Mega trenches help farmers in the fight against salinity

Farmers are finding favour in the fight against salinity by digging enormous trenches in a bid to save the State’s bread basket.

Salinity is one of the biggest environmental issues for Australia, and has been part of the WA landscape for decades.

More than one million hectares of previously-productive land in the State’s South West Land Division has been severely affected by dryland salinity.

About 750,000ha has been moderately affected and up to 4.5 million hectares is at risk.

Salinity damage is estimated to cost $519 million in lost agricultural productivity per year.

Narembeen farmer John Hall said carving rough channels up to three metres deep throughout his farm has enabled him to drain millions of litres of water and hundreds of tonnes of salt to reclaim land for crops, trees and pasture.

He now has one of the State’s biggest rough channel systems on the broad, flat valleys of the north-eastern Wheatbelt.

“If I said I told you I can make salt lakes grow grass, you could wonder what I was smoking,” Mr Hall laughed.

“But I have seen the bigger picture and I see that where you dig these drains, you can control water flow.

“There are parts of our farm that salty since i was a kid... and we applied some of these techniques and have had amazing results.

“More farmers should be doing it.”

Mr Hall said he was motivated to test the drainage system about 25 years ago as a way to mitigate flood damage and salinity.

He dug about 35km of drainage on his farm across three or four years while contracting to other farmers.

“When you get a big event or flood, we used to get a lot of damage to paddocks,” he said.

“But there is a lot you can do to design it to hold water back and to flow gradually.

“Narembeen doesn’t get flooded now, because we have these drains ”

Dozens of farmers have adopted the revegetation design system during the past decade, and Mr Hall says land once barren in his area were growing productive crops and pastures within a year of the channels being dug.

“One of my neighbours had a paddock that wasn’t cropped for 30 years, the next year after I dug a drain, he cropped nearly all of it,” Mr Hall said.

“We have brought thousands of hectares back to production, and stopped the town of Narembeen from flooding.”

Behind the digger is 73-year-old John McKay, a Tasmanian-born man involved in earthworks, mining and farming for most of his life.

He is one of the contractors specialising in digging large drainage systems in the WA Wheatbelt.

After growing up at Woodbridge, south of Hobart, he left the family farm at the age of 15 to work for his parents’ neighbours.

He travelled around Australia as a young man before finding his feet in drainage 24 years ago.

He first started working for Mr Hall, and then started contracting to other farmers.

One of those was well-known John Nicoletti, who is widely regarded as WA’s richest farmer, about 20 years ago.

“Farmers are finding that this worked and are willing to give it a try,” he said.

A Department of Primary Industries and Regional Development spokeswoman said landholders planning earthworks to manage salinity were required to lodge a Notice of Intent to Drain with the Commissioner of Soil and Land Conservation before proceeding.

Failure to notify the Commissioner or commencing works before receiving a letter of no objection may result in a fine, while works resulting in land or water degradation could lead to a Soil Conservation Notice.

“Under Soil and Land Conservation Regulations (1992), a Notice of Intent form is to be submitted at least 90 days before draining commences,” she said.

A DPIRD officer will undertake a site inspection and discuss the proposal with the landholder to identify any potential land degradation risks.

Commissioner Cec McConnell said each proposal was unique and it was important to work collaboratively to mitigate and prevent land degradation.

“Drainage can impact neighbouring properties so it is best practice to consider any earthworks as part of an integrated catchment management framework,” she said.

“The Notice of Intent provides a mechanism to examine a full suite of options for managing groundwater to identify potential degradation and land management strategies to reduce any environmental risks.

“Notification also gives neighbouring landholders and public authorities the opportunity to comment on the drainage proposal.”

To find out more, about guidelines and investigations that should be undertaken before designing a groundwater drainage system, visit agric.wa.gov.au/water-management/deep-drainage-groundwater-drains-salinity-management-western-australia

This includes site assessment, design and construction guidelines; working with contractors.