Revised N Fertilizer Recommendations for Cool-Season Grasses Les Vough Forage Agronomist Southern Maryland RC & D & Forage Crops Extension Specialist Emeritus University of Maryland
What are the revisions? Cleaning up some discrepancies but basically not changing the overall total rates Adding a late fall N application Reducing green up N application rate
Why late fall N on cool-season grasses? Increases root growth enhanced root growth aids in uptake of water & nutrients, which 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
Late fall fertilization of grasses General recommendation: Do not apply N after mid-sept disrupts development of winter hardiness 40-50 lb N/ac 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)
Late fall 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) May replace late winter N application but not late spring & summer applications
When is late fall? 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
Tall Fescue Current (maintenance) N Recommendation (lb/a) Up to 2 tons Yield Goal (T/A) 3 tons 4 tons 5 tons 6 & up Total* 50-100 100-150 150-200 200-250 250-300 Top-dress at green up 25-50 50-75 75-100 100-125 125-150 Top-dress after 1 st harvest 25-50 2030 30-40 40-50 50-60 Top-dress in late summer** - 30-45 45-60 60-75 75-90 * 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.
Tall Fescue -- Revised (maintenance hay or late summer/fall growth not accumulated for late fall/winter grazing) N Recommendation (lb/a) Up to 2 tons Yield Goal (T/A) 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 1 st 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.
Tall Fescue -- Revised (maintenance accumulated for late fall/winter grazing, i.e., fall-saved fescue pasture) N Recommendation (lb/a) Up to 2 tons Yield Goal (T/A) 3 tons 4 tons 5 tons 6 & up Total* 75-100 100-150 150-200 200-250 250-300 Top-dress at green up 50 60-90 60-80 80-100 100-120 Top-dress after 1 st harvest - - 45-60 60-75 75-90 Top-dress in late summer** 25-50 40-60 45-60 60-75 75-90 * 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.
Orchardgrass and Reed Canarygrass -- Current (maintenance) N Recommendation (lb/a) Yield Goal (T/A) up to 2 3 4 5 6 & up Total* 60-100 110-150 160-200 210-250 260-300 Top-dress at green up 30-50 50-70 80-100 100-120 130-150 Top-dress after 1 st harvest 30-50 30-40 40-50 55-65 65-75 Top-dress in late summer** - 30-40 40-50 55-65 65-75 * 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.
Orchardgrass and Reed Canarygrass -- Revised (maintenance) N Recommendation (lb/a) Yield Goal (T/A) 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 1 st 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 -- Current (maintenance) N Recommendation (lb/a) Yield Goal (T/A) up to 2 3 4 5 & up Total* 90-140 140-180 180-230 230-280 Top-dress at green up 50-70 60-80 80-100 100-120 Top-dress after 1 st harvest 40-70 40-50 60-80 80-100 Top-dress in late summer** - 40-50 40-50 50-60 * 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.
TIMOTHY, SMOOTH BROMEGRASS and PERENNIAL RYEGRASS -- Revised (maintenance) N Recommendation (lb/a) Yield Goal (T/A) 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 1 st 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.
Late fall applications must be from inorganic, readily available N sources.
The End ---- Questions?