Although an increasing number of producers are introducing compost into their production systems, they still have a need for fertilizers.
That’s because compost only contributes a limited amount of nutrients to the soil, emphasizes Monica Ozores-Hampton, assistant professor and vegetable specialist at the Southwest Florida Research and Education Center in Immokalee.
“But applying organic matter is a great way to increase sustainability,” she says. “You are putting back something in the soil.” Compost has many uses in vegetables.
It’s used for transplant production, it can replace potting soil media, it’s used in seed production and, when it’s mature and stable, can help suppress soil-borne diseases if used as a substitute for plastic mulch.
“You can even use compost to reduce weeds in the field by applying immature compost with high acetic acids,” she says.
But it’s most common field use is as a soil amendment that increases soil tilth and helps fertilizer work more efficiently in open beds or plastic mulch-covered beds, Ozores-Hampton says.
Unless it’s specifically registered as a fertilizer, she says, “Compost is a soil amendment.” You can, however, calculate the nitrogen, phosphorus, potassium and micronutrients the compost contains and reduce the amount of fertilizer you use.
Compost is commonly used with vegetables, especially leafy greens, in citrus and peach groves, and with blueberries and raspberries. When you use compost, you basically put a buffer in the soil that protects the plant from some of the destructive effects of the environment—especially at the root zone level, Ozores-Hampton says.
The plant is better able to obtain water and nutrients and will grow better, have better biomass and better root mass. A strong root mass, she says, helps plants fight off diseases, nematodes and other threats.
Subbing for fertilizer
Pete Stoffella, professor and center director of the University of Florida’s Institute of Food and Agricultural Sciences’ Indian River Research and Education Center at Fort Pierce, and his collaborators are conducting research using biodegradable waste byproduct—or compost—as a partial substitute for inorganic fertilizer.
Specifically, they’re studying whether organic materials can reduce the amount of nitrogen and phosphorus in surface water runoff with vegetables and citrus while maintaining the same yields and quality of vegetables and fruit as with inorganic fertilizers.