Cover Crops: Sorghum, Sudangrass
Table of Contents
- Description: Family
- Cover Crop Use
- Growth Habits
- Sensitivity to Herbicides
- Weed Control
- Benefits and Concerns
- Getting Started
- Managing the Cover Crops
- Related Links
Description
Figure 1: Sorghum and sudangrass are warm season
grass cover crops that can provide good weed suppression, grazing
and forage supply, in addition to the soil structure improvements
that can be expected from grasses.
Family
- Grass – summer annual
- Refers to a wide range of grasses related to sorghum and sudangrass
- Usually a cross between a forage or grain sorghum and sudangrass
Germination
- Requires warm soil for germination – above 12°C)
Top Growth
- Rapidly growing summer annual grass
- Wide cultivar variation – height ranges between 45 cm to
over 5 m.
- Has lower leaf area than corn
Root System
- Has more secondary roots than corn
- Roots can reach depth of greater than 124 cm
Figure 2: Root mass late in fall may be reduced.
Overwintering
Site suitability
- Extreme drought tolerance
- Prefers neutral pH but can tolerate 5.0 to 9.0
- Tolerant of salinity
Sensitivity to Herbicides: Weed Control
There are no herbicides registered for weed control in sorghum
sudan grasses. Use narrow rows and appropriate agronomic practices
to establish a vigorous crop canopy as soon as possible.
Benefits and Concerns
Nutrient Management
- heavy feeder due to crop biomass
- may need additional nitrogen to aid in decomposition
Figure 3: Longer term growth of a cover crop
like sorghum shades and moderates soil temperatures; encouraging
more earthworms.
Pest Management
- nematode suppression – selected varieties only
- weed suppression from competition for light, water and nutrients
Organic Matter
- can produce massive amounts of dry matter (4,000 to 5,000 lbs/acre)
- chop plant down when it reaches 1-1.2 m to encourage tillering
and deeper root growth
- manage the crop with chopping to avoid maturity as stalks get
fibrous and woody with age and slow to break down
Erosion Control
- reasonable, soil conservation alternative to summer fallowing
As Feed
- can be used as forage
- wait until mature to avoid problems with prussic acid
- do not feed if plants have been stressed or frozen
Getting Started
Establishment
- Plant in warm soils – no sooner than 2 weeks following
corn
Cost & Availability
- There is a wide variation in cultivars available and some confusion
with sorghum
- Cost is moderate depending on the variety
- Some varieties have nematode suppressing properties;
- BUYER BEWARE: Make you sure know what you’re buying
when getting seed
Managing the Cover Crops
- chop or mow plant when it reaches 1-1.2 m. to encourage tillering
and deeper root growth
- manage the crop with chopping to avoid maturity as stalks gets
fibrous and woody with age and slow to break down
- will set seed if not mowed
Figure 4: Sorghum and sudan grass hybrids will
go to seed if not mowed, creating a potential weed problem.
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