Reduce soil toxicity by adding minerals to irrigation water

According to the scientists, soil enriched with ferrihydride has the potential to reduce concentrations of arsenic and uranium - elements that pose a threat to human health.

Arsenic, uranium and other trace elements naturally occur in soils throughout the Corn Belt of the Midwest, including the state of Cornhusker.

Plants grown on soils containing high levels of these trace elements can absorb them through their roots. These elements have the ability to inhibit plant growth and threaten the health of those who regularly consume them.

Immediate addition of ferrihydride to irrigation water can limit concentrations of toxic elements.

Researchers Arindam Malakar, Chittaranjan Ray and colleagues at the University of Nebraska-Lincoln looked to see if ferrihydrite could help solve this problem. Ferrihydrite is a nano-mineral that can be found in soil, but is also used to treat groundwater and drinking water.

As part of a trial in a land-use greenhouse from the university's Panhandle Research and Extension Center, the team grew corn on three soils: One without ferrihydrite, another with 0.05% ferrihydrite and a soil with 0.10% minerals.

After watering the soil with water fortified with arsenic and uranium, the researchers monitored the growth of the corn plants. They also monitored the concentration of trace elements in the water around the plant roots.

The team found that soils enriched with ferrihydride were able to reduce concentrations of arsenic and uranium by about 20 percent. This soil also seems to reduce nitrate loss by 30 - 50%.

Nitrates are essential for plant growth, but can cause health problems when they get into groundwater. Meanwhile, the soil's water holding capacity increased from about 13% in the absence of ferrihydride to about 17%.

It is important that maize also benefits from this type of soil. Plants grown in ferrihydride-rich soil grow taller, producing about 12-15% more living tissue. At the same time, the plant can also synthesize more chlorophyll and produce seeds that contain almost twice the amount of iron.

Conducting similar experiments under actual field conditions, rather than greenhouses, would be necessary to confirm the results of the study, the researchers say.

Preliminary findings show that adding even small doses of ferrihydride to irrigation water can limit concentrations of toxic elements. At the same time, promote plant growth and nutrient absorption.