Sunflowers were part of a multi species summer cover cropping project at Rupanyup in Victoria.

Wimmera croppers covering all bases

With searing temperatures the Wimmera in Victoria might not seem the place for summer cover crops - but farmers are happy with trials.

WIMMERA farmers experimenting with mixed species summer crops are confident the concept will improve soil health over the long time.

Ben Cordes, agronomist with Tylers’ Rural Supplies in Rupanyup, said a couple of his clients had experimented with warm season multi species cover crops as a means of soil amelioration – and the early results are promising.

Mr Cordes said warm season cover cropping had gained a foothold in southern Australia in recent years, but had previously been limited to higher rainfall zones.

“It’s all about experimenting with the concept of regenerative agriculture in our area,” Mr Cordes said.

“Initially we thought the Wimmera climate may have been unsuitable, however the cover crops have held on really well given the dry and hot summer,” he said.

Mr Cordes said the paddocks were planted with a mixture of warm season broadleaf, legume and grass species.

The major idea behind the cover crop is to improve soil quality and achieve a more resilient farming system for the future, but there have been some counterintuitive discoveries.

“Historically we’ve been clearly shown the benefits of minimizing summer weeds to conserve soil moisture,” he said.

“However, in this situation there may well be a positive response from green plants providing enough shade and cooler soil temperatures to significantly reduce soil water evaporation.” 

The cover crops were planted with the larger seeds going in one of the seeding boxes and the smaller seeds through a small seed box in one pass.

“It probably wasn’t the most sophisticated system but we got it planted and it all came up alright.”

The summer cover crop keeps soil temperatures down.

Paul Oxbrow, Rupanyup, is one of the growers planting multi species cover crops.

Within the mix he has included winter canola.

The idea will be that the summer species either die or are sprayed out in autumn and the winter canola is allowed to continue to grow with a view to harvest in November.

“Some rain would be nice but at present the canola is still hanging on,” Mr Oxbrow said.

Mr Oxbrow, a former president of the Victorian No Till Farmers Association (VNTFA) said he was inspired to experiment with the cover crops after hearing a number of international presenters at VNTFA events.

“It’s all about improving soil biology – I think we have to look outside conventional farming systems here, we are already seeing less efficacy from synthetic fertilisers like urea so this is one way we can work to improve overall soil fertility.”

“It goes a bit against the way we have been taught to farm in recent years, to keep as little alive over summer as possible to preserve moisture, but the international data shows that having living species and living root systems on the paddock as long as possible can really help with fertility.”

Mr Oxbrow also said the ability to keep soil cool was a key driver in planting the crop.

The outcome so far has been pleasing.

Mr Cordes said he had taken temperature samples on a 44 degree day.

In the area with residue and warm season cover crops temperatures were up to 20 degrees cooler than the control strip left as a bare chemical fallow.

Mr Cordes said the data from the trials was remarkable.

“The results really were astonishing, it was certainly an eye opener and at the same time concerning to know how hot our soils can get in the middle of summer” he said.

Mr Oxbrow said it had been interesting to see how early the difference in soil temperatures had become apparent.

“Even in October, when the temperature was only around 20 you saw the area with soil cover was markedly cooler.”

He said given the climate, he felt summer crops would be planted opportunistically in the Wimmera.

“You need the moisture to get them up, but when you can get them germinated alright the mix seems quite hardy.”

“The paddock is hardly going gangbusters, but that is not surprising given how many days above 40 we have had in January, and plants are still alive.”

Mr Oxbrow said he felt the project would need between three and five years to start showing clear benefits.

“It is definitely something for the long-term.”

In terms of monetary gains from the crop, the canola will be harvested and the paddock grazed with sheep.

“We have not been big into sheep so this is a bit of a change.”

He said he would experiment with temporary electric fencing to try and get the paddock grazed evenly.

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