Potassium Nutrition in the Northern Great Plains
description
Transcript of Potassium Nutrition in the Northern Great Plains
Potassium Nutrition in the Northern Great Plains
Photo courtesy of Lyle Cowell, SWP
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
What Is the Role of Kin 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 WaterK+
K+K+
K+
K+ K+ K+K+
K+ K+ K+K+Trapped K
K
K K
KSoil Minerals
(feldspar, mica)
Soil Colloid
Soil Colloid
Soil Colloid
K
Unavailable (90 to 98%)
Slowly available (1 to 10%)
Readily available (0.1 to 2%)
Soil K
Soil Testing Methodsfor 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
2005
ND
SK MBAB
MT
207
259 265
201 254
North American-wide154 ppm
K Deficient Areas on Canadian Prairies
May be deficient in K
May need K for irrigated crops
Potassium Soil Test Ratingand Recommendations
Yield Soil test K, ppm
bu/A 0-40 41-80 81-120 121-160 161-200 201-250 251-750 +750
Fertilizer K recommendation, lb K2O/A
30 35 30 20 10 10 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
Wheat K2O recommendations using band application (Agvise Labs)
- 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:
What Are the K Requirements of Crops throughout the Season?
Photo courtesy of Lyle Cowell
K Uptake of Wheat Duringthe 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 K2O/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 DeficiencySymptoms in Barley
11
38
49
58
0 60 120 2400
10
20
30
40
50
60
Ba
rle
y g
rain
yie
ld, b
u/A
K2O rate in lb/A
Potassium Budget in the Northern Great Plains Region, 2000-2001
-544-5571352609North Dakota
-301-310942352Montana
-195-2404592332Manitoba
-538-5814359640Saskatchewan
-343-479136128607Alberta
--------------------- K2O, million lb ---------------------
F+M-RF-R(M)(F)(R)
BalanceRecoverable Manure
Fertilizer Applied
Crop Removal
State or Province
K Deficiency Symptoms
K Deficiency Symptoms
Plant Tissue K Guidelines for Crops … An Example
3.9 – 4.72.5 – 3.81.8 – 2.4<1.7Alfalfa – top 6 in.
3.1 – 9.91.6 – 3.01.3 – 1.5<1.2Wheat – heading
2.5 – 3.52.0 – 2.41.5 – 1.9<1.4Wheat – boot
3.1 – 9.91.6 – 3.01.3 – 1.5<1.2Wheat – tillering
HighSufficientLowDeficientCrop type -- stage
% K in plant tissue
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 K2O
N and P added to soil test recommendation D. Walker, Lacombe, AB
Soil K 50-75 ppm/A
Soil K 75-100 ppm/A
Soil K 25-50 ppm/A
0
10
20
30
40
50
60
70
80
0 12 24
Added K, lbs K2O/A added to seed row
% G
rain
Yie
ld In
cre
as
e
Barley, Wheat, and Canola Response to K
N and P added to soil test recommendation Henry and Halstead, 1968
72 ppm K/A
33 ppm K/A
30 ppm K/A
50 ppm K/A
36 ppm K/A
Canola
Wheat
Barley
0
10
20
30
40
50
60
70
0 100 200 400
Added K (lb K 2O/A Broadcast + Incorp)
Gra
in y
ield
, bu
/A
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
Manitoba - Soil K 116 ppm/A (0 to 6 in.)
100 lb K2O/yrNo K100
Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 70
20
40
60
80
Sta
nd
den
sity
, %
Plant counts in May as % of those the previous September
K Helps Reduce Winterkill in Alfalfa
Crop Response onHigh 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
Dubbs, Montana State Univ.Soil K levels - High
April 6 May 6 June 3
7 bu
6 bu
3 bu
0
10
20
30
40
50
60
Ba
rle
y Y
ield
(b
u/A
)
Check
20 K2O
Crop Response to Added K in High K Soils in Montana (264 Sites)
36 Expts.
48 Expts.
33 Expts
97 Expts.
0 20 40 60 80
Winter Wheat
Spring Wheat
Feed Barley
Malt Barley (irr.)
Alfalfa
Corn Silage
Potatoes (irr.)
10 Expts.
22 Expts.
18 Expts.
5.5 bu/A
4.8 bu/A
3.9 bu/A
9.2 bu/A
0.35 t/A
2.8 t/A
25 cwt/A
Frequency of response, %
Each crop represents 2 to 8 cropping yearsSoils testing > 600 ppm (1967-1979)
Skogley & Haby 1981
Barley, oats, and rape – 1968-74
Crop Response to Added K in Alberta (548 sites)
Exch. K Total Responsive Average ppm/A sites sites,% Resp., cwt/A
0 - 50 37 70 6.151 - 100 132 73 4.8
101 - 150 115 55 2.5151 - 200 100 52 2.4201 - 300 99 46 2.7301 - 400 37 43 2.4
> 400 28 21 1.9
Lopetinsky 1977
Frequency Distributionof Soil K on a 220 x 220 ft. Grid at Mundare, AB
Penny et al., 1996
Mean = 135 ppm
Mode = 108 ppm
0
5
10
15
20
25
30
35
Fre
qu
en
cy
(%
)
59-101 101-143
143-185
185-227
227-269
269-311
Soil K (ppm)
Chloride---An EssentialPlant Nutrient
• The deficiency of Cl in the soil can account for crop responses to KCl application.
• Earliest report of Cl crop response ... table salt (NaCl) in mid 1800s
• Recognized as an essential micronutrient since the 1950s
• Research in the late 1970s revealed insufficient levels in many areas
• 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
Crop Responses to Chloride
Physiological Leaf Spot on Kestrel Winter Wheat
No ChlorideNo Chloride ChlorideChloride
Chloride May ImproveCrop 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
-6
-4
-2
0
2
4
6
8
10
12
Yie
ld r
es
po
ns
e, b
u/A
Barrie Cora Grandin Karma Kyle
1996 1997 1998
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+
KClKCl KK22SOSO44
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 SlowlyAvailable K
Unavailable K
Fertilizer K Sources
Source Analysis
Potassium chloride, KCl 0-0-60 (62)
Potassium sulfate, K2SO4 0-0-50 - 17
Potassium nitrate, KNO3 13-0-44
Potassium-magnesium sulfate,
K2SO4.2MgSO4 0-0-22-22-11
Potassium thiosulfate, K2S2O3 0-0-25-17
Fertilizer K Placement
Barley Response to KCl Placement and Rate
N and P added to soil test recommendation SIP Soil Fertility Rpt, 1968
Broadcast
Side band
Seed row
0
5
10
15
20
25
30
0 15 30 60 90 120 150 180 240
lb K2O/A
Gra
in Y
ield
Incr
ea
se
(bu
/A)
Safe Rates of Seed Row K application (Saskatchewan)
• Seed row application of K2O should not exceed(1 in. spread, 6 to 7 in. rows):
– Cereals – 50 lb K2O/A– Canola – 20 lb K2O/A– Dry pea – 15 lb K2O/A
• Combined P2O5 and K2O in the seed row should also not exceed the recommended safe rates for K2O alone
Source: Saskatchewan Agriculture and Food
Potassium Does Not Cause Roots to Proliferate
• 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
Classen and Barber, 1977
Proportion of roots expected for no K effect (%)
0 20 40 60 80 100
Pro
po
rtio
n o
f ro
ots
ob
ser
ved
in
K s
olu
tio
n (
%)
0
20
40
60
80
100 Corn 17 days old
Be Sure and Use Soil Testing to Monitor Soil K Supplies
Summary—K Nutrition in the NorthernGreat 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 Institute655 Engineering Drive, Suite 110Norcross, GA 30092-2604Phone: 770-447-0335; Fax: 770-448-0439www.ipni.net
Reference #06111