From the surface, Tony and Sue Reynolds’ 80-hectare dairy farm at Burnham, south of Christchurch, looked straightforward. Their two irrigated blocks sat side by side on Lismore soils, both served by lateral applicators and both appearing almost identical. But when Tony wanted a clearer picture of what was happening beneath the surface, the results were anything but the same.
Already a Water to Grow customer, Tony was using the platform to monitor water use, storage and effluent applications across the farm. With an existing LoRaWAN gateway providing network coverage, it was easy to add more sensors without requiring separate telemetry on each device.
Water to Grow installed two EnviroPro probes, one in each block. EnviroPro is one of the most popular soil probes used in New Zealand, valued for its reliability and ability to measure both temperature and soil moisture using four sensors at depths of 10cm, 20cm, 30cm, and 40cm. The data is simply connected through the Water to Grow app, giving farmers a clear view of soil conditions in real time.
What the probes revealed surprised Tony. While the top 10cm of both blocks looked similar, the deeper soil layers told a different story. The north block consistently held far more moisture than the south block, with differences of up to 20% by late June at 30cm depth.
To investigate further, Water to Grow Field Engineer Paris Molver worked with EnviroPro to test the soil directly. Laboratory drying confirmed the probe readings, showing the north block had 13% higher gravimetric soil moisture. The answer became clear after the soil was sieved: the south block contained twice as much rock, making up 10% of the sample compared with 5% in the north block.
That extra rock reduced the soil’s ability to store water, meaning the south block would dry out faster and likely require more frequent irrigation to support pasture growth.
The lesson is simple: paddocks that look the same on the surface can behave very differently below ground. Soil monitoring gives farmers the evidence they need to make better irrigation decisions, improve pasture performance and use water more efficiently.
How Soil Monitoring Solved an Irrigation Mystery
Canterbury Dairy Farm sees Immediate Benefits from Water to Grow’s Soil Monitoring Solution
At first glance, there was no obvious difference.
Tony and Sue Reynolds' 80-hectare dairy farm near Burnham has two irrigated paddocks sitting side by side. They share the same Lismore soils, are irrigated using similar lateral systems and, from the surface, look almost identical.
Yet they weren't behaving the same.
Already using the Water to Grow platform to monitor irrigation, water storage and effluent, Tony wanted a better understanding of what was happening beneath the surface. Adding two EnviroPro soil moisture probes to the existing Water to Grow network was straightforward thanks to the farm’s existing Water to Grow LoRaWAN gateway.
Looking below the surface
Initially, the results seemed normal.
At 100 mm depth, both paddocks showed very similar soil moisture levels. But as the probes looked deeper into the soil profile, a different picture emerged.
At 200 mm, 300 mm and 400 mm depths, one paddock consistently held significantly more moisture than the other. By late June, the difference at 300 mm depth had grown to around 20%.
The question was obvious.
Why?
Finding the answer
Rather than guessing, Water to Grow worked with EnviroPro to investigate further.
Soil samples from both paddocks were dried and analysed in the laboratory. The results confirmed what the probes had been reporting all along.
The "wetter" paddock contained around 13% more soil moisture.
The reason became clear once the soil was sieved.
One paddock contained roughly twice as much rock as the other. The extra stones reduced the amount of soil available to hold water, meaning that paddock simply couldn't store as much moisture and would dry out more quickly.
"I never expected two neighbouring paddocks to behave so differently."
-Tony Reynolds
Better information leads to better decisions
Without soil monitoring, both paddocks appeared almost identical and would likely have been irrigated the same way.
The data showed they shouldn't be.
Understanding how much water is actually available in the root zone allows irrigation to be matched to each paddock's needs, improving pasture performance while avoiding unnecessary irrigation.
Sometimes the biggest differences on a farm are the ones you can't see.
Want to understand what's happening below the surface on your farm? Talk to Water to Grow about integrating soil moisture monitoring into your irrigation system.
