Water use efficiency and the effective use of water in the water-abundant sugarcane agroecosystem: Which is a better measure of agricultural water use?

Authors: Ellsworth, Patrick; White, Paul

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 7/27/2020
Publication Date: 12/12/2020
Citation: Ellsworth, P.Z., White Jr, P.M. 2020. Water use efficiency and the effective use of water in the water-abundant sugarcane agroecosystem: Which is a better measure of agricultural water use? [abstract] American Geophysical Union Fall Meeting, December 1-17, 2020, New Orleans, Louisiana.

Interpretive Summary:

Technical Abstract: Understanding the relationship between agricultural productivity and water use improves the development of water budgets in agroecosystems as well as identifies water conservation strategies. Water use efficiency (WUE) is the principal measure of production relative to water use at the plant, plot, field, and agroecosystem scales. WUE is improved by reducing water use while maintaining agricultural productivity. However, using WUE as a plant breeding target or management tool to reduce water use has often proven difficult, partly because it represents a one-size-fits-all approach that does not adequately capture the complexity of the relationship between production and water use at different scales. Taking into consideration plant-accessible water availability (PAWA) in the relationship between agricultural production and water use describes the effective use of water (EUW) and can provide a better target that is adaptable to regional hydrology. In south Louisiana, sugarcane production occurs in a water-abundant region where water availability is typically high but can vary between water-limited to excessive across years. To better understand the EUW, we compared WUE (yield per unit of evapotranspiration) to yield relative to PAWA. Water available for sugarcane transpiration exceeds its water use; therefore, increasing production can occur potentially through increasing photosynthetic water loss (transpiration). Plant traits such as rooting depth can increase PAWA across the range of soil water availability and increase aboveground growth and yield. Thus, increasing EUW in sugarcane can increase yield while effectively and sustainably using available water, even though WUE may not change.