A lot of time, money and effort can be pumped into a crop during the growing season to try and attain maximum yields, only to be spoilt by a frost. However, there are things you can do to manage the risk if you’re in frost-prone areas. One approach is dividing up your farm and even paddocks into frost zones so that you can plan strategically around them.

So, what are Frost Zones?

Your frost zones will consist of red, amber, and green zones. 

Green zones represent areas with no risk of being frosted and where your best, high-yielding varieties can be sown. This is where you want to apply optimum inputs to achieve high yields. These zones have never been frosted and never will be frosted. 

In contrast, red zones represent substantial risk areas of your farm where sowing times, varieties, and inputs must be carefully managed to try and avoid frost damage to crops during critical growth stages. The red zones are the areas where frost is regular or severe. For instance, where it is normal to get frosted at least 7 out of 10 years. 

The amber zones are those which may or may not be frosted, depending on the severity. For example, a severe frost may extend beyond a red zone into an amber zone, but will never reach a green zone. 

How to Implement Frost Zones:

There’s a good chance you are already doing this on a full farm scale. Obviously, understanding the topography of your farm and knowing it’s history plays a crucial role in determining frost risk areas. As you know, low lying areas are more prone to frost due to cool air draining down slopes. Paddocks situated on higher ground, subject to sea breezes or exposed to warmer temperatures, are at a much lower risk of frost damage. 

Topography is often highly variable across a farm, but it can also be highly variable within a paddock, such as in sloping or dune-swale scenarios. In paddocks like these, we can also aim to rezone red, green and amber boundaries and implement strategic farming that can provide significant benefits by managing frost risk.

How To Frost Zoning Paddocks:

First, you need to know the risk for each paddock in order to know what strategies to apply. You need to assess paddock by paddock and be familiar with the historical risk of each.

Let’s say you have a paddock you want to put into wheat that contains all three zones. When you divide it up and map out each zone, you can then go ahead and strategically plan for each risk zone. 

For instance, you may opt to roll the red and amber zones so that you have the option to cut for hay should it be frosted. If possible, you could consider grazing the red zones during the vegetative phase – which will help delay maturity and hopefully push back flowering so that it occurs after the main frost risk period. (In this situation, it can pay to be mindful of using chemicals that have long grazing or cutting withholding periods). 

Another method could be reducing the previous season’s stubble load in the red and amber zones by slashing or speed tilling to help reduce frost risk. And in contrast, leaving more stubble is ideal in the green zones. As you know, high stubble loads reflect radiation from the sun, meaning the earth beneath the crop warms less, allowing for more rapid cooling at night.

Another tactic you might opt for is planting different wheat varieties in the different zones. Certain varieties can be more suited to cutting for hay or later maturity. These could be put in red zones, whereas you would opt for the best-performing high yield varieties in green zones. 

Another essential adjustment to make is optimising inputs. For instance, you can aim to reduce nitrogen rates in the red zones. This will not only save costs but also help reduce stubble loads and canopy density, which in turn will help reduce frost damage. Then that nitrogen reduced from the Red Zones could then be moved on to Green Zones to really maximise production in those areas.

The key point is to change your planning outlook – instead of planning around your paddocks, plan around your frost zones. That way, you can implement strategies to mitigate the risk of frost. Taking the time to consider appropriate crops, varieties, sowing times, and inputs can pay off. Remember, you can’t manage frost damage, but you can manage your vulnerability.

In summary:

Red Zones:

• Look at crop types that are the least susceptible, such as pastures, hay, oats, beans and barley.
• Grow dual purpose crops (grain and graze, or hay and grain).
• Grow awnless wheat/barley varieties.
• Consider minimising inputs and using the extra in green zones.
• Consider grazing crops – to help delay flowering time.
• Review stubble management practices.
• Consider rolling, so the option to cut for hay is available.
• Sow beans early.

Amber Zones:

• Consider rolling so the option to cut for hay is available.
• Look at crop types that are the least susceptible, such as pastures, hay, oats, beans and barley.
• Consider grazing crops – to help delay flowering time.
• Review stubble management practices.
• Look at different varieties that may have longer-maturity.

Green Zones: 

• Optimise inputs.
• Grow your best, highest-yielding varieties.
• Retain more stubble.

Example below:

Frost Zoning Whole Farm – Paddock by Paddock

You are probably aware of what strategies to undertake on a whole farm scale. But using the Red, Amber and Green zoning areas on a full farm scale can also be helpful if it is too hard to split individual paddocks. The same strategies from above can be implemented in paddocks. And it is also crucial to consider the maturity times of varieties and adjust sowing times so that crops are flowering over a longer period – so that if a severe frost occurs, it may knock out some crops during flowering rather than all of them.

Give one of our agronomists a call if you’d like to know more or need help identifying which areas on your farm are potential frost risks.

We want to thank independent agronomist Mick Faulkner for his work in this area and the development of frost zoning strategies in the Mid North.