Growth Measurements

The Burdekin Precision to Decision (P2D) project has been working with growers to maximise the effectiveness of their irrigation scheduling tools via daily crop growth measurements over one (or preferably two) irrigation cycles.

P2D grower Jimmy Hayllor purchased his farm in the Clare area nearly three years ago. Jimmy saw the need to gain a better understanding of the sugarcane growth patterns in response to irrigation in order to maximise crop growth. He then conducted growth measurements with support from Senior Agronomist Heidi Hatch Gordon.

Monitoring growth patterns involved measuring the same 20-25 sticks, at the same time everyday, so that peak daily growth rates could be determined. During ideal growing conditions, sugarcane crops can reach a maximum daily growth rate of 45-50mm!

However, as the soil begins to dry and the crop expends more energy into extracting water than producing biomass, the daily growth rate begins to slow (as seen in the graph). When the average daily growth reduces to 50% of the maximum peak growth for two consecutive days – this is deemed your irrigation trigger point. This point can then be correlated to the number of dots displayed on your G-Dot moisture probe or, as in Jimmy’s case, the total millimetres removed from the mini-pans.

This data can then be compared to solar radiation and evapotranspiration. The analysis of the data aids in making decisions of when to irrigate to maximise growth over the peak growing period.

The original work by Gary Ham, Evan Shannon, and the BSES team in the mid-1990s, stated that improvements in irrigation scheduling with mini-pans resulted in 10% yield improvements on some farms, and water savings of up to 10-47% in others (Shannon & Raine 1996).

Jimmy has been working closely with P2D project manager Heidi Hatch Gordon and Principal Agronomist Evan Shannon from the Burdekin Farmacist office to build a better understanding ofhis farm through EM mapping, targeted top and subsoil samples, mung bean yield mapping, satellite imagery and irrigation water samples to maximise his sugar yield.

The data sets have also enabled Jimmy to make more informed chemical decisions and appropriate pre-emergent chemical choices through the Bluewater 2 project.

Reference: Shannon, E. L., & Raine, S. R. (1996, January). Improving the irrigation efficiency of Burdekin canegrowers. In Proceedings of the 8th Australian Agronomy Conference (pp. 502-506).

Precision to Decision is funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation, and Farmacist.