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Water productivity on the rise (20 March 2019)

Early indications from the latest water productivity benchmark study indicate continual improvement in water use efficiency in the Australian cotton industry.

The Cotton Industry Water Productivity benchmarking team is finalising WaterTrack surveys covering the 2017-18 cotton season. They have so far covered more than 200 cotton fields, approximating to 13,000 ha, across 48 growers.

“Participant numbers are slightly up on previous surveys and give balanced representation across all major valleys,” NSW DPI’s David Perovic said.

“Early indications have identified improved water productivity compared to previous cycles. On-farm Gross Production Water Use (GPWUI) was 1.174 in 2006-07; 1.139 in 2007-08; 1.120 in 2012-13 and is tracking around 1.2 bales/ML for 2017-18.

“This trend naturally requires confirmation when all data become available and ginning data has been slower to come through from the south.”

The CRDC-supported benchmarking project is a major vehicle for collecting water-use data from across the industry to track improvement and communicating water-use efficiency more broadly.

Creating a continuous data series

Using data from seven previous published studies and other ongoing experiments and surveys, the benchmarking team can interrogate patterns stretching back 27 years, to more-accurately track the progress of water productivity across the cotton industry.

“Water productivity appears to be slowly increasing over the past 10 years, indicating the cotton industry has achieved steady improvement in yield with less water (Figure 1), but also experiences broad seasonal variation,” David said.

Meanwhile, the project has also begun supplementing survey data using other industry data sources and surveys. This allows the gaps between WaterTrack survey years to be filled to create a complete time-series for tracking the improvement in water productivity.     

“These longer time-series data indicate that the industry is achieving a steady increase in yield from less water.” David said.

“Analysis also reveals a high level of seasonal variation in water productivity and highlights the need to monitor water productivity at regular intervals and to look at longer-terms trends rather than comparing single points in time.

“Furthermore, these additional industry data allow us to examine the drivers of water productivity.”

Additional data sources: Identifying the drivers of yield and water productivity

The benchmarking team is also value-adding to data from ongoing experiments and surveys. One of these, for example, the CRDC Grower Survey, now features questions that allow calculation of GPWUI. This means that industry-wide water productivity can be monitored and benchmarked regularly in the future. These data sources also have associated management, climate data and agronomic measurement, which allow examination of the drivers of yield and water productivity. Ongoing analysis is looking into the effects of soil type, rainfall, temperatures, evapotranspiration, irrigation systems, establishment method, fertiliser rates, crop rotations and others factors in driving water productivity.

“The benchmarking team has made a number of innovations to the way they examine water productivity in the cotton industry,” NSW DPI and CottonInfo’s Ben Crawley said.

“A key component of this has been data-sharing with other industry partners.

“The project now utilises a more comprehensive time series of data, spanning 27 years, and is able to cross-valid data trends with multiple sources of data to provide more robust indications of water productivity trends, and to identify the drivers of water productivity, assisting the industry to move beyond slower incremental gains.”

Pictured above: The water productivity benchmarking team - NSW DPI’s David Perovic and NSW DPI and CottonInfo’s Ben Crawley.

Pictured below: Figure 1. Longer-term trends in cotton yield, irrigation water applied from a continuous data set spanning 1991-2018. Dotted lines indicate trend lines - increasing for yield and decreasing for irrigation.

This article appears in the Autumn 2019 edition of CRDC's Spotlight magazine.