CONSERVING water on his property is a priority for North Dinninup farmer Hugh 'Jock' Rogers.
To help conserve more water and improve the degradation of his land, in April 2019 he established a 3.4 kilometre system of interceptor banks, comprising five separate banks.
After observing the results from two seasons, Mr Rogers said he was pleased with the difference but it would take several more years to see even more benefits.
"The long-term benefits are what I'm chasing - I think I'll see more results in the next four years and I expect there to be a big change in the productivity of the land," Mr Rogers said.
He has been involved with the Whittington Interceptor Sustainable Agriculture Land Treatment Society (WISALTS) for many years and consulted the group's president Jim Sorgiovanni to establish the interceptor banks.
The Whittington Interceptor Bank surface and subsurface water management system is designed to control surface and subsurface water flow on the catchment.
WISALTS states that these flows account for up to 85 per cent of the water; with only 15pc water flow on a catchment being deep groundwater.
The system prevents water moving downslope taking with it humus, organic material, phosphate (from fertiliser), soluble salt and other nutrients necessary for plant growth.
Once the system dries out the valleys, nature can begin the reclamation, aided by oxygen and aerobic soil macro and micro flora.
Mr Rogers' property had duplex sand over clay, laterite and some granite soil types and natural vegetation included wandoo, jarrah, redgum/marri, rivergum, marlock, grasstree, tea-tree, banksia and snottygobble.
The property's rainfall had declined since the 1970s, with a long-term annual average of 675 millimetres.
In 2019 only 415mm was recorded, the lowest rainfall on the farm since the 1960s.
The property has been operated as a mixed cattle, sheep and more recently cropping farm.
Mr Rogers had observed that land degradation was evident on the oldest land cleared and deterioration was more obvious with saline type barley grass since the 1970s, as well as the presence of crassula, cotula and toad rush (water weeds), dying trees and bare ground.
Water tests conducted by Mr Sorgiovanni from 36 metres of depth found groundwater to be saltier than sea water and no freshwater streams.
The bank was then ripped by a bulldozer.
An excavator was used to dig a trench to a maximum depth of 9m and average depth of 2.85m.
The banks were lined with 200 micron builders film and then backfilled by a dozer.
Five days were allocated to establish the system.
Rainfall in that first season with the banks was 275mm below average.
"Observation wise where water used to hang around, there was nothing there, so 2019 wasn't really a good year to test the banks," Mr Rogers said.
Although 2020 was also a below-average rainfall, it wasn't to the same extent as the previous year.
"This past year we had a reasonable season and it was a lot better for reduced water logging," he said.
"WISALTS has always said that it takes several years to claw back damaged areas, so for those areas that are bare ground, it might take a number of years to see results."
Prior to the banks being in place, the crop yields in the area were not covering costs, so Mr Rogers changed the land use to pasture.
Previous yields in the affected area were 0.5 tonne per hectare for canola, 0.8t/ha for oats, 1.5t/ha for barley.
Ongoing frost and significant water logging were key constrictors for canola and oats.
In 2020, the area was cropped to oats and saw a major improvement, yielding 2.74t/ha.
The grain also achieved premium quality, going Oat 1.
Water weeds and grasses such as ryegrass, brome and silver grass were still a significant issue, however to a lesser extent.
Mr Rogers reported a "dramatic improvement during the wet months of trafficability for seeding and follow-up fertiliser spreading".
He said areas which were formerly too boggy to sustain a crop and non trafficable grew a crop which was harvested last month.
Areas of bare ground hadn't increased and low lying country showed improvement.
"I plan to implement these banks on other areas of my property," Mr Rogers said.
"I'm a conservationist at heart, I want to give back to the land and don't want to see the degradation that comes with clearing - I have a lot of natural timber on my property that I will retain.
"We are looking to achieve more efficiency per millimetre of rainfall."
