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A Look at Blueberry Fertility & Fertilizer Formulations. MASTWG February 16, 2010. David H. Hardy NCDA&CS Agronomic Division. Today’s Presentation. General overview of production Standard fertilizer program Fertility interests to pursue Challenges in blueberry fertility
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A Look at Blueberry Fertility & Fertilizer Formulations MASTWG February 16, 2010 David H. Hardy NCDA&CS Agronomic Division
Today’s Presentation • General overview of production • Standard fertilizer program • Fertility interests to pursue • Challenges in blueberry fertility • Overview of 2009 study • Future work
N.C. Blueberries 4,200 acres $3.7 million in 2007 4th largest producer in U.S. 5th highest yield in U.S.— 5430 lb/A
Highbush & Rabbiteye grown in N.C.— 80% Highbushconcentrated in Bladen, Duplin, Pender & Sampson counties
Preferred Soil pH Levels Highbush 4.0–5.0 Rabbiteye 4.5–5.3 Dr. George Cummings, 2005 N.C. Blueberry Council Proceedings
Soil types in southeastern NC may vary greatly and have a major fertility impact.
Standard Fertilizer Program • 14-28-14 @ bud break about mid-March • 100 to 150 lb per acre • 14-28-14 in early May • 75 lb per acre • 18-46-0 (DAP) in late July or early August • 50 lb per acre
Standard Fertilizer Program • Developed from work of Cummings • Older varieties • Successful and well adopted • Fertilizer relatively inexpensive
Grower Interest in Fertility • Newer variety responses to fertilizer • Star, Duke, Reveille, O’Neal
Grower Interest in Fertility Newer variety responses to fertilizer Star, Duke, Reveille, O’Neal Possible benefit from N during fruiting
Grower Interest in Fertility Newer variety responses to fertilizer Star, Duke, Reveille, O’Neal Possible benefit from N during fruiting Better use of liquid vs. dry fertilizer 5-10-5 liquid 6-12-6 liquid
Challenges in Fertility Work • Blueberry is a perennial plant • Plant takes up N in one season • Response may take several seasons • Application of fertilizer during fruiting may dislodge berries from plant • Slow release N to avoid this
Challenges in Fertility Work • Blueberries are grown on mineral and organic soils • Range of N from organic matter Leon Lynn Haven Murville Pamlico
Challenges in Fertility Work • Low soil pH may affect soil N reactions • Conversion to nitrate • Where does N go???
Blueberry N Use & Source • Fairly inefficient in using N • Ammonium (NH4+) preferred over nitrate (NO3-) • Mostly ammonium N in 14-28-14 • Studies showing higher yields with sulfur-coated urea
Research Objective in 2009 • Evaluate plant nutrition and overall plant growth • Standard dry and liquid grower fertilizers • Slow-release N products • Mixed with P and K sources to give similar rates of all nutrients
Research 2009 • Castle Hayne Station • 7 fertility treatments per row • (6 plants / treatment) • Duke, O-Neal, Star varieties • 2 rows of each variety for total of 6 rows • Variety / row = replications
Research in 2009 (7 treatments) • Control (no fertilizer) • Standard fertility (dry 14-28-14 & 18-46-0) • 5-10-5 liquid (increase efficiency by placement) Slow-release N treatments (potential increase in N availability during fruiting) • Urea • Sulfur-coated urea • Nitamin 30L (urea polymer, triazone, liquid N) • Florikan (13-13-17, 92% polymer-coated NH4+ & NO3-)
Fertilizers 14-28-14 Urea Sulfur-coated Urea Florikan
Research 2009 • Soil sampled for nitrate and fertility • 4 times (Mar 26, May 4, Jun 26, Aug 5) • Plant tissue sampled • Jun 26 • Growth • Oct 29 — measurements (H × W) • Dec 22 — pictures
Soil Fertility in Top 12 Inches • Appears to be no differences in treatments for a given depth • Note P differences between depths
Replications of Star Urea Gr. Std Dry Gr. Std Liquid S-Coated Urea Nitamin Florikan Check Urea Gr. Std Dry Gr. Std Liquid S-Coated Urea Nitamin Florikan Check
Replications of O’Neal Urea Gr. Std Dry Gr. Std Liquid S-Coated Urea Nitamin Florikan Check Urea Gr. Std Dry Gr. Std Liquid S-Coated Urea Nitamin Florikan Check
Replications of Duke Gr. Std Dry Gr. Std Liquid Urea S-Coated Urea Nitamin Florikan Check Gr. Std Dry Gr. Std Liquid S-Coated Urea Urea Nitamin Florikan Check
Thoughts on the Study One-year of data No conclusions can be drawn Considerable variability in plant growth Treatments look promising Differences may become more pronounced over the next few years Soil nitrate data puzzling Soil heavily amended with pine bark
Further Studies • Expand this study to grower fields on different soil types • Implement incubation studies in glass flasks with sampling intervals to determine N reactions at low pH • Study rock phosphate • Potential slow release of P on organic soils