Potassium Nutrition in the Northern Great Plains Outline

Potassium Nutrition in the Northern Great Plains

Outline: Potassium (K) Nutrition in the Northern Great Plains • • Role of K in crop production Soil K and soil test levels Crop uptake of K K deficiencies Crop responses to K Chloride (Cl) response Fertilizer K Photo courtesy of Lyle Cowell, SWP

What Is the Role of K in Plants? • K activates enzyme reactions • K controls water uptake and transpiration • K influences energy production in photosynthesis and respiration • K supports photosynthate transport • K fosters nitrate-nitrogen (N) uptake and protein synthesis • K is required for starch synthesis in seeds

Soil K Unavailable (90 to 98%) K K Soil Minerals (feldspar, mica) K K+ K+ Soil Water K+ K+ Readily available (0. 1 to 2%) K+ K+ Soil Colloid Trapped K Soil Colloid K+ K+ Slowly available (1 to 10%)

Soil Testing Methods for K • Most soil tests for K are based on either an ammonium acetate extraction or a similar extraction • In some regions with low CEC soils, K rates are often based on the ratio of K relative to other bases, such as Ca and Mg • Ion exchange membranes which measure the soil supply rate of K

Median Ammonium Acetate Equivalent Soil Test K Levels, 2005

Median Ammonium Acetate Equivalent Soil Test K Levels, 2005 AB SK 201 MB 254 207 MT 259 ND 265 North American-wide 154 ppm 2005

K Deficient Areas on Canadian Prairies May be deficient in K May need K for irrigated crops

Potassium Soil Test Rating and Recommendations - Soil test recommendations vary among labs. - Most labs use a set of regional crop response data to develop fertilizer recommendations based on a K soil test. An example: Wheat K 2 O recommendations using band application (Agvise Labs) Yield bu/A Soil test K, ppm 0 -40 41 -80 81 -120 121 -160 161 -200 201 -250 251 -750 +750 Fertilizer K recommendation, lb K 2 O/A 30 35 30 20 10 10 0 40 50 40 30 15 10 10 10 0 50 65 50 35 20 10 10 10 0 60 75 60 40 25 10 10 10 0 70 90 70 50 30 10 10 10 0

What Are the K Requirements of Crops throughout the Season? Photo courtesy of Lyle Cowell

K Uptake of Wheat During the Growing Season Jacobsen et al. , 1992 (graphic from Korb et al. , 2002)

Crop Uptake of K K uptake in Crop Yield/A total crop, lb K 2 O/A Wheat 40 bu 80 (19)* Canola 35 bu 89 (20) Peas 50 bu 150 (39) Barley silage 4. 5 tons 132 Alfalfa 3 tons 180 *K removed in grain in parenthesis.

Potassium Deficiency Symptoms in Barley grain yield, bu/A 58 60 49 50 38 40 30 20 11 10 0 0 60 120 240 K 2 O rate in lb/A

Potassium Budget in the Northern Great Plains Region, 2000 -2001 State or Province Crop Removal Fertilizer Applied Recoverable Manure (R) (F) (M) Balance F-R F+M-R ----------- K 2 O, million lb ----------Alberta 607 128 136 -479 -343 Saskatchewan 640 59 43 -581 -538 Manitoba 332 92 45 -240 -195 Montana 352 42 9 -310 -301 North Dakota 609 52 13 -557 -544

K Deficiency Symptoms

K Deficiency Symptoms

Plant Tissue K Guidelines for Crops … An Example % K in plant tissue Crop type -- stage Deficient Low Sufficient High Wheat – tillering <1. 2 1. 3 – 1. 5 1. 6 – 3. 0 3. 1 – 9. 9 Wheat – boot <1. 4 1. 5 – 1. 9 2. 0 – 2. 4 2. 5 – 3. 5 Wheat – heading <1. 2 1. 3 – 1. 5 1. 6 – 3. 0 3. 1 – 9. 9 Alfalfa – top 6 in. <1. 7 1. 8 – 2. 4 2. 5 – 3. 8 3. 9 – 4. 7 Agvise Labs

Crop Responses to K • While many northern Great Plains soils have abundant K, the region also has areas with very low soil K • It is not uncommon to find areas of Saskatchewan and Alberta with soils testing 30 to 50 ppm K/A • Crops respond to K application in these low K soils

Barley Response to Soil K Levels and Fertilizer K 2 O % Grain Yield Increase 80 Soil K 25 -50 ppm/A 70 60 50 40 Soil K 50 -75 ppm/A 30 Soil K 75 -100 ppm/A 20 10 0 0 12 24 Added K, lbs K 2 O/A added to seed row N and P added to soil test recommendation D. Walker, Lacombe, AB

Barley, Wheat, and Canola Response to K 70 Grain yield, bu/A 60 Barley 50 40 72 ppm K/A 33 ppm K/A 30 20 Canola 50 ppm K/A Wheat 36 ppm K/A 30 ppm K/A 10 0 0 100 200 400 Added K (lb K 2 O/A Broadcast + Incorp) N and P added to soil test recommendation Henry and Halstead, 1968

K Benefits Crop Growth and Yield Longevity of Alfalfa Stands • K increases carbohydrate in the crown roots of alfalfa during fall growth to increase - Winter hardiness - Early spring re-growth

K Helps Reduce Winterkill in Alfalfa Manitoba - Soil K 116 ppm/A (0 to 6 in. ) Stand density, % 100 No K 100 lb K 2 O/yr 80 60 40 20 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Plant counts in May as % of those the previous September

Crop Response on High K Soils • Yield increases often occur from potash applied on soils not deficient in K. Why? • K responses as a result of: - Cold soils in the spring (slow root growth and nutrient uptake) - Dry soils (droughty conditions reduce K diffusion) - Field (landscape) variability - Cl ion (Cl-) response

Barley Response to Starter K and Seeding Date 7 bu Barley Yield (bu/A) 60 50 6 bu 40 3 bu Check 20 K 2 O 30 20 10 0 April 6 Soil K levels - High May 6 June 3 Dubbs, Montana State Univ.

Crop Response to Added K in High K Soils in Montana (264 Sites) Frequency of response, % 0 20 Winter Wheat 97 Expts. Spring Wheat 33 Expts Feed Barley 48 Expts. 40 60 5. 5 bu/A 4. 8 bu/A 3. 9 bu/A 9. 2 bu/A Malt Barley (irr. ) 10 Expts. Alfalfa Corn Silage Potatoes (irr. ) 36 Expts. 22 Expts. 18 Expts. 80 0. 35 t/A 2. 8 t/A 25 cwt/A Each crop represents 2 to 8 cropping years Soils testing > 600 ppm (1967 -1979) Skogley & Haby 1981

Crop Response to Added K in Alberta (548 sites) Exch. K Total ppm/A 0 - 50 51 - 100 101 - 150 151 - 200 201 - 300 301 - 400 > 400 28 Responsive sites, % 37 70 132 73 115 55 100 52 99 46 37 43 21 1. 9 Average Resp. , cwt/A 6. 1 4. 8 2. 5 2. 4 2. 7 2. 4 Barley, oats, and rape – 1968 -74 Lopetinsky 1977

Frequency (%) Frequency Distribution of Soil K on a 220 x 220 ft. Grid at Mundare, AB 35 30 25 20 15 10 5 0 Mean = 135 ppm Mode = 108 ppm 59 -101 101143 143185 185227 Soil K (ppm) Penny et al. , 1996 227269 269311

Chloride---An Essential Plant Nutrient • The deficiency of Cl in the soil can account for crop responses to KCl application. • Earliest report of Cl crop response. . . table salt (Na. Cl) in mid 1800 s • Recognized as an essential micronutrient since the 1950 s • Research in the late 1970 s revealed insufficient levels in many areas

Crop Responses to Chloride • Chloride has been shown to have an effect on: – Root rot and foliar diseases in cereal crops – Seed weight at harvest, especially barley, by extending the grain filling period – Reducing physiological leaf spot in cereal crops on fields where soil Cl is less than 10 lb/A (24 in. depth) – Increasing crop yields

Physiological Leaf Spot on Kestrel Winter Wheat No Chloride

Chloride May Improve Crop Yields • ~ 200 university trials in KS, MN, MT, ND, SD, MB, and SK have evaluated Cl response in wheat and barley – Included non-responsive and high Cl sites • Significant yield response in 48% of trials • Average yield response of 5 bu/A

Yield Boost from Chloride Depends on Wheat Variety Yield response, bu/A 12 1996 10 1997 1998 8 6 4 2 0 -2 -4 -6 Barrie Cora Grandin Karma Kyle

Fertilizer K Management

Once in the soil, all fertilizer sources are the same form as found in the soil (K+). This is the form taken up by plants. + K KCl K 2 SO 4

What Happens to Fertilizer K in the Soil? • Absorbed by crop in year 1: – 20 to 60% of applied K – Highest recovery on low K soils • Slowly available K (future years): – Bulk of remaining K in most soil types – Future supply of K Available K Slowly Available K Unavailable K

Fertilizer K Sources Source Analysis Potassium chloride, KCl 0 -0 -60 (62) Potassium sulfate, K 2 SO 4 0 -0 -50 - 17 Potassium nitrate, KNO 3 13 -0 -44 Potassium-magnesium sulfate, K 2 SO 4. 2 Mg. SO 4 0 -0 -22 -22 -11 Potassium thiosulfate, K 2 S 2 O 3 0 -0 -25 -17

Fertilizer K Placement

Grain Yield Increase (bu/A) Barley Response to KCl Placement and Rate 30 Seed row 25 Side band 20 Broadcast 15 10 5 0 0 15 30 60 90 120 150 180 240 lb K 2 O/A N and P added to soil test recommendation SIP Soil Fertility Rpt, 1968

Safe Rates of Seed Row K application (Saskatchewan) • Seed row application of K 2 O should not exceed (1 in. spread, 6 to 7 in. rows): – Cereals – 50 lb K 2 O/A – Canola – 20 lb K 2 O/A – Dry pea – 15 lb K 2 O/A • Combined P 2 O 5 and K 2 O in the seed row should also not exceed the recommended safe rates for K 2 O alone Source: Saskatchewan Agriculture and Food

• Split-root experiment • Percent of the total root system on the side with K was the same as that on the side without K • Effects of K on root growth may not be localized as is found with P Proportion of roots observed in K solution (%) Potassium Does Not Cause Roots to Proliferate 100 Corn 17 days old 80 60 40 20 0 0 20 40 60 80 Proportion of roots expected for no K effect (%) Classen and Barber, 1977 100

Be Sure and Use Soil Testing to Monitor Soil K Supplies

Summary— K Nutrition in the Northern Great Plains • K nutrition is critical to crop production • Most northern Great Plains soils are high in K, allowing for a net removal of soil K each year • Crops take up as much K as N during growth, with only a small proportion removed in grain • Where deficient, crop response to K is greatest for barley, followed by wheat and canola • Crop responses to muriate of potash (KCl) can be a Cl response

International Plant Nutrition Institute 655 Engineering Drive, Suite 110 Norcross, GA 30092 -2604 Phone: 770 -447 -0335; Fax: 770 -448 -0439 www. ipni. net Reference #06111