IT has been a constant frustration for Werneth farmers Evan and Suzanne Lewis that in spite of good annual rainfall and generally soft finishes, crops that were underwater in August could end up moisture-stressed in the spring.
“Soil constraints are our biggest issue, we have some heavy, sodic soils with very poor water holding capacity,” Mr Lewis said of his farm, roughly located between Geelong, Ballarat and Colac in Victoria.
“There is a hard pan sometimes less than 300 millimetres down and the plants just don’t seem to punch their roots through.”
Mr Lewis said this meant the worst of both worlds for the crop.
“Rainfall does not soak in that well, so you get pooling and waterlogging through the winter and then in the spring you need rain constantly or it can dry out.”
He said this heavy soil type was prevalent on the home block, but on other parts of the farm there were loamier patches.
“You can see the roots push down better.”
With this mind, the Lewises have made improving soil structure a key priority.
Initially, the focus was on no-till farming and controlled traffic and now the emphasis is on more advanced techniques such as summer cover cropping.
Mr Lewis said increasing organic carbon levels was a major goal.
“If the carbon levels are up, the soil structure and micro-organic activity is also up.”
Benefits of controlled traffic
The Lewises have been using controlled traffic for eight years, and Mr Lewis believes the soils are now starting to show the benefit.
“They are really starting to come into their own now.
“You can really tell the difference between the compacted tram lines and the rest of the paddock which is now much loamier.”
The controlled traffic system, on 30-centimetre spacings, using primarily an Excel disc seeder with a Simplicity cart, also allows for inter-row sowing. It is based on three-metre centres, including a nine-metre header front.
“This year we’ve had some trials planting some summer brassicas in between a late barley crop.
“The brassicas emerged alright, but it appears they haven’t handled the competition that well, but in terms of getting the crop planted inter-row, it was easy.”
Interestingly, while the Lewises are committed no-tillers they are happy to incorporate livestock into their enterprise, with Suzanne managing a flock of 600 composite ewes that this year dropped 800 lambs.
“You hear that livestock are a no-no in no-till systems and that they cause soil compaction, but our research suggests that’s not the case,” Mr Lewis said.
Working around slugs
The Lewises crop around 1000 hectares, with wheat and faba beans two key parts of the rotation.
Mr Lewis said canola was formerly a very important crop, but slug pressure meant he had left it out altogether this year.
“The slugs have really made it very difficult to grow canola here, I was due to have a small plant this year due to the rotation and I ended up just leaving it out altogether.
“In terms of broadleaf crops, the faba beans cope much better with slugs.”
Growing faba beans is still something of a novelty in the Western District, where generally acidic soils and the propensity to waterlogging mean pulse crops can struggle.
However, Mr Lewis said beans, which cope with both low pH soils and the wet better than the other major legume crops, had been very good, not only as a break crop, putting down valuable plant available nitrogen, but as an excellent cash crop.
“In good years you can get over four tonnes a hectare and with prices above $400 a tonne you can get some good returns.
“(Beans) are also really good at fixing nitrogen, providing they are inoculated and with the increased level of microbial activity, we are seeing the crop residue just melt away which is good for the soil structure.
“There is also the disease break for the cereals in having a pulse phase.”
With time of sowing is sneaking ever forward, Mr Lewis said the early sown crops have had a clear advantage in most years.
“The beans went in this year around Anzac Day and the wheat was planted in early May.”
Annual ryegrass is the major problem weed, but after a disciplined campaign to cut seed numbers, Mr Lewis feels he is getting some traction.
“This year, the paddocks have been the cleanest they have been for a long time.”
He said the ability to desiccate crops was critical in lowering ryegrass seed numbers.
“In this milder environment, it is nothing to get a germination of ryegrass in October which can cause problems.
“The problem is getting more pronounced as with our herbicide programs, we’re actually selecting for late germinating ryegrass.
“Desiccating is a good way of cleaning up those late germinating plants.”
In terms of cost of production, Mr Lewis said as befitting a higher yield environment, costs were higher than in other parts of the State.
“We put out a reasonable amount of inputs, and that includes a strong trace elements program, things such as copper and zinc.”
The couple generally attempt to grow milling wheat.
“We have had some long-season red wheat in this year, but it hasn’t gone that well, I think we will stick with our milling lines which have gone well.”
Looking for the right mix
Mr Lewis is hopeful summer cover crops can play a key role in opening up his farm’s hostile subsoils.
He is experimenting with the concept after hearing presentations from American soil health experts Jay Fuhrer and Jill Clapperton at Victorian No Till Farmers Association conferences.
“They’ve had some great results in places like North Dakota with a cover crop that is a mixture of broadleaf and grass species.”
Mr Lewis said he had been tempted to deep rip at the start of the cropping phase to open the soil up, but said Dr Clapperton advised a low disturbance method utilising plants.
With this in mind, he has put in a mix of ryecorn, a cereal plant, forage rape, daikon radish, clover, vetch and oats to provide cover over summer.
He said the system was designed to renovate the paddock with plant roots creating a more permeable soil with better water holding capacity.
The major issue will be getting the crops to establish over summer.
“Maybe it won’t be something we can do every year as they can in the States, but if it is going to work anywhere in Australia it is in our higher rainfall zone with cooler summers.”
Mr Lewis said he had seen what sunflower crops had done in terms of boosting the following winter crop and believed the concept of a summer cover crop was sound.
“They put their roots down and create channels for the following winter crop to push down into.”
“We haven’t been able to make sunflowers stack up economically, but we’re busy trialling various combinations to see if we can come up with one that works.”
This year, Mr Lewis is experimenting with spring-sown cover crops inter-rowed in between winter crops, but he says it will be reliant on rainfall after a dry spring.
Another key plank of improving soil structure is a big gypsum and liming regime.
“We’ve put on up to six tonnes per hectare of gypsum on the heavy soil and it has been really beneficial.”
He said he was measuring his soil health by improvements in organic carbon levels.
“We’re at around 2 per cent carbon now, I’d like to see us pushing up to three per cent.”