Revised N Fertilizer. Recommendations for. Cool-Season Grasses

Transcription

1 Revised N Fertilizer Recommendations for Cool-Season Grasses Les Vough Forage Agronomist Southern Maryland RC & D & Forage Crops Extension Specialist Emeritus University of Maryland

2 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

3 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

4 Late fall fertilization of grasses General recommendation: Do not apply N after mid-sept disrupts development of winter hardiness 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)

5 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

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9 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

10 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* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** * 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.

11 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* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** Top-dress late fall*** * 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 lb/acre to the green up application.

12 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* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** * 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.

13 Orchardgrass and Reed Canarygrass -- Current (maintenance) N Recommendation (lb/a) Yield Goal (T/A) up to & up Total* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** * 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.

14 Orchardgrass and Reed Canarygrass -- Revised (maintenance) N Recommendation (lb/a) Yield Goal (T/A) up to & up Total* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** Top-dress in late fall*** * 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 lb/acre to the green up application.

15 TIMOTHY, SMOOTH BROMEGRASS and PERENNIAL RYEGRASS -- Current (maintenance) N Recommendation (lb/a) Yield Goal (T/A) up to & up Total* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** * 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.

16 TIMOTHY, SMOOTH BROMEGRASS and PERENNIAL RYEGRASS -- Revised (maintenance) N Recommendation (lb/a) Yield Goal (T/A) up to & up Total* Top-dress at green up Top-dress after 1 st harvest Top-dress in late summer** Top-dress in late fall*** * 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 lb/acre to the green up application.

17 Late fall applications must be from inorganic, readily available N sources.

18 The End ---- Questions?