A diverse enterprise is paramount to managing the increasing effects of frost on the Hansen family’s cropping operation.
Owners: Andrew and Joanne Hansen, Garry and Merrawyn Hansen
Location: Coomandook, South Australia
Area: 8400 hectares owned and leased, 6700ha cropping
Annual average rainfall: 400 millimetres
Soil types: deep grey sand, sand over clay and limestone, red sandy loam over clay and limestone
Enterprises: cropping and livestock
Crops: wheat, canola, barley, lupins, oaten hay, barley hay
Livestock: 2000 Merino ewes (self-replacing flock), 140 Angus-cross breeders
Farming at Coomandook in South Australia’s upper south-east, brothers Andrew and Garry, their wives Joanne and Merrawyn and five employees implement several pre-season and in-season tactics to mitigate the effects of frost as best they can.
The total area affected by frost varies from year to year, from just a small percentage of the farm to some paddocks being wiped out.
“At its worst, we could have between 30 and 40 per cent production loss across our grain-growing program, which can be well over $1 million in value,” Andrew says.
Andrew says that, over the years, they have become better at identifying frost damage and puts the extent of damage down to the relationship between soil type and topography.
He believes with the advent of improved agronomic practices such as no-till farming and stubble retention, early sowing and the increasing use of nitrogen fertiliser have increased the incidence of frost, as has the recent run of dry seasons.
“It is extremely frustrating but it is something we have learned to manage,” Andrew says.
To counter the risk to their grain-growing operation, the Hansens also run haymaking and livestock enterprises.
Andrew says there are three reasons for their business’ diversity.
“We have varying soil types, including deep sands, which are unproductive for cropping, but it is also about business risk management and frost risk management,” he says.
The main tool the Hansens use to manage frost is hay and, because of that, they have all their own haymaking equipment. Andrew says this is important as they make decisions about cutting for hay in-season and ‘on the run’.
While Andrew does believe time of sowing holds some influence on frost damage, the Hansens do not use it as a major management tactic as he has still seen later-sown paddocks get frosted.
“We have a big seeding program so we might sow some of our more frost-prone areas last, but we don’t delay seeding at all because I believe that would be counterproductive,” he says.
The Hansens have found barley to be more resilient to frost damage than wheat and, over the years, have learned some things about how different wheat varieties handle frost. For example, Yitpi – which the Hansens no longer grow for several agronomic reasons – was resilient to frost, while they both found Wyalkatchem and Corack to be quite susceptible.
“Mace is our main wheat variety. It tends to be more moderate when it comes to frost, but we still grow a small amount of Corack on less frost-prone ground for its resistance to yellow leaf spot,” Andrew says.
“For our barley we grow Compass, Fleet Australia and Scope. We tend not to grow semi-dwarf varieties because if they do get frosted they don’t produce as much biomass for hay.”
Assessing the damage
In monitoring frost damage, Andrew uses a weather station based at Coomandook installed by the local Natural Resources Management board as a guide for minimum temperatures.
“We know there are certain areas of the farm that will be hit first by frost and they are the low-lying areas where cold air can be caught and held by the topography of the land,” Andrew says.
“Once we have assessed the damage we make a determination as to whether the crop is worth cutting from an economic point of view and what the crop might yield for hay versus what it might yield for grain. Hay is an extra cost – about $100 per hectare more than grain – and we have to make that judgement ‘on the run’.
“We use a target yield of 2.5 tonnes/ha for wheat and if a crop is 50 per cent frosted or more – or if it looks like it will go less than 1.25t/ha – it will be cut.”
Andrew says having all their own haymaking machinery makes the decision to cut a lot easier. They have also built some strong local markets for the hay – mainly dairy farmers, beef cattle graziers and feedlots – so there is always a home for it. In the rare case that there is not, or if some hay has too much weather damage to sell, they can feed it to their own cattle.
In 2015, the Hansens cut 300ha of frosted wheat for hay.
“I don’t think there has been one year where we have cut a grain crop for hay and I wished we hadn’t cut it – I normally wish we cut more,” Andrew says.
“I have a saying: ‘The only thing more frustrating than cutting a wheat or barley crop for hay is harvesting it only to find nothing is going in the box’.”
The Hansens have previously tried using yield mapping and variable-rate technology to manage nitrogen inputs on frost-prone areas. However, Andrew says they do not focus on that any more as he believes they are better off producing higher biomass, so that if a crop does get frosted they have more hay yield.
Cause for clay
Earlier this year the Hansens spread and incorporated clay they had raised on the property in an effort to reduce frost damage on lighter soils.
About a decade ago a contractor spread clay on some of the sandy rises around the property. Since then, Andrew has found that frost damage tends to stop where the clayed area starts.
Before seeding this year they spread clay at 75t/ha on some of the sandy hollows, primarily to try to improve the non-wetting soils, and also to reduce the effects of frost by improving the soil heatbank capacity.
Eye in the sky
Andrew believes unmanned aerial vehicles could one day be another tool for identifying frost damage.
“If a system is developed that could identify frosted areas of the farm using a camera mounted on a drone or using satellite imagery then that would be a very useful tool,” he says.
Andrew Hansen with a stack of wheaten hay cut in 2015 due to frost damage.
PHOTO: Alistair Lawson
0427 648 331,
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Clay Spreading and Delving – fact sheet
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GRDC Project Code
UA00136, CSP00180, YOU00002, CSP00143, DAW00234, DAW00241, UMU0045, CMA00002, UQ00071, CSE00198, CLT00001