Keeping it Green Where it Counts with VRI

Growsmart Precision VRI is one tool that may help farmers manage nutrient loss, as the ability to efficiently and effectively irrigate becomes increasingly important, Central Hawke’s Bay farmer Hugh Ritchie says.

In this weeks blog post we visit Hugh and Sharon Ritchie who operate Drumpeel Farms at Otane.  In 2014 they were winners of the Hawke’s Bay Farmer of the Year competition. Hugh was kind enough to offer his time and share with us the benefits of variable rate irrigation (VRI) at Drumpeel Farms, and the potential he sees for the technology in the future.

Hugh Ritchie says Growsmart Precision VRI is one tool that may help farmers manage nutrient loss.
(photo courtesy of Rebecca Greaves)

Drumpeel Farms comprises just over 2000 hectares of farmland between two blocks at Otane and Horonui. Cropping makes up a significant part of their operation and irrigation is key – with VRI used on both blocks. Growsmart Precision VRI has already enabled the Ritchies to eliminate overlap in their irrigation system, ensuring consistent application of water and a better return time to irrigate.

The cropping is focused at the Drumpeel block, which is 650ha. The Ritchies crop 850ha annually, with double crops. They currently have consent to irrigate 460ha and of that area, 160ha is under VRI. They have a towable pivot, a fixed pivot, a linear pivot, two hard hose with a gun and one hard hose with a boom.

Electro-magnetic mapping trials at their Wainui block, which had Growsmart Precision VRI installed by the previous owner in 2008, means there is potential to water according to soil type and depth in the future, as well as identifying leaching rates.

Soil type is an important consideration for Hugh. “Soil type is quite important and you have lower lying areas etc, so being able to manage areas is critical. We have different crops on different soil types with different water requirements,” he says.

“It’s been identified that with different soil types efficient and effective irrigation could be used to manage nutrient loss, and VRI is one of the tools that gives us the ability to do that."

“Going forward there’s a social contract that comes with the ability to utilise a public resource, like water. It’s an advantage to the farm but we have an obligation and commitment back to make sure we use that resource wisely."

“The biggest wastage of water is irrigating the driest point to wet enough, but the wetter areas get over-watered and that water goes down the drainage channels. That waste water can also flush nutrients and a badly run system can be very damaging. The concept of distribution uniformity is critical and VRI is a tool to help fine-tune that."

“It’s the invisible loss of water going to drainage because of overwatering that, in my mind, is a significant area that VRI can address. It’s going to be a very effective tool in the irrigation area to help manage nutrient loss.”

In an opinion piece published in Rural News, Waikato University agribusiness professor Jacqueline Rowarth commented on the issue of water quality, specifically the role VRI could play in maintaining water quality.

“The debate on water quality is important in the decisions about water storage and irrigation. Concerns hinge on the fear that increasing irrigation opportunities will lead to intensification in agriculture, resulting in more nutrient loss to waterways. What doesn't appear to have been considered is how irrigation water is applied on farm – yet research involving the Precision Agriculture Centre at Massey University, with researchers from Landcare, has shown that variable rate irrigation (VRI) has the potential to reduce nitrogen loss, reduce energy and water requirements, and increase production,” she said.

“VRI allows farmers to apply water only where necessary, avoiding leaching and surface runoff. Specifying type of irrigation involved in the proposed irrigation schemes could go a long way to alleviating community concerns about water quality.”

The Ritchies also installed VRI on their towable pivot three years ago, with an aim of increasing the return time. Working within their consent, VRI eliminated the overlap in their irrigation system, which has three positions, helping make the water go further.

“It (VRI) gives us ease of management. Better return times mean we can get better crops out of our soil types. VRI gives us an efficient and easy way to water." Says Ritchie
(photo courtesy of Rebecca Greaves)

“Before VRI we used to have an overlap. With VRI we were able to put bigger nozzles in the pivot and control the water flow…it meant we could get back to each place in six days, rather than losing time,” Hugh says.

“It means consistent application of water and the machines can speed up in places of overlap, which brings the return time down.”

Previously, some areas were receiving 48mls of water, areas that didn’t need it, while other areas didn’t get enough water and were too dry.

“VRI enabled a system to spread a little bit of water over a bigger area. Under our consent our water allocation is quite low, so it was about working out how to make 20 litres per second go as far as possible.”

For irrigation of large areas of land and ease of use VRI is great, Hugh says. He is also able to exclude areas from irrigation, like tracks and troughs.

“Once it’s up and running it’s a very good system and easy to follow on the menus. They have done a good job and they are still developing, which is great. They are responsive and the backup is good, but generally the product works very well.”

Growsmart Precision VRI technology was developed by Lindsay NZ (formally Precision Irrigation) and is available through Zimmatic Irrigation dealers. For more information about variable rate irrigation visit growsmartprecisionvri.co.nz or contact your local Zimmatic dealer.