3. 



applied under the row will likely be absorbed 

 more efficiently than fertilizer spread be- 

 tween the rows. 



Choose the appropriate N fertilizer. Use 

 materials containing only ammonium-N. 

 Nitrate-N is easily leached and lost, and not 

 efficiently absorbed by blueberries. Blue- 

 berries are also quite sensitive to high levels 

 of nitrate. When using urea, remember that 

 20 to 40% of N may be lost by volatilization 

 if applied when temperatures are above 80 

 degrees and no rain or irrigation is available 

 to move the fertilizer into the soil. 

 Apply fertilizer to best match the demand of 

 the bushes. Do not apply fertilizer before 

 bud break since portions will likely be 

 leached and lost before the bushes can use it. 

 Consider splitting your fertilizer into two or 

 more applications between bud break and 

 late June. We have found split applications 

 (half at bud break, half at petal fall) provide 

 a 10% yieldincrease over a single application 

 at bud break. This work was conducted on a 



soil containing 7 to 9% organic matter. 

 Multiple applications will be most beneficial 

 on sandy, low organic soils. 

 4. Lastly, use leaf analysis to determine how 

 appropriate current N rates are for specific 

 plantings. Based on leaf samples submitted 

 to MSU each year, there is a significant 

 percentage of plantings which are receiving 

 too much fertilizer. The easiest way to 

 identify these plantings is through tissue 

 analysis. 



Fertilizer is a significant production cost, so 

 improving the efficiency of fertilization pro- 

 grams is prudent economically. Inefficient prac- 

 tices which result in fertilizer residues in rivers, 

 lakes or groundwater are a growing concern. 

 For this reason efficient use of fertilizers is 

 environmentally prudent as well. 



This article was reprinted from The 

 Great Lakes Fruit Grower, September, 

 1991. 



Fruit Notes, Fall, 1991 



