Soil microbiologist Sarah Strauss kicked off a Biochar and Compost Workshop at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center in mid-July. Strauss, a UF/IFAS associate professor, focused on the importance of soil health for citrus.
She began with a U.S. Department of Agriculture Natural Resources Conservation Service
definition of soil health. According to that definition, soil health is the continued capacity of a soil to function as a vital living ecosystem that sustains plants, animals and humans.
Soil health presents a unique challenge in Florida’s sandy soils where organic matter is very low. “In Florida, we are basically growing in beach sand,” Strauss said. “Our soils are about 98% sand, so you are lucky if you have 1% organic matter in your soils.”
Strauss, who has been studying compost and its ability to improve soil health, said Florida’s hot and humid climate presents challenges because compost applied to groves decomposes quickly. The climate in a sense supercharges the soil microbes, which feed on the compost.
Strauss’ research has demonstrated that compost applications do have an effect on soil health. One trial she conducted was in a plot where soil organic matter was below 1% prior to compost application. After two applications (10 tons per acre around trees) of compost in year one, the soil organic matter had moved up to just about 1.5%.
“The controls actually increase a bit, also, probably because this area had not had citrus grown in a while,” Strauss said. “Now we have some weeds growing around there, so there are other inputs going into the soil. This is an ongoing trial, so we hope that organic matter keeps creeping up in our compost plots over time.”
Strauss told growers that it will take several years of multiple compost applications to increase the organic matter. “You must keep adding this compost material to help build up this resource, so these microorganisms are not starving,” she said. “Our hot and humid climate makes the microbes eat the compost fast, which means it is not going to have to happen overnight.”
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