Baseline set for Cust farming couple's subsurface irrigation trial

Wet weather may have played havoc with a Cust dairy grazing couple's subsurface drip irrigation trial but they reckon they're still sorted for next season.

Gary and Penny Robinson were disappointed not to collect the data they'd hoped for from the trial due to a wet summer.

However, the couple established a baseline for the next irrigation season, which they hoped would follow a more normal weather pattern, to enable data collection.

The couple is participating in a project, examining how the next generation of farmers used innovative approaches to improve their farming practices.

Waimakariri Landcare Trust (WLT) and Waimakariri Irrigation Limited (WIL) have partnered with the Ministry for Primary Industries (MPI) for the project, with support from MPI's Sustainable Food and Fibre Futures fund along with Environment Canterbury, Ballance, and DairyNZ.

The subsurface drip irrigation system on the Robinson's two-hectare test block in Cust consisted of a network of valves, driplines, pipes, and emitters that were installed in tape below the surface of the soil.

Cust dairy grazers, Penny and Gary Robinson. Photo / Supplied

The evenly-spaced emitters slowly released water directly to the root zone of plants which differed from traditional irrigation systems that applied water to the surface of the soil.

At the beginning of autumn, the Robinsons invited agricultural services business Carrfields and farmer-owned co-operative Ballance to visit the trial block, to take pasture samples which had been used to provide a baseline for the next irrigation season.

Penny said it was great to have two key industry partners on board to provide technical assistance with the trial.

"We mowed five consistent strips of the same width and length of pasture for analysis in terms of yield and tonnage per hectare of dry matter.

This gave them a useful baseline that could be used for the following season, she said.

Having Carrfields and Ballance involved in the project was important as they were both invested in farming innovations, Penny said.

"Carrfields can see that subsurface irrigation is the future of farming and Ballance is keen to see how we can use subsurface technology to apply precise amounts of fertiliser to the root zone of plants."

Now that the couple had established their baseline figures, they planned to do an on-farm comparison between their subsurface irrigated trial block and the unirrigated section of the block.

They will also compare the subsurface drip irrigation system with the traditional sprinkler irrigation system operating in another part of their farm.

"We have learned how the system functions at a practical level and, moving forward, we are hoping for a typical irrigation season weatherwise, so we can get the data to share with potential customers and partners," Penny said.

"Having a baseline already in place allows us to track our progress throughout the season and make those important comparisons to prove the benefits of subsurface irrigation."

Penny said one of the unique benefits of subsurface drip irrigation was the precision control of the system which allowed farmers to use their water resource more efficiently, resulting in cost savings and environmental benefits.

"The exact amount of water is applied directly to the roots, which means you are not using any more water than you absolutely need to because you rely on data from your moisture probes which makes everything that much more accurate.

She said it was "irrigating to scientific data, not to what your eye can see".

"The result is overall more stable growth with better quality plants and a much better use of your water resource."

For the next irrigation season, Gary said the focus will be on measuring how much water was used by the subsurface irrigation system, the pasture growth rate and measuring how many tonnes per hectare of dry matter could be removed from the trial paddock.

"While it hasn't been an ideal season for a trial, we are hopeful that we will be able to gather the data we need next season, and we will be ready to flip the switch on the subsurface irrigation system as soon as the moisture probes indicate we need to start irrigating."