Phosphorus Fertilization in Sugar Beets

Introduction In-furrow P applications at planting and broadcast P applications have generally given some level of sugar beet root yield response in southern Alberta soils that are moderately P deficient.

Alberta phosphorus trials ‘Root yield’ responses – tons/acre Treatment Yield gain 2003 Check (tons/acre) (32.2) Broadcast P +2.5 LSD (.05) 1.8 Broadcast P = 60 lbs P2O5/ac, Moderately P deficient soil

Alberta phosphorus trials ‘Root yield’ responses – tons/acre Treatment Yield gain 2004 2005 2007 Check (tons/acre) (21.3) (27.3) (27.8) In-furrow P +2.9 +3.0 +0.7 Broadcast P +4.2 +5.1 +2.4 Bcast + In-furrow P +5.3 +6.2 +2.6 LSD (.05) 2.4 1.5 NS Broadcast granular P = 60 lbs P2O5/ac, In-furrow P = 12 lbs P2O5/ac (3 US gallons/ac 10-34-0) Moderately P deficient soils

2013 Phosphorus Trials There was interest in evaluating whether banding P directly under the row before planting could increase the efficiency of P uptake.

JD Flexi-planter modified for banding P fertilizer under the row

Elmer’s Strip Tiller for banding P fertilizer under the row

Lime Treatments before incorporation

2013 Alberta phosphorus trials ‘Root yield’ responses – tons/acre Treatment Yield gain 2013 – test A 2013 – test B Check (tons/acre) (32.0) (30.9) Broadcast P +1.5 +2.2 P under the row +0.6 +4.0 PCC – 2.2 tons/ac +1.0 +1.8 PCC – 4.4 tons/ac +2.3 LSD (.05) 0.9 1.8 Broadcast & under the row P = 50 lbs P2O5/ac Moderately P deficient soils

2014 Phosphorus Trials Under the row P treatments were expanded in 2014. Sites were not as P deficient as in 2013. Trials in 2014 had some of the same trends as in 2013, but differences were not statistically significant.

2014 Alberta phosphorus trials ‘Root yield’ responses – tons/acre Treatment Yield gain 2014 – test A 2014 – test B Check (tons/acre) (35.7) (32.2) Broadcast P +1.5 +1.3 P ‘deep’ under row +0.1 +0.6 P ‘shallow’ under row +0.7 +1.7 PCC – 2.75 tons/ac PCC – 5.5 tons/ac +1.0 LSD (.05) NS Broadcast & under the row P = 50 lbs P2O5/ac P under the row is an average of Zone tillage and JD 71 Flexi-planter treatments

2015 & 2016 Phosphorus Trials An opportunity presented itself to conduct trials on soil that was ‘very’ deficient in P. Alfalfa breaking in both years. (No P fertilizer for 7 & 8 years) Soil P levels were less than 10 lbs/acre (<5ppm) in both years.

Treatments 2015 – 2 tests (18 total treatments) 2016 - 1 test (12 treatments) Main treatments I will focus on: Untreated check Broadcast granular P (50 lbs P2O5/ac) as 0-45-0 In-furrow P (8 lbs P2O5/ac) as 10-34-0 (2 US gal/ac) In-furrow P (2 US gal/ac) + granular broadcast P (50 lbs P2O5/ac) Liquid P under the row at 2 depths (50 lbs P2O5/ac as 10-34-0) Broadcast PCC (2.75 and 5.5 tons/ac) Other liquid in-furrow treatments responded the same as 10-34-0

2015 Alberta phosphorus trial A ‘Vigour’ responses: 1-9 scale Treatment June 26 July 20 Oct 1 Check treatment 5.8 4.4 Broadcast P 7.3 8.0 7.0 In-furrow P 7.7 6.8 Broadcast + In-furrow P 7.9 LSD (.01) 0.8 1.2 1.3 Broadcast P = 50 lbs P2O5/ac In-furrow P = 8 lbs P2O5/ac

2015 Alberta phosphorus trial A ‘Root yield’ responses – tons/acre Treatment Yield gain 2015 – test A Check (tons/acre) (23.9) Broadcast P +8.7 In-furrow P +2.6 Broadcast + In-furrow P LSD (.05) 2.6 LSD (.01) 3.5 Broadcast P = 50 lbs P2O5/ac In-furrow P = 8 lbs P2O5/ac

2015 Alberta phosphorus trial B ‘Root yield’ responses – tons/acre Treatment Yield gain 2015 – test B Check (tons/acre) (21.4) Broadcast P +9.6 P ‘deep’ under the row (4”) +10.3 P ‘shallow’ under the row (2”) +10.7 PCC – 2.75 tpa +8.3 PCC – 5.5 tpa +10.4 LSD (.01) 3.0 Broadcast & under the row P = 50 lbs P2O5/ac

2016 Alberta phosphorus trial ‘Root yield’ responses – tons/acre Treatment Yield gain (tons/ac) Check (16.0) Broadcast P +12.0 In-furrow P +5.4 Broadcast + In-furrow P +12.7 LSD (.01) 3.6 Broadcast P = 50 lbs P2O5/ac In-furrow P = 8 lbs P2O5/ac

2016 Alberta phosphorus trial ‘Root yield’ responses – tons/acre Treatment Yield gain (tons/ac) Check (16.0) Broadcast P +12.0 P ‘deep’ under the row (4”) +12.5 P ‘shallow’ under the row (2”) +12.8 PCC – 2.75 tpa +11.7 PCC – 5.5 tpa +13.6 LSD (.01) 3.6 Broadcast & under the row P = 50 lbs P2O5/ac

2016 Alberta phosphorus trial ‘Extractable Sugar per Ton’ responses Treatment EST gain (lb/ton) Check (330.8) Broadcast P +18.4 In-furrow P +6.4 Broadcast + In-furrow P +14.2 LSD (.01) 11.6 Broadcast P = 50 lbs P2O5/ac In-furrow P = 8 lbs P2O5/ac

2016 Alberta phosphorus trial ‘Extractable Sugar per Ton’ responses Treatment EST gain (lb/ton) Check (330.8) Broadcast P +18.4 P ‘deep’ under the row +14.8 P ‘shallow’ under the row +10.0 PCC – 2.75 tpa +11.8 PCC – 5.5 tpa +20.8 LSD (.01) 11.6 Broadcast and under the row P = 50 lbs P2O5/ac

Check treatment in July 2016

In-furrow P (8 lbs P2O5/ac) in July 2016

Broadcast P (50 lbs P2O5/ac) in July 2016

5.5 tons/ac PCC in July 2016

Banded P (50 lbs P2O5/ac) in late August 2016

Soil Phosphorus Treatment 2015 2016 Soil P before the trial started (lbs/ac) 2016 Soil P before the trial started <10 Check (after the trial) 10 Broadcast P (after the trial) 12 2.75 tons/ac PCC (after the trial) 14 5.5 tons/ac PCC (after the trial) 22 20 Broadcast P = 50 lbs P2O5/ac

Conclusions for ‘very deficient’ P soils (2015 and 2016) There was a significant increase in early season vigour with broadcast P, P under the row, in-furrow P and PCC, but vigour for in-furrow treatments did not carry through to harvest. In-furrow P increased yield by an average of 4.1 tons/ac, but in-furrow applications did not provide enough phosphorus to maximize production on soils very deficient in P. A combination of in-furrow and broadcast P was not better than broadcast P alone. (but these trials were not conducted under cool early season conditions) Different in-furrow fertilizer products (10-34-0, Aventine Complete and PowerStart – data not shown) performed the same.

Conclusions for ‘very deficient’ P soils (2015 and 2016) There were no significant differences in root yield or quality between broadcast P and P banded under the row. Broadcast and banded P applications increased yield by an average of 11.3 tons/ac. Spring PCC applications of 2.75 and 5.5 tons/ac increased root yield by and average of 10.0 and 12.0 tons/ac, respectively. PCC applications of 5.5 tons/ac had equivalent or better P supplying power as 50 lbs P2O5/ac fertilizer treatments. PCC applications of 5.5 tons/ac raised the available soil P level.

Questions?