Ecosystem-level water use efficiency and evapotranspiration partitioning in conventional till and no-till rainfed canola

Accurately determining productive water use ( i.e. , transpiration T, component of evapotranspiration ET) is crucial to improve ecosystem efficiency (EWUE) and develop water-saving management practices. High frequency (10 Hz) eddy covariance data for the 2016–2017 growing season (November 2016 – May 2017) conventional till (CT) no-till (NT) canola Brassica napus L.) fields were analyzed partition ET into T evaporation (E) using Flux Variance Similarity method. The objectives this study determine compare seasonality T/ET ratios, EWUE based on different metrics carbon (gross primary production, GPP net production NEP) vapor (ET T) fluxes in CT NT fields. Canopy stands, fluxes, similar until winter both fields, but substantially lower field from February April due differences recovery stands after dormancy. However, much smaller loss than gain. Larger difference was observed significant amounts E during rainy periods under dense (CT field) sparse (NT canopies. average ratio identical (~0.70) ~23% higher ~26% a dry period peak growth. In comparison, ~36% ~58% wet growth relatively soil canopy. results not only illustrated discrepancies cross-site comparisons also highlighted added value estimates over more meaningful E. • Partitioned (ET) Determined GPP, NEP, ET, T. Transpiration (T) accounted ~70% total season. caused large comparisons. Results bulk estimates.