Cool Season Vegetables and Strawberry Response to Phosphates Research and Observations over the last Ten Years David Holden
Introduction My Experience Over 700 trials in the past ten years in nutrient and pest management for fruit, nut, and vegetable production. Over 35 trials in the past ten years with phosphate based fertilizers on vegetables, strawberries, grapes, and trees.
Introduction All phosphate trials were conducted in the coastal counties of Monterey, San Luis Obispo, Santa Barbara, and Ventura Both ortho and poly phosphates were involved. Sometimes organic acid additives were involved, along with phosphorus protecting products.
University Recommendations University of California, ANR Publication 8098, Nutrient Management In Cool Season Vegetables
What are the Issues with ph Phosphorus Availability Temperature Cation inhibition Calcium Zinc Etc.
How Soil ph affects P2O5
Cool Soils Cool soils may induce phosphorus deficiency With cool soils you have slower root growth and development Less opportunity for roots to come in contact with the phosphorus they need at this time Limiting phosphorus in cool seasons exacerbates the ability for cool season vegetables to grow.
Cation Inhibition Calcium and zinc cations (and others) have an affinity for PO4, phosphate anion. They form calcium and zinc phosphate precipitates which are now hard to resolubilize for root uptake. But this also helps reduce leaching of PO4 from the soil solution.
Plant Phosphorus Utilization Forms nucleic acids (DNA and RNA) Used in the making of the chemical energy molecules of ATP and ADP. Through this transfer of chemical energy it is utilized in new growth and reproduction. Note that dry leaf analysis of P2O5 in young leaves is always higher than that found in older leaves.
Symptoms of Phosphorus Deficiency Slow growth, stunted plants Purplish coloration on foliage of some plants (older leaves first) Dark green coloration Delayed maturity Poor fruit or seed development
Not So Obvious Symptoms of Phosphorus Deficiency Poor root development Reduced production Sizing reduction Fruit set reduction
Phosphate vs. Phosphite or Phosphoric Acid vs. Phosphorous Acid One is the source for a fertilizer, the other is a source for a fertilizer and a fungicide. PO4 vs. PO3. PO3 will (?) oxidize eventually to PO4 Know the difference. There is still quite a bit of confusion regarding these source products
Four Recent Trials with Phosphates in Peppers and Strawberries. Phosphates generally placed in addition to the grower s standard practices which may include pre-plant and in-season phosphate applications. All crops grown on tape, which allows for precise in season placement of phosphate.
Early Spring 2010 Peppers Pre-Plant poly phosphate applied as band under seedline on 4/27/10 Pre-Plant Phosphorus (Olsen Method) 41 ppm Treat 1 untreated Treat 2 100 lb/ac P2O5 as 10-34-0 Treat 3 55 lb/ac P2O5 as Proprietary Treat 4-30 lb/ac P2O5 as Proprietary Planted 5/5/10
Chart 1: 2010 Spring - Summer Bell Pepper Phosphate Study - Camarillo, CA. - Total Yield per Plant 2.5 2.0 Pounds of Fruit 1.5 1.0 0.5 0.0 Lbs./Plant UTC 1.6 Reduced Propietery 2 1.6 Reduced Propietery 1 1.8 Grower Standard 2.3 b b ab a
Post Treat Soil P2O5 Levels Treat 1 30 ppm Treat 2 31 ppm Treat 3 34 ppm Treat 4 27 ppm
Late Spring 2010 Peppers Pre-Plant poly phosphate applied as band under seedline on 6/17/10 Pre-Plant Phosphorus (Olsen Method) 44 ppm Treat 1 125 lb/ac P2O5 as 10-34-0 Treat 2 100 lb/ac P2O5 as 10-34-0 Planted 6/20/10
Chart 2: 2010 Late Spring - Summer Bell Pepper Phosphate Study - Camarillo, CA. - Total Yield per Plant 2.5 2.0 Pounds of Fruit 1.5 1.0 0.5 0.0 Lbs./Plant 100 lb P2O5 2.1 125 lb P2O5 2.2
Post Treat Soil and Leaf P2O5 Treat 1 40 ppm Treat 2 49 ppm Leaf Treat 1 -.32% Leaf Treat 2 -.35% Levels
2008-09 Strawberries Planted 10/2/08 All Received Pre-Plant and in-season Phosphate 500 lb/ac 18-8-13 slow release Approximately 20 gal/ac Phosphoric acid in season (150 lb P2O5) in tape Experimental Treatment received another 80 lb/ac of P2O5 in the tape and 40 lb/ac of P2O5 foliar as Proprietary Product
Plant Sizing at Nine Weeks after Planting Grower Standard Additional Phosphate
5000.0 4500.0 Chart 6: Proprietery 2008-09 Strawberry Nutrient Study - Camarillo, CA. - Cumulative Marketable Production by Pick Day Trays per Acre (10 lb. equivalent) 4000.0 3500.0 3000.0 2500.0 2000.0 1500.0 1000.0 500.0 0.0 12/8/08 12/11/08 12/16/08 12/20/08 12/22/08 12/24/08 12/27/08 12/30/08 1/3/09 1/7/09 1/12/09 1/16/09 1/19/09 1/21/09 1/24/09 1/28/09 2/3/09 2/6/09 2/10/09 2/16/09 2/20/09 2/24/09 2/27/09 3/2/09 3/5/09 3/9/09 3/12/09 3/16/09 3/21/09 3/25/09 3/28/09 4/1/09 4/6/09 4/10/09 Pick Day Grower Standard Proprietery
Chart 6: Proprietery 2008-09 Strawberry Nutrient Study - Camarillo, CA. - Early Cumulative Marketable Production by Pick Day Trays per Acre (10 lb. equivalent) 1200.0 1000.0 800.0 600.0 400.0 200.0 155 flats ahead 0.0 12/8/08 12/11/08 12/16/08 12/20/08 12/22/08 12/24/08 12/27/08 12/30/08 1/3/09 1/7/09 1/12/09 1/16/09 1/19/09 1/21/09 1/24/09 1/28/09 2/3/09 2/6/09 2/10/09 2/16/09 2/20/09 2/24/09 2/27/09 Pick Day Grower Standard Proprietery
Chart 6: Proprietery 2008-09 Strawberry Nutrient Study - Camarillo, CA. - Late Cumulative Marketable Production by Pick Day 5000.0 4500.0 57 flats behind Trays per Acre (10 lb. equivalent) 4000.0 3500.0 3000.0 2500.0 2000.0 1500.0 1000.0 500.0 0.0 3/2/09 3/5/09 3/9/09 3/12/09 3/16/09 3/21/09 3/25/09 3/28/09 4/1/09 4/6/09 4/10/09 Pick Day Grower Standard Proprietery
Conclusions Additional Early Season applications of P2O5 did help increase early season production As soils warmed and crop finished out the end season differential was not as great Early season production does return the grower a better price per flat.
Planted 10/3/09 2009-10 Strawberries All Received Pre-Plant and in-season Phosphate 500 lb/ac 18-8-13 slow release Approximately 20 gal/ac Phosphoric acid in season (150 lb P2O5) in tape Experimental Treatment received another 45 lb/ac of P2O5 in the tape as 3-18-18 (ortho phosphate) over five applications Also Proprietary product run alone and in combination with 3-18-18
Plant Sizing at Nine Weeks Grower Standard Product A 3-18-18/Product A 3-18-18
6000.0 Chart 8: Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010 - Cumulative Marketable Production by Pick Day 5000.0 Trays per Acre (10 lb. equivalent) 4000.0 3000.0 2000.0 1000.0 0.0 12/14/2009 12/17/2009 12/22/2009 12/27/09 12/30/09 1/4/10 1/8/2010 1/11/2010 1/15/2010 1/18/2010 1/22/2010 1/25/2010 1/29/2010 2/1/2010 2/4/2010 2/8/2010 2/12/2010 2/16/2010 2/22/2010 2/25/2010 3/1/2010 3/4/2010 3/8/2010 3/11/2010 3/15/2010 3/18/2010 3/22/2010 3/26/2010 3/29/2010 4/2/2010 4/5/2010 4/9/2010 1 2 3 4 5 6 7 8 9 10 11 12 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Pick Day Product A/3-18-18 Product A Alone Grower Standard 3-18-18 Alone
800.0 Chart 8a: Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010 - Cumulative Marketable Production by Pick Day 700.0 Trays per Acre (10 lb. equivalent) 600.0 500.0 400.0 300.0 200.0 100.0 0.0 12/14/2009 12/17/2009 12/22/2009 12/27/09 12/30/09 1/4/10 1/8/2010 1/11/2010 1/15/2010 1/18/2010 1/22/2010 1/25/2010 1/29/2010 1 2 3 4 5 6 7 8 9 10 11 12 12 Pick Day Product A/3-18-18 Product A Alone Grower Standard 3-18-18 Alone
6000.0 Chart 8a: Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010 - Cumulative Marketable Production by Pick Day 5000.0 Trays per Acre (10 lb. equivalent) 4000.0 3000.0 2000.0 1000.0 0.0 2/1/2010 2/4/2010 2/8/2010 2/12/2010 2/16/2010 2/22/2010 2/25/2010 3/1/2010 3/4/2010 3/8/2010 3/11/2010 3/15/2010 3/18/2010 3/22/2010 3/26/2010 3/29/2010 4/2/2010 4/5/2010 4/9/2010 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Pick Day Product A/3-18-18 Product A Alone Grower Standard 3-18-18 Alone
Dollars per Acre - Gross (does not include cost of program $2,500.00 $2,000.00 $1,500.00 $1,000.00 $500.00 $0.00 -$500.00 -$1,000.00 -$1,500.00 -$2,000.00 -$2,500.00 Chart 9:Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010-Cumulative Differential from Grower Standard Return 12/14/2009 12/17/2009 12/22/2009 12/27/09 12/30/09 1/4/10 1/8/2010 1/11/2010 1/15/2010 1/18/2010 1/22/2010 1/25/2010 1/29/2010 2/1/2010 2/4/2010 2/8/2010 2/12/2010 2/16/2010 2/22/2010 2/25/2010 3/1/2010 3/4/2010 3/8/2010 3/11/2010 3/15/2010 3/18/2010 3/22/2010 3/26/2010 3/29/2010 4/2/2010 4/5/2010 4/9/2010 Pick Day Product A/3-18-18 Product A Alone 3-18-18 Alone
Conclusions Additional Early Season applications of P2O5 did help increase early season production Spring of 2010 was cooler than previous spring. With phosphate source removed in February, reduction in production was observed.
General Conclusions General production increases of 5-10% for coastal vegetables and strawberries when additional phosphate added to the growers standard programs in the fall, winter and early spring. These have occurred on soils that are not generally P2O5 deficient. 40-100 ppm P2O5 soils Similar results not observed in the summer time. No surprise that we are seeing a response on colder soils It is a surprise that what the grower s thought was sufficient supplies of phosphorus was not so.
Thank You!