COMMANDITAIRES DE CONGRÈS / CONFERENCE SPONSORS La présence de M. Lester Vough est rendue possible grâce 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  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) * 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.

TIMOTHY, SMOOTH BROMEGRASS and PERENNIAL RYEGRASS (maintenance) N Recommendation (lb/acre) * 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.

Tall Fescue (maintenance – hay or late summer/fall growth not accumulated for late fall/winter grazing) N Recommendation (lb/acre) * 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.

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!

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 lb of K 2 O/ton of hay removed  During the heat of summer avoid high N rates or low cutting heights

NP2O5P2O5 K2OK2OCaMg Hay (lb/ton of forage) Hay (lb/acre) if 4 t/a yield Grazing (lb/acre)62<13 How Much Nutrient Does Orchardgrass Remove from the Soil? Orchardgrass N, P 2 O 5 and K 2 0 removal rates from the soil

Total macronutrients taken up per ton by various forage crops. Forage Crop Uptake, lb/ton N P 2 O 5 K 2 O Alfalfa Clover-grass Red clover Coastal bermudagrass Orchardgrass Smooth bromegrass Timothy Tall fescue Corn silage115 Sorghum-sudangrass401558

Total macronutrients taken up by various forage crops at selected yield levels. Forage CropYield Level T/A Uptake, lb/acre N P 2 O 5 K 2 O Alfalfa Clover-grass Red clover Coastal bermudagrass Orchardgrass Smooth bromegrass Timothy Tall fescue Corn silage Sorghum-sudangrass

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 ?