Row spacing and the use of plant-available water in sugarcane cultivation in water-abundant Louisiana

Authors: Ellsworth, Patrick; White, Paul

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2022
Publication Date: 6/30/2022
Citation: Ellsworth, P.Z., White Jr, P.M. 2022. Row spacing and the use of plant-available water in sugarcane cultivation in water-abundant Louisiana. Agronomy. 12(7):1586. https://doi.org/10.3390/agronomy12071586.
DOI: https://doi.org/10.3390/agronomy12071586

Interpretive Summary: Row spacing needs to be optimized to improve yield by taking advantage of resources such as light and water. Sugarcane in Louisiana is principally grown on rows spaced 1.8 m apart, but interest in 2.4 m row spacing has grown. In this study the effect of row spacing on water availability was studied. Soil moisture at 15, 30, and 45 cm depths was monitored from 2017 to 2020 in plots with 1.8 and 2.4 m row spacings and two varieties (L 01-299 and HoCP 04-838). Soil water content was slightly greater on average in 2.4 m than 1.8 m row spacing at 15 and 45 cm, but the biggest difference was that when water was most limiting, much more water was still available in 2.4 m rows than 1.8 m rows. However, in either row spacing plenty of plant-available water was always present in the top 45 cm, even during periods of little rain. Consistently abundant and available water could provide an opportunity to increase increase photosynthesis in sugarcane varieties by increasing stomatal conductance (water loss).

Technical Abstract: Purpose: Optimizing row spacing can potentially improve yields when resources such as light and water are limited. Sugarcane in Louisiana is principally grown on rows spaced 1.8 m apart, but interest in planting on 2.4 m rows is increasing. In this study the effect of row spacing on water availability was studied. Methods: Soil moisture sensors were placed at 15, 30, and 45 cm depths in a split-plot design with three plots of each treatment combination. Treatments included: 1.8 and 2.4 m row spacings, two varieties (L 01-299 and HoCP 04-838), and two planting dates. Soil moisture was monitored in 15-minute intervals from 2017 to 2020. Results: Volumetric water content was slightly greater on average in 2.4 m than 1.8 m row spacing at 15 and 45 cm, but the biggest difference was observed when soil water content reached its lowest levels where the 2.4 m rows had 1.1, 3.1, and 9.8 times more water available at 15, 30, and 45 cm, respectively, compared to the 1.8m row spacing. However, in both row spacings plant-available water was always present in the top 45 cm, even during periods of low rainfall. Conclusion: The wider row spacing provides more water for transpiration, but overall water availability was high to excess. Potentially, high water availability provides an opportunity to increase photosynthesis in sugarcane varieties by increasing CO2 uptake through greater stomatal conductance.