In the heart of central Thailand, where the Tropical Savanna climate dictates a rhythm of wet and dry seasons, a team of researchers led by Chawanan Malee from Mahidol University’s Faculty of Environment and Resource Studies has uncovered a way to squeeze more value out of every drop of water used in sugarcane farming. Their work, published in *Agricultural Water Management*, doesn’t just tweak irrigation—it rethinks it, offering a blueprint for growers to cut water use without sacrificing yield.
Sugarcane is thirsty business. It’s a crop that guzzles water during its growth, but in regions where water is scarce or expensive, that’s a problem. Traditional full irrigation (FI) methods keep fields near field capacity, ensuring the plant never feels thirsty—but also wasting water through runoff and deep percolation. Malee’s team asked a simple but bold question: *What if we let the plant get a little thirsty sometimes?* They tested a deficit irrigation strategy, dialing back water to 50% of what the crop could use before stressing it, and measured the results in a controlled environment using two weighing lysimeters—essentially giant, high-tech scales that track exactly how much water the crop takes up.
The key to their approach was precision. They didn’t just guess at how much water the sugarcane needed; they measured it. Using the SIMDualKc model, they derived cultivar-specific basal crop coefficients (Kcb) for the commercial variety Khon Kaen 3 (KK3), a staple in Thai sugarcane cultivation. These coefficients act like a water-use ID card for the plant, telling farmers exactly how much water the crop will demand at each stage of growth. For KK3 in central Thailand, the numbers were 0.15 during the initial growth spurt, 1.11 at the peak of its hunger mid-season, and 0.49 as it matured. These aren’t arbitrary figures—they’re tailored to the plant’s genetics and the local climate, ensuring the irrigation strategy aligns with reality.
When they ran the numbers, the results were striking. The deficit irrigation strategies—particularly the moderate regimes at 25% and 50% of the maximum allowable depletion—delivered something unexpected: they slashed water use while keeping yields competitive. The rainfed system, by contrast, was a gamble, with yields swinging wildly depending on the whims of the monsoon. “We’re not just saving water,” Malee explains. “We’re making every drop work harder. That’s critical in a world where water is becoming as valuable as the energy we derive from these crops.”
For the energy sector, the implications are hard to ignore. Sugarcane isn’t just a crop; it’s a feedstock for bioethanol and a source of biomass for power generation. In regions where water scarcity threatens agricultural output, deficit irrigation could stabilize supply chains, reduce the energy footprint of irrigation (pumps, filtration, distribution), and even lower the carbon cost of growing energy crops. If water productivity improves by 20-30% without sacrificing yield, as the study suggests, the knock-on effects for renewable energy projects tied to sugarcane could be substantial. Less water means less energy spent moving it, treating it, and managing its waste—directly cutting operational costs for utilities and biofuel producers.
The research doesn’t stop at the lysimeter. Using the calibrated Kcb values, the team plugged their findings into the AquaCrop model to simulate how these strategies would play out across different scenarios. The takeaway? Deficit irrigation isn’t a one-size-fits-all fix, but it’s a tool that growers can wield with confidence. The next step, Malee suggests, is scaling up. “We’ve proven it works in controlled conditions,” she says. “Now, we need to see how it holds up in the field, across different soil types and farm sizes.”
For industries banking on sugarcane as a renewable resource, this study is a wake-up call. Water efficiency isn’t just an environmental nicety—it’s an economic lever. And as climate variability tightens its grip on global agriculture, strategies like these could mean the difference between feast and famine for both food and fuel systems. The future of irrigation, it seems, isn’t about drowning crops in abundance. It’s about listening to them—and giving them just enough to thrive.