Switchgrass biomass yield and composition and soil quality as affected by treated wastewater irrigation in an arid environment

Authors: CHAGANTI, VIJAYASATYA - Texas A&M Agrilife; GANJEGUNTE, GIRISHA - Texas A&M Agrilife; MEKI, NORMAN - Texas Agrilife Research; Kiniry, James; NIU, GENHUA - Texas A&M Agrilife

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2021
Publication Date: 6/19/2021
Citation: Chaganti, V., Ganjegunte, G., Meki, N.N., Kiniry, J.R., Niu, G. 2021. Switchgrass biomass yield and composition and soil quality as affected by treated wastewater irrigation in an arid environment. Biomass and Bioenergy. 151. Article 106160. https://doi.org/10.1016/j.biombioe.2021.106160.
DOI: https://doi.org/10.1016/j.biombioe.2021.106160

Interpretive Summary: Scarcity of fresh water (FW) scarcity due to drought has reduced its availability to agriculture in the arid west Texas region. Using treated urban wastewater (TWW) for agricultural irrigation as an alternative has great promise. However, soil salinization of TWW could be detrimental to crops and soil quality. Crops needing less irrigation and that are salt-tolerant are needed to sustain this region's agriculture. Perennial switchgrass is well adapted to grow on marginal lands and is useful for bioenergy. However, its performance when irrigated with TWW is largely unknown. This field study evaluated the yield potential and composition of switchgrass when irrigated with TWW along with soil quality changes. Plant production was not affected by TWW irrigation and there were no significant differences between TWW and FW. Cellulose and lignin contents were lower, while ash content was higher in TWW treatment. Theoretical ethanol production was not affected. Soil salinity and sodicity increased over time under TWW irrigation. However, application of gypsum and sulfur reduced soil sodicity. Thus, switchgrass tolerates soil salinity induced by TWW application and can be successfully grown on these marginal arid soils for bioenergy.

Technical Abstract: Freshwater (FW) scarcity as a result of prolonged drought has reduced FW availability to agriculture in the add west Texas region in order to meet demands from other sectors. Alternatively, there is enormous potential to utilize treated urban wastewater (TWW) for agricultural irrigation. However, the soil salinization potential of TWW is a concern as it can be deufo1ental to crops and soil quality. Alternative crops that are both less water­intensive and salt-tolerant are therefore needed to sustain this region's agriculture. Switchgrass is a perennial grass that is well adapted to grow on marginal lands and is a novel crop for lignocellulosic bioenergy feedstock. However, its perfonnance when irrigated with TWW on arid soils of far west Texas is largely unknown. This field study evaluated the yield potential and composition of switchgrass biomass as affected by TWW along with soil quality changes, using a split-plot experimental design. Results indicate that biomass yields were not affected by TWW irrigation and there were no significant differences between TWW and FW across years. With respect to biomass composition, cellulose and lignin contents were lower, while ash content was significantly higher in TWW treatment. Theoretical ethanol production was not affected. Soil salinity and sodicity increased overtime but this increase was more prominent under TWW irrigation. However, application of gypsum and sulfur significantly reduced soil sodicity. These results indicate that switchgrass can tolerate soil salinity induced by TWW application and therefore can be successfully grown on these marginal arid soils as a bioenergy feedstock.