IMMOKALEE — It’s an exciting time to be a soil microbiologist because we’re just now realizing how much more there is to learn about the microorganisms that live in soils. Bacteria, fungi and archaea are all important for growing plants.
Some of these microscopic organisms can cause plant diseases, but others make nutrients available for plants and can encourage root growth. Microbiobial diversity in soils varies greatly. Soils can have over 1 billion bacteria in 1 gram of soil - about the weight of a quarter - and there could be over 50,000 species of bacteria in that soil sample.
As a soil microbiologist for the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), my research focuses on the interactions of soil microorganisms in agricultural ecosystems and examining management practices that use this knowledge to improve soil health and agricultural production.
In the last 35 years, we’ve learned that only about 1% of all soil microorganisms can be grown in a laboratory. This means we need to use other methods to study them. Some of the methods soil microbiologists use today were developed to study microorganisms in humans but can be applied to soil research. We extract the DNA from soil microorganisms and use that DNA to identify and count microorganisms. In my research program, we use these and other methods to determine not only which microorganisms are in soils but how microorganisms affect crops.
One of the important contributions of microorganisms to crop production is related to the availability of nitrogen in soil. Nitrogen is a key component of fertilizers and a necessary nutrient for plant growth. For example, microorganisms can change the amount and types of nitrogen in the soil. Some transform atmospheric nitrogen into a form that can be used by plants, while others change the forms of nitrogen in the soil.
Some microorganisms are more common in certain soils, and we can potentially alter soil conditions to increase the numbers and types of microorganisms. One way to enrich the soil environment and soil microbial community in agriculture is to plant cover crops. We plant cover crops, but we don’t harvest them.
Among their benefits, cover crops reduce weeds, decrease erosion and increase organic matter by adding plant material to the soil. Different types of decomposing plant material can change the amount of water and nutrients the soil can provide.
My UF/IFAS colleagues and I are examining how cover crops can improve soil health in agricultural production systems in Florida, from vegetables to citrus. We are studying how cover crops impact soil microorganisms, particularly those microorganisms that are involved in the nitrogen cycle.
Growing cover crops in Florida is different than growing them in other parts of the country. In colder climates, cover crops may be grown in the winter when vegetables are not being produced. In Florida, vegetables are grown during every season except summer. On the other hand, cover crops can be grown all year in citrus groves.
Our research group at UF/IFAS studies and performs experimental plantings at several commercial farms and groves in South Florida. We are eager to continue to work with both our scientific colleagues and growers to improve agricultural practices by understanding soil health.
Strauss is an assistant professor of soil and water sciences at the UF/IFAS Southwest Florida Research and Education Center in Immokalee.