Capacity of plants to accumulate sulfur and improve the quality of livestock drinking water

Authors: Reinhart, Kurt; Petersen, Mark; Muscha, Jennifer - Boyle

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2021
Publication Date: 7/21/2021
Citation: Reinhart, K.O., Petersen, M.K., Muscha, J.M. 2021. Capacity of plants to accumulate sulfur and improve the quality of livestock drinking water. Rangeland Ecology and Management. 78:100-103. https://doi.org/10.1016/j.rama.2021.06.005.
DOI: https://doi.org/10.1016/j.rama.2021.06.005

Interpretive Summary: Problem - High levels of dissolved sulfate in drinking water can adversely affect livestock performance and cause ruminant death. Established treatment options include reverse osmosis and water softening with calcium hydroxide. Less clear is whether bioremediation (or other) technologies may be used to efficiently purify livestock drinking water on rangelands. Accomplishment - We found that sulfur-hyperaccumulator plants can grow and survive in a rangeland wetland environment. Unfortunately, even the best sulfur hyperaccumulating plants are likely to store less than 0.0002 kg of sulfur per plant while rangeland water sources with high sulfate concentrations (>1,000 PPM) may contain many kilograms of sulfur. We interpret that planted artificial floating islands are likely to be too costly and time consuming (i.e. plant and harvest year-after-year) relative to the islands’ capacity to reduce SO4 concentrations.

Technical Abstract: High levels of dissolved SO4 in drinking water can adversely affect livestock performance and cause ruminant death. Some plant species may help to remove SO4 and purify drinking water, especially S-hyperaccumulators. However, little is known about the capacity of S-hyperaccumulators to grow in a rangeland wetland environment(s). Here we measured the survival, shoot mass, shoot S concentration, and S mass (mg × plant-1) of nine plant species. Plants were grown in a wetland environment on an artificial floating island in a mesocosm supplied with high SO4 water (2,430 to 4,730 PPM) from a rangeland reservoir. Water properties were measured throughout the experiment. We found a strong positive relationship (r2= 0.98) between total dissolved solids (TDS) and SO4. The nine planted species functioned as S-hyperaccumulators during the mesocosm experiment, and their average sulfur concentration was 3.8 times greater than the average of 39 species from the literature. Among the nine species, Brassica napus L., B. napus var. pabularia (DC.) Rchb., and B. septiceps (L.H. Bailey) L.H. Bailey in the mustard family (Brassicaceae) tended to have the greatest shoot S concentrations. The total S mass per plant was 5 times greater for B. septiceps (44 mg × plant-1) than B. juncea (L.) Czern. We found no other appreciable differences in total S mass among species. To help address the problem of scaling a planted artificial floating island, we used our data and data from the literature to parameterize simulations and estimate the number of plants needed to reduce the SO4 concentration of a small volume of livestock drinking water (4,542.5 L and 2,000 PPM) to a recommended limit (1,000 PPM). The simulations suggest that =9,005 B. septiceps or =2,769 B. oleracea L. plants would be needed to reduce the water’s SO4 concentration to that limit. Given the small amount S removed (per plant) relative to the vast amount of dissolved SO4 possible in a rangeland water source(s), we interpret that planted artificial floating islands are not likely to be a practical tool for reducing SO4 in livestock drinking water compared to other technologies, like reverse osmosis and water softening.