commanditaires de congrÈs / conference sponsors la présence de m. lester vough est rendue possible...
TRANSCRIPT
• COMMANDITAIRES DE CONGRÈS / CONFERENCE SPONSORS
La présence de M. Lester Vough est rendue possiblegrâce à une aide financière du Programme
Innov’Action agroalimentaire issu de l’accord bilatéral Cultivons l’avenir 2 conclu entre
les gouvernements du Canada et du Québec.
Les Vough
Forage Agronomist
Southern Maryland RC & D
&Forage Crops Extension Specialist Emeritus
University of Maryland
&
President, Maryland-Delaware Forage Council
Nitrogen and Potassium
Fertilization of
Cool-Season Grasses
N & K Fertilization Issues/Concerns
Late season (fall) N application to cool-
season grasses
K fertilization of orchardgrass
Why late season N on cool-season grasses?
Increases root growth
-- Enhanced root growth aids in uptake of water & nutrients
-- Helps carbohydrate buildup in stem bases -- Promotes winter survival & initiation of spring
growth
Increases plant density -- enhances formation of crown buds & subsequently new tillers next spring
Increases drought tolerance
Decreases summer weeds
Low rates of N in fall set up the plant for winter and for healthy early spring growth
Principles of late season fertilization
N taken up by roots even though shoot growth has
stopped
N increases chlorophyll content
-- Increased chlorophyll = increased photosynthesis
-- Increased photosynthesis = increased sugars
Plants not growing, so sugars not used for growth – thus stored to enhance winter survival & spring recovery
Sugars make grass plant less susceptible fo freezing
Late season N applications promote deep rooting during the fall, so deeper, healthier roots in spring/summer
Late season fertilization of grasses
General recommendation in Maryland: Do not apply N after mid-Sept – disrupts development of winter hardiness
40-50 lb N/acre mid-Oct to mid-Nov = little top growth but root growth still active
Sometimes increased spring yields, sometimes did not, but never detrimental (Va Tech Univ.)
Likely to be related to more vigorous spring regrowth (Soils & Crops Res. & Develop. Centre, Sainte-Foy, Quebec)
Late season fertilization of grasses
Use highly soluble N sources – organic sources do not provide same effect
Shown to improve root growth, spring growth, stand density, & maintain or improve forage yield (Va Tech Univ. & Soils &
Crops Res. & Develop. Centre, Sainte-Foy, Quebec)
May replace late winter N application but not late spring & summer applications
When is late season in Maryland?
Varies by location
-- Mid- to late October in mountains
of western Maryland
-- Late October to mid-November
elsewhere in Maryland
Roughly around time of the average
killing frost date
When is late season in Canada?
Toronto
-- Early November
Quebec
-- Early/mid-October
Calgary
-- Early/mid-October
Orchardgrass and Reed Canarygrass
(maintenance)
N Recommendation (lb/acre)
Yield Goal (tons/acre)
up to 2 3 4 5 6 & up
Total* 75-100 100-150 150-200 200-250 250-300
Top-dress at green up - - 35-50 60-80 80-100
Top-dress after 1st harvest 35-50 30-50 40-50 50-60 65-75
Top-dress in late summer** - 30-50 35-50 50-60 65-75
Top-dress in late fall*** 40-50 40-50 40-50 40-50 40-50
* For each yield goal, the combined nitrogen from the split applications must not exceed the maximum total N recommendation. ** Top-dress mid-August to early September, depending upon sufficient rainfall to move N into the soil. *** Late fall application (mid- to late October in mountains of western Maryland and late October to mid-November elsewhere in Maryland, approximately the killing frost date) stimulates root growth and leads to a more vigorous stand. If late fall application is not made, add 40-50 lb/acre to the green up application.
TIMOTHY, SMOOTH BROMEGRASS and PERENNIAL RYEGRASS
(maintenance)
N Recommendation (lb/acre)
Yield Goal (tons/acre)
up to 2 3 4 5 & up
Total* 75-100 100-150 150-200 200-250
Top-dress at green up - 30-50 40-60 80-100
Top-dress after 1st harvest 35-50 30-50 40-50 40-50
Top-dress in late summer** - 30-50 40-50
Top-dress in late fall*** 40-50 40-50 40-50 40-50
* For each yield goal, the combined nitrogen from the split applications must not exceed the maximum total N recommendation. ** Top-dress mid-August to early September, depending upon sufficient rainfall to move N into the soil. *** Late fall application (mid- to late October in mountains of western Maryland and late October to mid-November elsewhere in Maryland, approximately the killing frost date) stimulates root growth and leads to a more vigorous stand. If late fall application is not made, add 40-50 lb/acre to the green up application.
Tall Fescue (maintenance – hay or late summer/fall growth not accumulated for late fall/winter grazing)
N Recommendation (lb/acre)
Yield Goal (tons/acre)
Up to 2 tons 3 tons 4 tons 5 tons 6 & up
Total* 75-100 100-150 150-200 200-250 250-300
Top-dress at green up - - 35-50 60-80 80-100
Top-dress after 1st harvest 35-50 30-50 40-50 50-60 65-75
Top-dress in late summer** - 30-50 35-50 50-60 65-75
Top-dress late fall*** 40-50 40-50 40-50 40-50 40-50
* For each yield goal, the combined nitrogen from the split applications must not exceed the maximum total N recommendation. ** Top-dress mid-August to early September, depending upon sufficient rainfall to move N into the soil. *** Late fall application (mid- to late October in mountains of western Maryland and late October to mid-November elsewhere in Maryland, approximately the killing frost date) stimulates root growth and leads to a more vigorous stand. If late fall application is not made, add 40-50 lb/acre to the green up application.
Late fall applications must be from
inorganic, readily available N sources.
Nutrient Management Issues/Concerns
Late fall N application to cool-season
grasses
K fertilization of orchardgrass
What’s Causing the Problem? Cutting or grazing too short and/or too
frequently Insect & other pests (primarily billbugs,
grubs and occasionally aphids and nematodes) are damaging orchardgrass
A disease called leaf streak seems to be prevalent in orchardgrass (other diseases might be a factor)
Improper fertilization Planting on inappropriate sites Compaction
These factors likely interact making the problem complex!
25 N
0
10
20
30
40
50
60
70
0 160 330
K Rate
Sta
nd
Red
uct
ion
330 N
0
10
20
30
40
50
60
70
0 160 330
K Rate
Sta
nd
Red
uct
ion
4" cut
2" cut
Effect of N rate, K rate, and cutting height on stand reduction in orchardgrass harvested at
4-week intervals
Orchardgrass Needs Adequate K
1.75 to 2% K in forage DM to maximize yield without luxury consumption
K below 1.6% DM disrupts N metabolism in plant
Apply 45-50 lb of K2O/ton of hay removed
During the heat of summer avoid high N rates or low cutting heights
N P2O5 K2O Ca Mg
Hay (lb/ton of forage) 50 20 60
Hay (lb/acre) if 4 t/a yield 200 80 240 23 13
Grazing (lb/acre) 6 2 <1 3 <1
How Much Nutrient Does Orchardgrass Remove from the Soil?Orchardgrass N, P2O5 and K20 removal
rates from the soil
Total macronutrients taken up per ton by various forage crops.
Forage Crop
Uptake, lb/ton
N P2O5 K2O
Alfalfa 56 10 60
Clover-grass 50 15 60
Red clover 44 12 66
Coastal bermudagrass 45 12 50
Orchardgrass 50 17 62
Smooth bromegrass 33 13 51
Timothy 37 14 62
Tall fescue 39 19 53
Corn silage 11 5 11
Sorghum-sudangrass 40 15 58
Total macronutrients taken up by various forage crops at selected yield levels.Forage Crop Yield
Level T/A
Uptake, lb/acre
N P2O5 K2O
Alfalfa 8 450 80 480
Clover-grass 6 300 90 360
Red clover 4 175 50 265
Coastal bermudagrass 8 360 96 400
Orchardgrass 6 300 100 375
Smooth bromegrass 5 165 65 255
Timothy 4 150 55 250
Tall fescue 6 231 111 317
Corn silage 25 266 114 266
Sorghum-sudangrass 8 320 122 466
Orchardgrass fertilization:
Applying greater than 50 lb N/ton of forage is not economical and reduces orchardgrass persistence
Potassium fertilization can help overcome some of the deleterious effects of low clipping
5 survey soil samples all low in K
Less stand loss on dairy farms
Summary
Fertilization of hay & pasture crops not only
important for yield but for stand maintenance
& longevity as well
May need to pay more attention to time of
fertilizer applications than we have in the past
While fertilization can help alleviate effects of
some mismanagement practices, let’s not rely
on fertilization to overcome detrimental
practices such as cutting height, soil
compaction, planting on inappropriate sites,
etc.
The End ---- Questions?