Cover Crops

Cover crops are an alternative way to manage soil fertility in agricultural systems; they can be a living mulch or incorporated into the soil as a green manure. Sometimes one crop can cover multiple needs.

Florida’s sandy soils tend to have low soil fertility as well as low water and nutrient retention because of their low organic content. Cover crops increase soil fertility by adding organic matter.

Farmers can grow cover crops between crop cycles (such as vegetables) or intercropped among crops (such as ground cover in orchards).

Cover Crop Uses

Cover crops are sown to:

  • Control weeds through competition for available space, light, water, and nutrients
  • Prevent soil erosion caused by heavy rainfall or winds
  • Protect crops (such as watermelon) from sand blasting damage
  • Retain and harvest residual nutrients that would be leached in the off-season
  • Recycle and restore nutrients in a crop system
  • Reduce select harmful nematode populations
  • Create additional income (such as hay production)
  • Provide mulch cover for row middles and/or mulched beds
  • Provide habitat for beneficial insects and birds

Although cover crops have many benefits, improper selection of cover crop types can create challenges. Some may be too weedy, woody, and/or tall, which can interfere with cultivation and harvest. Others may harbor pests and diseases.

Some of these challenges can be avoided by cultural practices such as mowing, but the easiest way to prevent unwanted effects is to identify and plant cover crops that suit your needs.

Types of Cover Crops

The main distinction in cover crops is between annual cover crops intended for a season and perennial crops that will last for many years. Annual crops can be grains/grasses or legumes (those that produce nitrogen), and are either summer or winter crops. Winter cover crops are adapted to shorter, cooler days, while summer crops are better for hot, long-hour days.

Choosing a Crop

Species suited for cover cropping in Florida are listed below in Table 1. Because of South Florida's climate, winter cover crops may not be ideal choices for cultivation. Crops appropriate for South Florida are marked with an asterisk.

Cover crops can be chosen for purposes such as soil protection, nitrogen production, or creating residues for incorporation into the soil. Variables such as decomposition rates, herbage (biomass), and classification determine how well a cover crop is suited to a specific purpose.

Finding the best cover crop for your specific needs may take some patience and experimentation with different crops, crop combinations, management practices, and use of appropriate technology. Growing multiple species can increase the performance and adaptability of a cover cropping system, especially when growing conditions are less favorable for one of the species.

Cover cropping was a large part of past Florida farming practices, so it may be worthwhile to take advantage of the experience and knowledge of older farmers in your region who farm similar soils and have used cover crops successfully.

Table 1.  Cover crops for Florida (*South Florida compatible)

Crop & Seeding Date

Yield-Biomass (lbs / acre)

Yield-Nitrogen (lbs / acre)

Seeding Rate (lbs / acre)

Annual Winter Cover Crops

Leguminous

 

 

 

Crimson Clover
Oct. 1 – Nov. 15

1500 – 5000

35 – 120

20 – 25

Hairy Vetch
Oct. 1 – Nov. 15

2000 – 4000

35 – 150

20 – 30

Lupine*
Oct. 1 – Nov. 15

2000 – 4500

45 – 120

30 – 45

Grain

 

 

 

Black Oats
Oct. 1 – Nov. 15

1500 – 3500

20 – 40

80 – 100

Winter Rye
Oct. 15 – Nov. 15

3000 – 6000

30 – 50

80 – 100

Annual Summer Cover Crops

Leguminous

 

 

 

Aeschynomene*
Mar. 1 – June 30

2000 – 4000

50 – 100

6 – 8

Cowpeas*
Apr. – Aug.

4000 – 6000

50 – 90

6 – 8

Hairy Indigo
Mar. 15 – May/June

7 – 10 tons of greenchop/acre

80 – 150

6 – 10

Sunhemp*
Mar. 1 – June 30

4500 – 10,000

90 – 180

30 – 50

Velvetbeans*
Mar. 1 – June 30

2200 – 4000

50 – 85

30 – 50

Grain

 

 

 

Sorghum-sudan
Mar. 1 – June 30

6500 – 9500

55 – 80

24 – 30

Perennial Cover Crops

Leguminous

     

Rhizoma Peanut
Dec. – Mar.

2000 – 10,000
(12 months)

50 – 130

80 – 100 bu of rhizomes/acre

Grass

     

Bahiagrass*
Jun. - Aug. if rainfed

3000 – 8000

55 – 140

15 – 20


Adapted and excerpted from:

Y. Newman, et al, Cover Crops (SS-AGR-66), Agronomy Department (rev. 11/2010).

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