Yield response of canola as a biofuel feedstock and soil quality changes under treated urban wastewater irrigation and soil amendment application

Authors: CHAGANTI, VIJAYASATYA - Agrilife Research; GANJEGUNTE, GIRISHA - Agrilife Research; NIU, GENHUA - Agrilife Research; ULERY, APRIL - New Mexico State University; ENCISCO, JUAN - Agrilife Research; FLYNN, ROBERT - New Mexico State University; MEKI, NORMAN - Texas Agrilife Research; Kiniry, James

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2021
Publication Date: 5/29/2021
Citation: Chaganti, V.N., Ganjegunte, G., Niu, G., Ulery, A., Encisco, J.M., Flynn, R., Meki, N., Kiniry, J.R. 2021. Yield response of canola as a biofuel feedstock and soil quality changes under treated urban wastewater irrigation and soil amendment application. Industrial Crops and Products. 170. Article 113659. https://doi.org/10.1016/j.indcrop.2021.113659.
DOI: https://doi.org/10.1016/j.indcrop.2021.113659

Interpretive Summary: Treated urban wastewater (TWW) can be valuable for agricultural irrigation in arid west Texas, due to scarcity of freshwater (FW) supplies. However, TWW can cause soil salinization and affect soil quality and crop productivity. Therefore, crops that are salt-tolerant and less water-intensive are needed to sustain agriculture in this region. Canola (Brassica napus L.) is a biofuel crop that is salt-tolerant and requires less water than crops traditional to this area. This two–year field study evaluated performance of canola under TWW irrigation in terms of its seed yield potential and seed quality (oil content, oil yield and salt constituents), along with quantifying changes in rootzone soil salinity. Experimental design included water quality (FW and TWW) and soil amendment (gypsum + sulfur and no amendment). The TWW application did not significantly affect canola seed yields. On average, seed yields were 1975 kg ha-1. Seed oil content, oil yield and mineral constituents were also not affected by TWW irrigation. Nevertheless, average seed oil content was 42% and oil yield was 849 kg ha-1 . Gypsum and sulfur application did not influence canola seed productivity and quality. On the other hand, changes in soil salinity and sodicity were more prominent under TWW irrigation but the levels were still below the thresholds after two years. Gypsum and sulfur application reduced soil sodicity, especially in TWW irrigated soils. Thus, TWW can be successfully used to grow canola as a biofuel feedstock in this arid region while following appropriate soil management practices to alleviate sodic hazard of TWW in the long-term.

Technical Abstract: Treated urban wastewater (TWW) is seen as a potential alternative for agricultural irrigation in arid west Texas region, due to scarcity of freshwater (FW) supplies. However, TWW can potentially cause soil salinization and affect soil quality and crop productivity. Therefore, crops that are salt-tolerant and less water-intensive are needed to sustain agriculture in this region. Canola (Brassica napus L.) is a biofuel crop that is salt-tolerant and relatively less water-intensive than crops that are traditional to this area. This two–year field study evaluated the performance of canola under TWW irrigation in terms of its seed yield potential and seed quality (oil content, oil yield and salt constituents), along with quantifying changes in rootzone soil salinity and sodicity. Experimental design included a randomized block split-plot with water quality (FW and TWW) as the main-plot and soil amendment (gypsum + sulfur and no amendment) as the subplot factor. Results show that TWW application did not significantly affect canola seed yields in any of the two years. On average, seed yields were 1975 kg ha-1 across all treatments and years. Seed oil content, oil yield and mineral constituents were also not affected by TWW irrigation. Nevertheless, average seed oil content was 42% and oil yield was 849 kg ha-1. Other than the effects on soil salinity and sodicity, gypsum and sulfur application did not influence canola seed productivity and quality. On the other hand, changes in soil salinity and sodicity were more prominent under TWW irrigation but the levels were still below the thresholds after two years. Gypsum and sulfur application significantly reduced soil sodicity, especially in TWW irrigated soils. These results highlight that TWW can be successfully used to grow canola as a biofuel feedstock in this arid region while following appropriate soil management practices to alleviate sodic hazard of TWW in the long-term.