1. Annual vs. Perennial Warm-Season Grasses
Ben Tracy
Department Crop and Soil Environmental Sciences
Virginia Tech

2. Potential Feed Available for Grazing
Warm
Season
Grasses
Forage Yield
Cool Season
Grasses
Apr
Jun
Aug
Oct
Dec
Feb

3. Typical Situation Late July
Warm-season pasture
Cool-season pasture

4. Relative Advantage ☼ Characteristic Annual Warm-Season Grasses
Perennial Warm-Season Grasses
Establishment ☼
Productivity
Forage Quality
Carbon Sequestration/
Nitrogen Retention
Inputs
Short-term cost
Long-term cost
Labor/Management

5. Study Objective
How do annual and perennial warm-season pastures compare when integrated within a cool-season pasture rotation?
Tracy, B.F., M. Maughan, N. Post, D.B. Faulkner Integrating annual and perennial warm-season grasses in a temperate grazing system. Crop Science. 50:2171–2177.

6. Warm-season Pasture (annual or perennial)
Cool-season Pasture

7. Brown Mid Rib Sorghum - Planted 1st week June
Warm-Season
Annual Pastures
Brown Mid Rib Sorghum - Planted 1st week June

8. Warm Season Perennial Pastures
(Eastern gamagrass, big and little bluestem)

9. -------------------g m -2-----------------
Forage Biomass over Three Years
2005†
2006
2007
July
g m
Fescue
252 a
148 c
258 b
Annual WSG
215 a
291 b
349 b
Perennial
NWSG
285 a
903 a
1373 a
August
245 c
142 b
180 b
883 a
177 b
313 a
360 b
440 a
322 a

10. (received 3+inches rain day after
June 21, 2006
Weeds!
Pigweed and Foxtail
Eastern gamagrass
Perennial WS pasture
Annual WS pasture
(received 3+inches rain day after
planting)

11. Forage Quality in 2006- 2nd year of study
July†
August
Fescue
Peren.
WSG
AnnualWSG
LSD 0.05
CSG
NWSG
Annual
2006
CP†
13.8 a
7.4 b
15.2 a
2.1
16.1 a
9.2 b
15.6 a
3.6
ADF
40.8 b
47.1 a
36.3 c
3.1
37.4 b
47.9 a
37.7 b
5.3
NDF
69.1 b
80.5 a
57.2 c
5.2
66.4 b
81.5 a
56.8 c
8.1

12. ------------dollars ha -1---------------
Variable Costs for Pasture Types
Perennial WSG
Annual WSG
2004
2005
2006
2007
Total
dollars ha
Seed
64.5 -
6.4
12.0
24.8
Fertilizer
13.7
9.5
12.5
35.7
Field Op.
20.0 20
14.7
5.4
19.7
39.8
Herbicide
7.6
1.4
9.0
6.1
18.9
92.0
93.4
40.9
27.6
50.7
119.2

13. Preliminary Conclusions
Perennial WS pastures may be more dependable in terms of forage availability if climate varies substantially.
Annual and perennial WS both work well to fill in summer slump, but there may be an “overlap” in productivity during June that requires added management.
Nutritive value on much higher annual pasture, which may benefit some types of livestock.
Variable costs ‘add up’ quickly for Annual WS pastures.

14. Managing clover in permanent pastureland

15. How much N fertilizer is clover worth?
Urea Fertilizer
Assume nitrogen is $.50/lbs.
Applying 40lbs N as urea costs about $20/acre.
Common N response on tall fescue/orchardgrass would increase forage yield by 30%.
Clover
Assume white clover $4/lbs
Applying 2 lbs clover seed costs about $8/ac.
With 25-30% clover stand should give you about 40 lbs N.
With 30 % clover should expect average 30% increase in forage yield (grass + clover).

16. Pros and Cons Urea Clover Immediate forage response (usually).
Increases fescue toxins.
Effect on cattle performance?
Increases soil organic matter.
Minimal effect on drought resistance.
Increases CO2 emissions to atmosphere.
Re apply every year.
Clover
May take months to see forage response.
Dilutes fescue toxins.
Improves cattle performance.
Increases soil organic matter.
Improves pasture drought resistance (red clover).
Neutral or decreases CO2 emissions to atmosphere.
May need to re seed every 3 years (red clover).

17. Keys to successful frost seeding
1) Reduce standing dead vegetation to 1 inch stubble before overseeding (e.g., mob graze). 2) Frost-seed early during 1st week February. 3) Aggressive rotational grazing in spring to reduce grass competition and allowed clovers to grow enough to establish. 4) Make sure soil fertility is good (adequate P, K and pH) to stimulate clover growth. 5) Hope for good rainfall...