Using Liquid Sources of Potassium Fertilizer in Highbush Blueberry David Bryla USDA-ARS Horticultural Crops Research Unit Corvallis, OR
Consumer demand Health benefits Availability year-round New global markets
Global blueberry production 1500 1200 295,000 acres million pounds 900 600 104,000 acres Asia Pacific Med. & Africa Europe South America North America 300 0 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 From U.S. Highbush Blueberry Council
Northern highbush Lowbush ( wild ) Northern highbush Lowbush Southern highbush #1 Northern highbush Southern highbush Rabbiteye & southern highbush Rabbiteye
Fresh Market
Processed Market
Highbush Blueberry It takes about 6-8 years for a field to mature Chad Finn (USDA plant breeder) in 20-year-old Bluejay field Photo by B Strik, OSU
Blueberry is a Unique Crop Shallow-rooted [extremely fine (40 70 m) & concentrated in top 12 of soil] Acid loving [adapted to low soil ph (4.5 5.5) & high organic matter] Prefers NH 4 - over NO 3 -N [NO 3 -N is mobile in soil, whereas NH 4 -N is not] Sensitive to salinity [ammonium sulfate has a high salt index]
Blueberry
Granular fertilization riple-split application (April, May & June) Soil ph > 5.5: Ammonium sulfate (21-0-0) Soil ph < 5.0: Urea (46-0-0)
Blueberry Irrigation Most commercial blueberry fields are irrigated by sprinklers or drip Sprinklers Drip 2003: 90% of fields irrigated by sprinklers 2015: 80% fields irrigated by drip
Nitrogen Fertigation Trial Sprinklers Ammonium sulfate Drip Two lines per row (buried under the sawdust mulch) Granular fertilizer Triple-split application (April, May & June) Fertigation Weekly application (mid-april to early August)
Annual Production 20 18 16 No N fertilizer Fertigation Granular fertilizer a a b Yield (t ha -1 ) 14 12 10 8 6 4 2 b a b c a b c b c a b c 12-40% more yield with fertigation than with granular fertilizer 1 t/ha = 0 0.45 ton/acre Year 3 Year 4 Year 5 Year 6 Year 7 Vargas & Bryla (2015)
Soil solution sampler
Soil N availability 2 1 Continuous fertigation Fertigation Soil solution sampler 0 NH 4 + -N (ppm) 1000 800 600 400 Fertilizer applications Granular fertilizer Granular fertilizer 0 lb N/acre 45 lb N/acre 90 lb N/acre 135 lb N/acre 200 0 Apr May Jun Jul Aug Sep Oct 2007 Bryla & Machado (2011)
Soil salinity Electrical conductivity (ms cm -1 ) 2 1 0 8 7 6 5 4 3 2 1 Fertigation Continuous fertigation Granular fertilizer Granular fertilizer Salt burn 0 lb N/acre 45 lb N/acre 90 lb N/acre 135 lb N/acre Blueberry salt tolerance 0 Apr May Jun Jul Aug Sep Oct 2007 Bryla & Machado (2011)
Nitrogen Fertigation is the Way to Go Fertigation produces: - Larger plants - Higher yields *About 150 lb/acre N was needed in mature plants Fertigation (irrigation water + fertilizer) Weekly injection Triple-split application
Current K Guidelines 75-100 lb/acre K Soil K < 100 ppm Leaf K < 0.2% 0-75 lb/acre K Soil K = 100-150 ppm Leaf K = 0.2-0.4%
K Deficiency Drought Poor drainage Very low soil ph Heavy crop loads Sandy soil / low organic matter
K Toxicity
Using Liquid Sources of K Fertilizer Treatments: Two K sources (K 2 SO 4 and KTS) Five N sources (AS, urea, ATS, UAN, urea-triazone) Five K rates (0-0.2 g/l) Two soil types Measurements: Dry weights Leaf nutrients Soil nutrient availability
Why KTS? Acidifying agent S 2 O 3 2- H 2 S + SO 3 2- Thiosulfate reductase 2[H] Inhibits nitrification & urease activity
Soil Types Willamette silt loam (excellent) Soil ph 4.9 OM (%) 3.7 Nutrients (g/kg) Total N 1.0 P 0.1 K 0.3 Ca 0.5 Mg 0.1 Malabon silty clay loam (marginal) Soil ph 6.2 OM (%) 2.3 Nutrients (g/kg) Total N -- P <0.1 K 0.3 Ca 2.2 Mg 0.6
Soil solution sampler
Soil acidity Willamette silt loam Malabon silty clay loam 7.5 Ammonium sulfate Ammonium sulfate Soil solution ph 7.0 6.5 6.0 5.5 5.0 4.5 No K K 2 SO 4 KTS 7.5 Ammonium thiosulfate Ammonium thiosulfate Soil solution ph 7.0 6.5 6.0 5.5 5.0 4.5 0 7 14 21 28 35 42 49 56 Days after transplanting 0 7 14 21 28 35 42 49 56 Days after transplanting
7.5 Willamette silt loam Urea Malabon silty clay loam Urea Soil solution ph 7.0 6.5 6.0 5.5 5.0 4.5 No K K 2 SO 4 KTS 7.5 UAN UAN Soil solution ph 7.0 6.5 6.0 5.5 5.0 4.5 7.5 Urea-triazone Urea-triazone Soil solution ph 7.0 6.5 6.0 5.5 5.0 4.5 0 7 14 21 28 35 42 49 56 Days after transplanting 0 7 14 21 28 35 42 49 56 Days after transplanting
Soil salinity Willamette silt loam Malabon silty clay loam Soil solution EC (ds/m) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 No K K 2 SO 4 KTS Ammonium sulfate Ammonium sulfate Soil solution EC (ds/m) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 Ammonium thiosulfate Ammonium thiosulfate 0 7 14 21 28 35 42 49 56 Days after transplanting 0 7 14 21 28 35 42 49 56 Days after transplanting
Willamette silt loam Malabon sity clay loam Soil solution EC (ds/m) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 No K K 2 SO 4 KTS Urea Urea Soil solution EC (ds/m) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 UAN UAN Soil solution EC (ds/m) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 Urea-triazone Urea-triazone 0 7 14 21 28 35 42 49 56 Days after transplanting 0 7 14 21 28 35 42 49 56 Days after transplanting
Concentration of K Willamette silt loam Malabon silty clay loam Soil solution K (mg/l) 26 24 22 20 18 16 14 12 10 No K K 2 SO 4 KTS Ammonium sulfate Ammonium sulfate Soil solution K (mg/l) 26 Ammonium thiosulfate Ammonium thiosulfate 24 22 20 18 16 14 12 10 0 7 14 21 28 35 42 49 56 Days after transplanting 0 7 14 21 28 35 42 49 56 Days after transplanting
Willamette silt loam Malabon silty clay loam Soil solution K (mg/l) 26 24 22 20 18 16 14 12 10 No K K 2 SO 4 KTS Urea Urea Soil solution K (mg/l) 26 24 22 20 18 16 14 12 10 UAN UAN Soil solution K (mg/l) 26 24 22 20 18 16 14 12 10 Urea-triazone Urea-triazone 0 7 14 21 28 35 42 49 56 Days after transplanting 0 7 14 21 28 35 42 49 56 Days after transplanting
Preliminary Conclusion KTS appears promising Use with ammonium sulfate on high ph soils Use with urea on soil with optimum ph
What s Next? Two fields (good and weak) Three K sources KTS K 2 SO 4 (liquid) K 2 SO 4 (granular) No K control Measurements: Plant and soil nutrients Yield Fruit quality and storage
Thank you Technical Support Scott Orr (biological technician) Bryan Sales (graduate student) Funding Fluid Fertilizer Foundation Tessenderlo Kerley Inc. (Tom Fairweather) Oregon Blueberry Commission U.S. Dept. of Agriculture