 2. Nitrogen deficiency. Archival copy. For current information, see the OSU Extension Catalog: https://catalog.extension.oregonstate.edu/em8918 The goal of fertilization for any high-value crop is to Tissue testing can be used for any of the following: remove limitations to yield and quality by supplying the • Predicting fertilizer needs of annual crops crop with ample nutrition in advance of demand. Nutrient • Diagnosing problems application should be based on soil and plant analyses and Evaluating a fertilizer program for perennial crops grower experience. Consider the return on your fertil- • izer investment as well as environmental stewardship. A Tissue testing can be used to monitor and adjust fertil- fertilizer application should be “bio”logically sound; in izer use during early growth stages of annual crops such other words, it should produce a measurable change in as potatoes, sugar beets, or lettuce. A tissue test can help plant growth or nutrient status. A fertilizer application is growers anticipate fertilizer needs for these annual crops. expected to increase fruit yield or quality, producing a In contrast, tissue test results are not very useful for pre- return on your investment. dicting current-season fertilizer needs of perennial crops Results from a nutrient application will vary from field such as blueberries. In part, this limitation is due to the to field and from year to year. This guide does not address minimal short-term effect of fertilizer on yield in perennial every circumstance encountered by growers. Growers, crops. In producing blueberries, tissue testing is best used with the assistance of county Extension faculty and field for end-of-season evaluation of a fertilizer program. representatives, should annually consider nutrient needs If problems such as poor growth or discoloration of of each field. Routine analysis of soil and tissue samples shoots or whips appear during the growing season, you can is helpful in determining fertilizer requirements. Annual use a tissue test to check for nutrient deficiencies. When tissue testing can detect low nutrient concentration before sampling outside the late July to mid-August time period visible symptoms or yield reduction occurs. (see “When to sample,” below), you must collect a com- To assist with interpretation of soil and tissue analyses, panion sample from an unaffected area for comparison. keep records of weather, disease problems, and nutrient Tissue testing is based on sampling at the proper time, applications for each field. Observations of annual growth sampling the appropriate plant part, and using “standards” (whip number, diameter, and shoot length), yield, leaf for comparison. The following sections discuss these color, and fruit quality (berry set and firmness) are also topics. helpful. The use of fertilizer should be part of a complete man- When to sample agement package. Management practices from selection Tissue samples should be collected when nutrient con- of certified plants to pre- and postharvest irrigation must centration is stable. Samples collected just a few days apart be performed in an appropriate and timely manner so that during periods of rapidly changing nutrient concentration plants can benefit from applied nutrients. Nutrient appli- can give quite different results. For example, tissue N con- cation is not a substitute for poorly timed irrigation, late centration changes rapidly early in the growing season but harvest, or failure to control insects, diseases, rodents, or slowly after early July (Figure 3). weeds. Soil properties such as high pH and/or poor drain- For evaluation of blueberry nutrient status, collect leaf age can be significant limiting factors to obtaining high tissue between late July and mid-August. Samples col- berry yields. Increasing fertilizer rates or adding nutrients lected between these dates produce consistent analytical already in adequate supply will not correct these limiting results. factors. Tissue testing By analyzing plant tissue for nutrient content