Oat for Forage

Conservation Tillage Fact Sheet

Oat for Forage: Production, Quality and Water Use

R. L. Anderson - USDA-ARS, Akron, CO

The Fact: With producers seeking alternative crop rotations to replace winter wheat-fallow, oat supplies an early spring option for crop diversity.

Oat is a cool-season crop that is commonly harvested for forage. With producers seeking alternative crop rotations to replace winter wheat - fallow, oat supplies an early spring option for crop diversity.

We examined the forage production, quality, and water use of Hy-Test oat at the ARS station near Akron. Oat was planted at 60 lbs/acre on April 1, April 15, and May 1. Nitrogen was broadcast at 50 lbs N/acre. Forage was harvested at the heading, anthesis, milk, and dough growth stages.

Production

Planting date. Oat yields the highest when planted on April 1 (Figure 1). Yields decreased 15 and 20% when oat was planted on April 15 and May 1, respectively. We also have planted oat in early March in previous years, but yield is usually 15 to 20% less than planting in early April. Yields over several years have ranged from 1000 to 6000 lbs/acre, varying with rainfall and temperature.

Growth Stage at Harvest. Oat yields the highest when harvested at the milk stage (Figure 2). Yield decreases by 15% if harvest is delayed until the dough stage. The earlier harvests also produce less forage, with yield 29% less if oat is harvested at anthesis.

Forage Quality

Harvesting oat at the heading stage produces the highest quality forage, with crude protein near 18% and total digestible nutrients of 66% (Table 1). Harvesting oat later in the growing season reduces its quality. However, pounds of protein produced per acre is highest when oat is harvested at the milk growth stage. Harvesting oat at the heading stage also produces high protein quantity per acre because of its protein concentration.

Table 1. Forage quality and water use efficiency of oat as affected by growth stage at harvest.
Growth Stage	Crude Protein	Protein^a	ADF^b	TDN^c	WUE^d
	(%)	(lbs/ac)	(%)	(%)	(lbs/DM/in)
Heading	17.7	510	33	66	220
Anthesis	12.6	460	38	60	260
Milk	11.5	600	39	59	350
Dough	10.8	460	39	59	240
^aProtein (lbs/ac) = forage quantity multiplied by protein (%) ^bAcid Detergent Fiber ^cTotal Digestible Nutrients ^dWater Use Efficiency = lbs of dry matter divided by water use

Water Use

Total water use by oat can range from 10 to 15 inches, depending on the growing season. Also, water use is related to time of harvest, with water use being 25% less when oat is harvested at the heading stage compared to harvesting in the dough stage.

Water use efficiency, however, is highest when oat is harvested at the milk stage, with 350 lbs of dry matter produced per inch of water used (Table 1). In contrast, water use efficiency per unit of protein declines with the later harvests. Oat harvested at heading produces 39 lbs of crude protein per inch of water used, while forage harvested at the milk stage produced 30 lbs of crude protein/inch of water, a decrease of 23%.

USDA-ARS and Colorado Conservation Tillage Association Fact Sheet # 3-97.
By: R.L. Anderson
The technical assistance of D. Fritzler and K. Reule is gratefully acknowledged.