Cover Crops Promising, But …

Scientist Sarah Strauss has learned some interesting and promising things about the use of cover crops in Southwest Florida citrus over the past 2.5 years. But the University of Florida Institute of Food and Agricultural Sciences researcher has not yet found that cover crops provide what growers seek most — increased yields. Use of the crops has also not yet caused changes in tree canopy or roots.

Strauss was one of several presenters in a July virtual educational session hosted by the Citrus Research and Development Foundation and Florida Citrus Mutual.

One of the promising things Strauss has discovered is that use of the crops resulted in a significant increase in soil organic matter and microbial abundance. She also discovered that soil nitrogen increased where legume crops were used, and that the crops reduced weed pressure in treated row middles, which reduced mowing frequency. In addition, she reported that the crops changed soil microbial nitrogen cycling. She said it could take several years before increases in soil health influence tree health and productivity.  

The research Strauss focused on in her presentation was a Southwest Florida citrus plot with 20-year-old trees. The cover crops were planted in row middles, and there were multiple plantings per year.

Strauss started her presentation with a general discussion of cover crops. She said they are planted to benefit the soil, and generally are not harvested for profit. Farmers plant the crops to reduce weeds, soil erosion and soil compaction, and to increase soil organic matter, which can influence plant growth, she said.  

Perennial cover crops include perennial peanut and bahia grass. Annual cover crops include cowpeas, sunn hemp, vetches, crimson clover, cereal rye, wheat, millets, buckwheat, sorghum-sudangrass and daikon radish.

“We’ve had great success with sunn hemp,” Strauss said. Sunn hemp is a legume.

Strauss joined UF/IFAS in 2016; learn about her background.

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