grazing
Using soil sampling to improve swale design in dry coastal grazing
5 Feb 2024
When it comes to a challenge, Mark and Sharon Yensch are not ones to shy away and take the easy road. They are constantly adding to their knowledge bank of regenerative grazing principles and looking at new and innovative ways to improve their productivity, all while maintaining environmental sustainability.
Mark and Sharon had spent 15 years running an 800 hectare property situated between Stanthorpe and Warwick. Their cattle herd consisted of Murray Grey cows and Brahman bulls, the progeny of which they turned off as steers and heifers. They also produced Rhodes Grass seed and hay.
In 2007, they made the decision to start afresh and purchased 2,400 hectares just south of Bowen. The property had bare bones infrastructure, no internal fencing and little grass. It took the couple two years to completely muster all of the red and white brahman cattle that were on the property, after which they set about making major improvements. They installed laneways, built sheds, replaced the old timber yards with steel and started working on improving their herd.
The Brahman bulls were sold and replaced with Murray Greys. In response to a growing market interest in the Greyman breed, they currently turn off 60 pasture-raised bulls a year, destined for repeat buyers from the Northern Territory to Toogoolawah. Mark and Sharon find the breed to be docile and adaptable to the hard Dry Tropic region. Pictured left are some of their Greyman Bulls they've bred.
Regenerative agriculture playing a part
Sharon was invited to attend a holistic grazing workshop presented by Brian Wehlberg from Inside Outside Management and was instantly taken with the concept of regenerative grazing. Sharon started incorporating the principles she had learned into their herd and pasture management. The couple installed additional fencing and started using the grazing methods outlined in the workshop, which provided positive change in their pastures. They followed up their new learnings by attending GrazingforProfit®, ProfitProbe® and Next Steps training courses being run by RCS to improve their business management skills.
The introduction of rehydration swales
Mark had undertaken swale construction previously on a property in Tamworth and was convinced the principle could benefit their pastures in Bowen. He attended a workshop run by Geoff Lawton, Discover Permaculture, to learn the basics about rehydration swales, how they work and construction techniques. In 2016, they started construction of rehydration swales using a grader to mark the contour, followed by a dozer and scraper to do the excavation works.
The evolution of swale design
The first swales constructed on the property were 3m wide, up to 1m deep (depending on soil type), and 10m elevation spacings. The soil excavated from the swale was used to construct a raised bank on the downhill side which Mark and Sharon hand-seeded with reed and dicanthium grasses. As the water runs down the slope, it collects in the shallow swale long enough to infiltrate into the soil. This increases the effectiveness of rainfall and provides a greater reservoir of soil moisture for plant growth.
Their initial observations from the swales were that there was less runoff, the pasture plants stayed green for longer, species diversity increased and, consequently, so did biodiversity. A paddock that was initially Indian couch and snakeweed now contained over 40 different species of plants.
This year, Mark and Sharon altered the design of their swales in order to reduce maintenance associated with sediment accumulation. The new design saw the swales become narrower and deeper, with dimensions of 1-1.5m widths and 2-3m depths. This meant less soil was removed during construction, there were lower evaporation rates due to less surface area of water in the swales, and one machine could be used in their construction.
The importance of soil sampling
Mark and Sharon engaged Farmacist to undertake soil sampling as part of their pasture management. One of the samples was taken from the paddock where the new swale design had been implemented. The results indicated sodium levels high enough to limit pasture growth, which was reflected in the lack of species diversity and plant vigour noticed across the paddock.