Every summer, nearly 10,000 acres of rice are grown in the Florida Everglades agricultural region, an approximately 1,100-square-mile area south of Lake Okeechobee.

Farming here requires a delicate touch. Due to a process called subsidence, the area has lost almost 1.8 metres of soil in the last century.

One way to slow this subsidence and preserve the nutrient-rich soil is to flood the area during Florida’s rainy season and use the fields to grow rice. The fields are flooded with water from the adjacent canals. Once the water dries up or seeps away, the rice is harvested.

The Conversation asked Associate Professor Jehangir Bhadha, a soil sustainability expert at the University of Florida, how the university got into rice farming and the environmental benefits it brings.

What is the story behind rice cultivation in the Everglades?

In the 1950s, rice was grown for a short time in the Everglades Agricultural Area, but it was limited to about 2,000 acres (800 hectares).

Then a rice virus called Hoja Blanca, the so-called white leaf virus, was discovered in Florida, which causes the plants to stunt or even die. This virus was first reported in Colombia and Venezuela in the late 1950s.

Rice made a comeback in Florida in 1977 after farmers in the Everglades Agricultural Area demonstrated that it could be grown in sugarcane fields during the summer fallow period from May to August – when it is too hot and wet to grow vegetables in South Florida. By this time, Hoja Blanca disease was under control and new resistant rice varieties were being developed.

In the late spring and summer, more than 20,000 acres of fallow sugarcane land in the Everglades Agricultural Area are available for rice cultivation. In 2023, about half of those acres were planted with rice. The remaining land is either fallow or flooded but does not produce rice – a practice commonly referred to as “fallow flooding.”

On average, about 2 tons (1,800 kilograms) of rice are produced per hectare of cultivated land.

What makes rice cultivation in this area so special?

Rice cultivation in the Everglades Agricultural Area does not require initial fertilization with nitrogen, phosphorus or potassium because the region’s soils are highly organic and nutrient-rich.

The area consists of nearly 450,000 acres (180,000 hectares) of organic soils known as Histosols. These soils contain up to 80% organic matter, making them unique to the region and an important resource for its thriving agriculture. Histosols are also sometimes called bog or peat soils.

The Histosols of South Florida formed over a period of several thousand years when organic matter accumulated faster than it could decompose in the flooded sawgrass prairies that flourished in the area south of Lake Okeechobee.

But since the land here was drained for agriculture in the early 20th century, organic material has been decomposing faster than it can grow back. This is mainly due to microbially mediated oxidation, which occurs when organic material is slowly decomposed and consumed by microbes, leading to a gradual loss of soil and a lowering of surface elevation.

The soil depth in this area varies from a few centimeters to up to 1.5 meters. Beneath the Histosols lies hard limestone rock that is not suitable for agriculture. In many places the limestone rock is exposed on the surface or parts of it are incorporated into the soil.

What contribution does rice cultivation make to soil health there?

By flooding fields for longer periods, farmers suppress both the microbial activity that causes oxidation and the hatching of pests. It also increases the water-holding capacity of the soil, allowing for greater moisture retention during drier seasons.

Improved soil health benefits the sugarcane crop and maximizes soil longevity.

Flooded rice cultivation has also been shown to attract waders such as the great egret, the snowy egret and the glossy ibis.

What work is your team currently doing?

In the last 15 years, more rice and more varieties of rice have been grown. While in 2008 only two dominant varieties were grown on around 4,800 hectares, by 2023 there were already more than 10 varieties on 9,300 hectares.

To ensure a continuous supply of new varieties, researchers and others at the University of Florida’s Institute of Food and Agricultural Sciences, along with Florida Rice Growers Inc., conduct annual rice variety trials to evaluate new or existing varieties in South Florida. The goal of the trials is to identify high-yielding, disease-resistant rice varieties that are compatible with the region’s subtropical climate and highly organic soils.

Every summer, the faculty and research team at IFAS at the University of Florida host a Rice Field Day to present their latest research findings.

This article is republished from The Conversation under a Creative Commons license. Read the original article.