Using Compost to Regenerate Soils on Large Cropping Farms
ANDREW & KARLY DUMARESQ, ‘Gregadoo’, FOREST HILL, NSW
After more than two decades of continuous cropping, Forest Hill farmers Andrew and Karly Dumaresq know they have a lot to thank their soils for.
With a rotation of wheat, canola and lupins on land with a long history of tillage, their main priority is to leave their soils better than they found them.
Moisture is one of their biggest limiting factors, and they are continually looking at new ways to help their soils retain as much moisture as possible to maximise yields.
Andrew became part of an Active Carbon Project with Australian Soil Management after attending a field day outlining how compost could regenerate soils in large-scale cropping systems.
Andrew and Karly were already exploring opportunities to use locally sourced compost products from the Wagga Shire Council’s green waste compost and a nearby feedlot.
“We were really keen to be part of the ASM project to make sure we were heading in the right direction, and to see how we could best incorporate compost into our system.”
Andrew said project results have given them the confidence to continue using compost to improve their soil health and ultimately their yields, although it will take time to fully understand changes the compost is creating.
“Compost is more of a long-term fix than short-term. Early soil tests are indicating the compost has imported more nutrients, and we can visually see a darker texture in the topsoil. It’s too early to see a significant financial benefit; we expect it will take some time for this.”
Andrew says although the project is finished, they are continuing to focus on the trial sites and will monitor further changes while exploring compost options.
He says one of the major limiting factors was the volume needed and the resources required to apply.
“For example, you need a truckload of compost versus a pallet of fertiliser – the compost is a lot more to handle and we are still in the early stages of working this out. It also takes time to put out six tonnes to the hectare. The economics of composting on a large scale are a bit challenging.”
Their property ‘Gregadoo’ is on the town fringes of Wagga Wagga. They shifted to a zero-till disc system with full stubble retention in 2010. Prior to that, they’d been transitioning towards no-till to improve soil structure, fertility and soil health in general.
“When Wagga settled this country was probably among the first that was cropped, that’s around 150 years of cropping. S
oil health across the country is going backwards due to wind erosion, water erosion and being over cultivated. I’ve been very concerned for a long time about our soil health either stagnating or not improving so am always looking for ways to rectify this.”
Andrew says they seem to be adding more and more artificial inputs yet getting the same results as they were 20 years ago.
“We have a few concerns about our soil health so everything we’re doing is focused on being able to get our soils to hold more moisture.”
They can see productivity and economic benefits to mixed farming, although a lack of stock infrastructure and labour shortages mean it is a less appealing option.
“Mixed farming is the most profitable enterprise at the moment for anyone who can do both well. I dislike sheep with a passion and I’m not wanting to go down the mixed farming route at this stage.”
Andrew knows he’s part of a generational change, and it could be 10 to 15 years before they see the full benefits of changes they are making now.
“All farmers are profit-driven and so we’re all looking at the same goal – but we have different ways of getting there. We are considering some of the principles of regenerative agriculture in our farming system, but whether we take them all on board or not, I’m not sure.
“My feeling is that there are good parts in both a more conventional system and a regenerative system. Some people go full regenerative, some go full industrial farming. We tend to sit in the middle somewhere. I believe you need to look at all options and find what works for you.”
2020 results (year 3)
Two paddocks, continuous cropping and pasture to cropping
Paddock 1: Illabo wheat crop
Where yield is lacking there are low nitrogen levels, which they can rectify by introducing a legume rotation or topping up with artificial nitrogen. They will continue to trial straight compost to determine the right balance of nitrogen to maximise yield.
Paddock 2 – pasture
The second set of trials are in a frost-prone pasture paddock where they run sheep from time to time. Their goal is to put this paddock back into cropping in the next two years.
“Visually there looks to be more pasture growth and soil fertility in the treated area is better than the non-treated area. What we are really interested in tracking is what happens when it goes back into cropping.”
“The ASM Active Carbon Farming Project is a Waste Less Recycle More initiative funded by a 'NSW EPA Organics Market Development Grant'
ASM has produced a new set of guidelines for farmers who want to build their soil quality and soil carbon stocks. If you would like a free copy, please send me an email at firstname.lastname@example.org.