Potassium Management for Irrigated Russet Burbank Potato Production in Manitoba

Transcription

1 Potassium Management for Irrigated Russet Burbank Potato Production in Manitoba Funding: ARDI 50% Keystone Vegetable Producers 16.6% Simplot Canada 16.6% McCain Foods 16.7% In Kind Delta Ag Services Beaver Creek Farms WF Farms Progress: Second of three years Principal Investigators: Blair Geisel, Darin Gibson and Donovan Fehr, Gaia Consulting Ltd. Introduction: In the past 6 years, fertility studies conducted by Keystone Potato Producers, McCain and Simplot have concentrated mainly on nitrogen and phosphorus. In 2010 the focus on nutrient studies shifted to potassium for two reasons. Since 2004, potato yields have increased by 30% and the price of potash (potassium) has increased by over 400%. Because of these changes, potassium management must be fine-tuned to optimize yield, quality and profit. Agvise Laboratories and MAFRI indicate that a response in potato yield to potassium fertilizer would likely occur in soils with less than 150 and 200 ppm K to 6 inches respectively. If these recommendations are no longer valid then producers may not be maximizing net return. Under-application of potassium might limit yields whereas over application will increase costs. Either situation will reduce net profit. In 2010 the effect of different rates and application timings of potassium fertilizer on irrigated Russet Burbank potatoes was studied at two sites. In 2010, there was no difference in marketable or total yield between treatments at both locations. The residual potassium levels of 144 and 263 ppm were sufficient to maximize yield. At both locations, the concentration of potassium in the petiole tended to increase with increasing rates of potassium fertilizer. Application timing had no effect on the concentration of potassium in the petiole. The application of additional potassium improved fry colour. Increasing rates of potassium decreased specific gravity at one of two sites (Melbourne). There were no differences in yield 1

2 or quality between the application of potassium as KMAG or KCL. There were no differences in yield or quality between applying all potassium at plant or in split applications. In 2011, the concentration of potassium in the petiole increased with increasing rates of applied potassium fertilizer. Application timing had no effect on the concentration of potassium in the petiole. The addition of potassium fertilizer increased yield at the Beaver site where soil residual concentrations were deficient (83 ppm). Two hundred (200) lbs K 2 O /ac at plant or 300 lbs K 2 O /ac in split applications was required to maximize yield. At both sites, potassium fertilizer rates greater than 100 lbs K 2 O /ac reduced specific gravity when compared to the check. There was no difference in yield or quality between the application of potassium as KMAG or KCL. The above results are consistent with the conclusions of other studies conducted in the province. A 6 station-year study (3 years times 2 sites) conducted by AAFC and CMCDC reported that at one site (Douglas), increases in total and marketable yield and decreases in percent solids were associated with KCl application. At this site, residual K ranged from 115 to 189 ppm in six inches of soil. Effects on yield and gravity were most pronounced at the 150 to 300 kg K 2 O/ha (134 to 268 lbs K 2 O /acre) application rates. The application of KCl at the Carberry site had no effect on total or marketable yield or percent solids. At this site, residual K concentrations in the soil varied from 175 to 380 ppm in six inches (280 to 760 kg K/ha). Objectives: 1. Determine the effect of potassium rate and application timing on Russet Burbank yield and quality. 2. Determine critical soil and tissue levels at which a response to potassium can be expected. Procedure: 3. Determine the effect of potassium source as well as the addition of sulfur and magnesium (present in KMAG or potassium magnesium sulfate) on Russet Burbank yield and quality. Plot size: 4 rows by 12 m (Assessments conducted on 2 centre rows) Trial design: RCB 4 replicates Plot locations: Bagot and Beaver, Manitoba Crop: Potatoes Variety: Russet Burbank Row spacing: 1 metre Site Description: Table 1 2

3 Planting Date: Bagot May , Beaver May Harvest Date: Bagot September Beaver September s: Table 2 Table 1 Site description Year Location Soil type NO 3 -N (0-24") (lbs/ac) Residual Soil Nutrients P 2 O 5 (ppm) K 2 O (ppm) Mg (ppm) S (0-24") (ppm) Ph CEC (meq) CCE % 2010 Melbourne Hochfeld - fine sandy loam MacDonald Stockton fine sandy loam Bagot Willowcrest - loamy fine sand Beaver Willowcrest/Almasippi - sandy loam Table 2 List of fertilizer treatments for the Bagot and Beaver sites product applied (lbs/acre) Urea MAP KCl (NH 4 ) 2 SO 4 KMAG NO 3 P 2 O 5 K 2 O SO 4 Mg 1 Zero K lb at Plant lb at Plant lb at Plant lb at Plant lb split lb split lb split lb split KMAG/ lb split Nutrients Provided (lbs/acre) Fertilizer Application Notes: At both sites, 96 lbs/ac MAP and 139 lbs/ac Urea were applied in a sideband with the planter. At both sites, treatment 10 received 14 lbs/ac Urea broadcast at plant. At both sites, all Ammonium Sulfate (NH4)2SO4 was broadcast at plant At both sites, treatments 2-5 received all potash broadcasted at plant. At both sites, treatments 6-10 received 50% potash or KMAG broadcast at plant, 50% at hilling 35 to 38 days after emergence. At both sites, 95 lbs/ac Urea was broadcast at hilling 35 to 38 days after emergence. At the Beaver site, 115 lbs/ac of Agrotain treated Urea was broadcast on July 21. At the Bagot site, 55 lbs N/ac was fertigated on 3 dates in July.

4 Results Petiole Concentration of Potassium (Table 3 and Table 4) Petiole samples were collected 70 and 72 days after emergence (DAE) at the Bagot and Beaver sites respectively. The optimum (sufficient) concentration of potassium in a Russet Burbank petiole changes as the plant ages: 0-40 days after emergence % days after emergence % days after emergence % Concentrations of potassium in the petiole were sufficient for all treatments with the exception of the untreated checks at both sites and treatments 2 and 6 (100 lb K 2 O /acre rates) at the Beaver site. Residual K concentrations in the soil were higher at the Bagot than the Beaver site, which is reflected in higher petiole K concentrations at Bagot. At both locations, the concentration of potassium in the petiole tended to increase with increasing rates of potassium fertilizer. Application timing had no effect on the concentration of potassium in the petiole with the exception of the 400 lb treatments (5 and 9) at Beaver. Applying 300 lb/acre KMAG (treatment 10) increased the concentration of potassium in the petiole, however, the concentration was the same (p = 0.05) as the 300 lb/acre split application of KCl (#8). Table 3 Effect of fertilizer treatment on petiole potassium concentration at Bagot on August 15 th, 70 DAE Petiole Conc. % Potassium 1 Zero K 6.2 e lb at Plant 7.8 cde lb at Plant 9.3 a-d lb at Plant 10.1 ab lb at Plant 10.4 a lb split 7.7 de lb split 8.4 bcd lb split 9.4 a-d lb split 10.1 ab 10 KMAG/ lb split 9.7 abc LSD (P=.05) 2.0 CV 15.3 Prob(F)

5 Table 4 Effect of fertilizer treatment on petiole potassium concentration at Beaver on August 15 th, 72 DAE Petiole Conc. % Potassium 1 Zero K 5.5 c lb at Plant 5.9 c lb at Plant 7.6 b lb at Plant 7.8 b lb at Plant 7.9 b lb split 5.7 c lb split 7.4 b lb split 8.1 ab lb split 9.2 a 10 KMAG/ lb split 7.5 b LSD (P=.05) 1.2 CV 11.5 Prob(F) Results Yield (Table 5 and Table 6) There was no difference in marketable or total yield between treatments at Bagot. The residual potassium concentration of 174 ppm in the soil was sufficient to maximize yield. At the Beaver site, there was a yield response to applied potassium. The residual potassium concentration of 83 ppm in the soil was insufficient to maximize yield. At Beaver 200 lbs K 2 O /ac at plant (treatment 3) or 300 lbs K 2 O /ac split (treatment 8) was required to maximize marketable yield. 5

6 Table 5 Effect of potassium rate and timing on yield at Bagot Yield (cwt) lbs K Undersize Marketab Total Bonus % Removed 1 Zero K a a a 14.8 a lb at Plant a a a 19.0 a lb at Plant 72.0 a a a 28.3 a lb at Plant 87.8 a a a 20.3 a lb at Plant 83.7 a a a 23.2 a lb split 96.4 a a a 13.2 a lb split 79.1 a a a 19.3 a lb split 77.4 a a a 19.5 a lb split 77.3 a a a 18.0 a KMAG/ lb split 77.7 a a a 18.7 a LSD (P=.05) CV Prob(F) Table 6 Effect of potassium rate and timing on yield at Beaver Yield (cwt) lbs K Undersize Marketable Total Bonus % Removed 1 Zero K 71.1 a c d 21.1 a lb at Plant 77.7 a bc bcd 22.4 a lb at Plant 62.7 a ab bc 25.7 a lb at Plant 68.5 a a a 21.5 a lb at Plant 67.7 a ab ab 22.2 a lb split 70.7 a bc bcd 19.7 a lb split 55.9 a bc cd 25.0 a lb split 51.3 a a ab 25.9 a lb split 38.8 a a ab 31.3 a KMAG/ lb split 54.2 a ab bcd 28.4 a LSD (P=.05) CV Prob(F) Results Quality (Table 7 through Table 10) There were no differences in hollow heart, fry colour or sugar end defect between treatments. At plant or split applications of greater than 100 lbs K/ac (treatments 3-5 and 6-10) reduced specific gravity compared to the check (treatment 1). 6

7 Table 7 Effect of potassium rate and timing on tuber quality at Bagot. Specific Hollow Heart Hollow Heart Gravity % by # % by wt 1 Zero K a 4.3 a 9.4 a lb at Plant a 2.4 a 4.1 a lb at Plant bc 3.1 a 5.4 a lb at Plant bcd 4.4 a 7.4 a lb at Plant bcd 0.0 a 0.0 a lb split ab 2.4 a 3.9 a lb split bc 1.5 a 2.7 a lb split cd 4.3 a 7.4 a lb split d 1.1 a 3.8 a 10 KMAG/ lb split cd 0.0 a 0.0 a LSD (P=.05) CV Prob(F) Table 8 Effect of potassium rate and timing on tuber quality at Beaver. Specific Hollow Heart Hollow Heart Gravity % by # % by wt 1 Zero K a 6.2 a 11.4 a lb at Plant ab 3.8 a 8.8 a lb at Plant cd 0.0 a 0.0 a lb at Plant cd 0.0 a 0.0 a lb at Plant d 1.7 a 2.2 a lb split a 5.3 a 9.4 a lb split bc 7.1 a 12.9 a lb split cd 0.0 a 0.0 a lb split d 0.0 a 0.0 a 10 KMAG/ lb split cd 0.0 a 0.0 a LSD (P=.05) CV Prob(F)

8 Table 9 Effect of potassium rate and timing on French fry colour and sugar end defect at Bagot. 12-Oct 12-Jan 27-Mar Fry Colour Sugar End % Fry Colour Sugar End % Fry Colour Sugar End % 1 Zero K 0.12 a 5.5 a 0.13 a 17.5 a 0.05 a 12.5 a lb at Plant 0.08 a 0.0 a 0.03 b 5.0 bc 0.00 a 0.0 a lb at Plant 0.03 a 0.0 a 0.03 b 0.0 c 0.00 a 2.5 a lb at Plant 0.10 a 10.0 a 0.00 b 5.0 bc 0.08 a 5.0 a lb at Plant 0.08 a 2.5 a 0.00 b 13.1 ab 0.00 a 7.5 a lb split 0.10 a 10.0 a 0.03 b 5.0 bc 0.08 a 0.0 a lb split 0.05 a 2.5 a 0.03 b 0.0 c 0.00 a 0.0 a lb split 0.10 a 0.0 a 0.00 b 0.0 c 0.03 a 7.5 a lb split 0.08 a 12.5 a 0.00 b 5.0 bc 0.00 a 2.5 a 10 KMAG/ lb split 0.00 a 5.0 a 0.00 b 2.5 bc 0.03 a 5.0 a LSD (P=.05) CV Prob(F) Table 10 Effect of potassium rate and timing on French fry colour and sugar end defect at Beaver. 11-Oct 12-Jan 27-Mar Fry Colour Sugar End % Fry Colour Sugar End % Fry Colour Sugar End % 1 Zero K 0.03 a 10.0 a 0.10 a 12.5 bc 0.14 a 7.5 a lb at Plant 0.00 a 5.0 a 0.03 a 7.5 bc 0.05 a 0.0 a lb at Plant 0.05 a 5.0 a 0.03 a 10.0 bc 0.05 a 7.5 a lb at Plant 0.05 a 20.0 a 0.03 a 17.5 bc 0.00 a 15.0 a lb at Plant 0.00 a 7.5 a 0.05 a 7.5 bc 0.00 a 7.5 a lb split 0.03 a 10.0 a 0.05 a 10.0 bc 0.05 a 7.5 a lb split 0.03 a 2.5 a 0.00 a 7.5 bc 0.00 a 2.5 a lb split 0.00 a 2.5 a 0.00 a 5.0 c 0.05 a 5.0 a lb split 0.00 a 15.0 a 0.00 a 22.8 ab 0.02 a 20.0 a 10 KMAG/ lb split 0.05 a 22.5 a 0.05 a 35.0 a 0.00 a 17.5 a LSD (P=.05) CV Prob(F)

9 Conclusion: In 2011, the concentration of potassium in the petiole increased with increasing rates of applied potassium fertilizer. Application timing had no effect on the concentration of potassium in the petiole. The addition of potassium fertilizer increased yield at the Beaver site where soil residual concentrations were deficient (83 ppm). Two hundred (200) lbs K 2 O /ac at plant or 300 lbs K 2 O /ac in split applications was required to maximize yield. At both sites, potassium fertilizer rates greater than 100 lbs K 2 O /ac reduced specific gravity when compared to the check. There was no difference in yield or quality between the application of potassium as KMAG or KCL. 9