ISSUE 3 Better Frost Decisions

ISSUE | DECEMBER 2021

BETTER FROST DECISIONS Knowledge to inform grower and adviser decisions for pre-season planning, in-season management and post-frost event responses

IN THIS ISSUE How cold did it get in Spring?

Regional frost update Did we make Better Frost Decisions ? podcast.

Frosted barley crop Mallee

Were you impacted by frost in 2021?

In this issue we reflect back on the season that was with frost events. With a late start to the season we were hopeful that with later emergence crops would have matured later in the season and may have avoided flowering in the frost window.

However, as growers have started harvesting crops the extent of frost damage is becoming clearer. Growers are reporting that frost damage has impacted on yields to varying extent across the region.

The SARDI Climate Applications group have reviewed the BoM data compared to temperature logger data taken from paddocks across the demonstration sites to try and uncover the real frequency of frost events in the field and when low temperatures likely caused the most damage.

So what happened with minimum temperatures in Spring?

The maps from BoM show the widespread cold temperatures and the slow moving high pressure systems interspersed with cold fronts. Frosts tend to occur when the high pressure system moves in after a cold front.

The impact of frost on each crop is different depending on the position of the paddock and the stage of crop development. For most of southern Australia the optimum flowering window is in September, hence early October frosts can be damaging and leave limited time for recovery.

Continued....

WELCOME In our third and final issue for the year we take a look at the frost temperature data collected in Spring and compare this to BoM sites. How big is the difference between the two?

We chat to the groups to find out how their demonstration sites handled a frosty October.

For this issue we also chat directly with the Frost Extension project team to bring you a podcast version of the newsletter for easy listening while harvesting.

Our regular contributors are Peter Hayman and the team from SARDI Climate Applications and farming systems groups AIR EP, UNFS, MSF, BCG and SFS. Next issue out in March 2022.

A frosty October 2021.

Across much of southern Australia there were a series of frosts starting on the October long weekend.

Minimum Temp 5th October 2021

Minimum Temp 8th October 2021

Minimum Temp 11th October 2021

Source: Bureau of Meteorology

Minimum Temp 6th October 2021

Minimum Temp 7th October 2021

Minimum Temp 9th October 2021

Minimum Temp 10th October 2021

Minimum Temp 12th October 2021

Minimum Temp 13th October 2021

Measuring temperature at crop head height During the 2021 season, data loggers were placed in wheat paddocks by participating farming system groups.

Early in the project, the farming system groups agreed to a standard approach to measuring the temperature with an exposed TinyTag data logger which was moved to be at the height of the wheat head in the field.This information was provided by Kelly Angel from the Birchip Cropping Group based on her experience with the GRDC National Frost Initiative.

The standardised measurement for frost experiments is an exposed data logger at crop head height whereas the standard for the Bureau of Meteorology is a screened data logger at 1.2 m above the ground.

The obvious reason for using a screened data logger is to shade the logger from the sun so that the measurement reflects air temperature and not the logger heating up from being exposed to the sun.

To get a better handle on the difference between the nearest BoM station and the field sites, SARDI Climate Applications provided extra data loggers to be installed in the trial sites at 1.2 m.

Data (right) shows daily maximum and minimum temperatures in the wheat paddocks at Murray Town in the Upper North of SA, Parrakie and Paruna in the SA Murray Mallee and Tooligie on the Eyre Peninsula. Each figure shows the comparison with daily maximum or minimum temperature recorded at a nearby Bureau of Meteorology station.

Temp logger at crop height.

The yellow tiny tag gets moved up as crop height increases

As expected, there is a much closer relationship between the field sites and the BoM station for daily maximum temperature than daily minimum temperature.

The relationship for minimum temperature is greater in the Murray Mallee (Paruna and Parrakie) than the Upper North (Murray Town) and Eyre Peninsula (Tooligie).

A general rule of thumb is that the canopy is about 2.2 °C colder than what is measured in a screened logger at 1.2 m.

There are many examples from frost trials where the canopy is much colder than a field weather station.

Along with the screened data logger we included an unscreened data logger at 1.2 m.

This unscreened logger at 1.2 m enables us to compare screened and unscreened minimum temperature (we would expect unscreened to be colder) and because it is installed above the canopy logger, we can check the difference in temperature between the canopy and 1.2 m (we would expect the canopy to be colder).

There is a closer relationship between the unscreened data logger at 1.2 m and the temperature in the canopy.

As expected, the canopy is colder than the unscreened logger at 1.2 m, but at these trial sites there seems to be a greater warming impact of covering the logger than the height of the logger.

So far in this article we have referred to the minimum temperature which is the coldest at some time during the night. Because the data loggers are measuring continually, it is also possible to calculate the accumulated hours below thresholds of 2 °C, 0 °C, -2 °C and the frost sum hours below 0 °C. Frost sum hours are calculated as follows: If the temperature for an hour is -1 °C, this is calculated as one frost sum hour and -2 °C is calculated as two frost sum hours. As shown in the table below, the effect of both logger screening and logger height shows up more in the number of hours below a threshold than the minimum temperature.

There is a reasonably tight relationship between the screened and unscreened minimum temperatures with a consistent pattern of the exposed data loggers being colder, especially at zero and below. By looking at zero degrees on the x axis (screened temp), the dots cross the Y axis about 2 degrees below the zero. This shows that the unscreened temperature is about 2 degrees colder.

Concluding remarks These results reinforce the importance of careful measurement of frost at head height of the crop.

The offset of 2 to 3 °C colder seemed to hold for the minimum temperature but the value of frost sum hours calculated from a screened logger at 1.2 m will be much less than an unscreened logger at head height.

Contributed by Peter Hayman, Dane Thomas & Bronya Cooper, SARDI Climate Applications.

Too busy to sit down and read?

Have a listen instead..

'Did we make Better Frost Decisions?' podcast out now Mallee Sustainable Farming

Skip the reading and hear the highlights from the team. MSF has dedicated a Farm Talk podcast to frost where we take a look back at the year that was and catch up with members of the GRDC Frost Extension Project team.

We chat to: Peter Hayman, SARDI Climate Applications about the data measured through Spring and the difference between BOM data and taking minimum temperature measurements in the paddock.

Frosted Scope barley

Naomi Scholz, AIR EP about the success of the variety and time of sowing trial at Tooligie on the EP. Jessica Koch, Precision Ag Consultant Breezy Hill Ag Services working on frost mapping with sensors for the Upper North Farming Systems frost demonstration site.

SA Southern Mallee farmer, Adam Morgan to review the data from Parrakie temperature sensors and how frost impacted his season.

Michelle McClure from Southern Farming Systems introducing the Frost Economic Scenario Calculator that will be available for all growers and advisors to model enterprise mix for frost mitigation planning.

Non frosted next to frosted barley heads

For more information contact Tanja Morgan tanja.morgan@msfp.org.au

Reducing the impact of frost with variety selection Ag Innovation & Research Eyre Peninsula The Ag Innovation & Research Eyre Peninsula GRDC Frost demonstration site is located at Tooligie, central Eyre Peninsula, and has been sown and managed by EPAG Research.

The demonstration was sown on 26 May and includes a range of wheat varieties with different maturities, a mixed variety treatment, an awnless wheat to give the option of a hay cut in the event of frost, and Spartacus barley as a comparison crop species.

The main aim of the demonstration was to answer the following question: Did sowing wheat varieties of different maturities sown on the same date reduce the impact of frost in 2021?

From the 14 August to 17 October from growth stage 31 (first node) to 75 (milk development, after flowering), there were 38 below zero events (measured with the temperature data logger located at crop height) and 18 below zero events (measured in the Stevenson screen).

There were no visible frost symptoms during early September, but by mid-October all wheat displayed severe frost symptoms. The barley was the only treatment not visually severely affected.

Harvest cuts were taken by hand on 19 October (possibly prior to full maturity for some varieties). The biomass ranged from 7.3 t/ha for the Spartacus barley, up to 11.4 t/ha for Mace wheat. The grain yields however ranged from 0.16 t/ha for the awnless wheat to 2.81 t/ha for the Spartacus barley. All of the wheat grain yields were less than 1 t/ha.

From these results, in these conditions, growing wheat, despite using varieties of different maturities, has been severely affected by frost and resulted in very poor yields. Growing barley was definitely a better option in this situation. The site is yet to be harvested with the plot header.

SPARTACUS

VIXEN

MACE

SCEPTER

ROCKSTAR

LRPB DUAL

DENISON

VIXEN

/ DENISON

MIXED

ADJACENT CROP (NOT FROSTED) CHIEF CL PLUS sown 26th May

Barley grain sample next to wheat frosted grain from biomass samples MACE

VIXEN

VIXEN

28th September 2021

For more information contact Naomi Scholz eo@airep.com.au

VIXEN

Creating frost zone maps for timely decision making Upper North Farming Systems

On the 21st October, Jess Koch downloaded the data from the frost sensors at the ten locations in the Frost Extension ‘Woolfords’ paddock.

It was decided between Jess and the grower (Todd Orrock) that the sensors would be left in the field until the crop was harvested in mid-later November, given that there has been history of late frost significantly affecting yield, it seemed appropriate to capture that data.

It was evident that there was considerable frost damage affecting the barley (at late flowering stage) at the low-lying site on the western end of the field.

The sensor sites on the ridges at the eastern side of the field were largely unaffected by frost.

Most of the damage, as reported by observations by the grower occurred from a frost event on the 12th of October. However, there were 11 occasions in total in late September/early October where the sensors recorded below 0 °C at this site.

The western sensor recorded sub zero temperatures between 8 pm and 6.30 am, with the lowest dipping to -5 °C. The sensor circled on the mid/eastern side, experienced far less damage from frost as the graph suggests below – with the temperature dropping below 0°C once in this period.

Fig 1 – A ‘landscape change’ map showing depressions, contours and ridges in ‘Woolfords’ paddock.

The frost sensor locations are shown by the green pins.

Photos of the crop in each location were taken on October 21st

Graph 1 – The Mid-Eastern Sensor in the blue zone (refer to landscape change map above) from 24/9/2021 to 21/10/2021. This zone has no visible signs of frost and the low temperatures have been far less extreme

Graph 2 – The Western sensor in the orange low lying zone (refer to landscape map above) from 24/9/2021 to 21/10/2021. This zone has obvious signs of frost damage and the temperature has dropped below on several evenings since the sensors were placed at the site in July

For more info contact Morgan McCallum morgan@unfs.com.au

Mitigating frost risk in a mixed farming system Birchip Cropping Group

BCG’s Frost Mitigation Trial has been a focus for BCG’s research team in season 2021, with recent frosts allowing for useful data to be collected. The trial is looking at the economics of late grazing, grain production and salvage hay production to paint a picture of the financial outcomes of different frost management decisions.

BCG researcher Genevieve Clarke is leading the research, jointly funded by The Yitpi Foundation, Hugh DT Williamson and the GRDC and is optimistic about the results from this year’s trial,

Genevieve Clarke

"We have experienced quite a few frost events this season, some occurring quite late that is likely to have affected later flowering crops and may impact grain quality.”

The team undertook flowering assessments to capture flowering dates and assessed how grazing might hold back development, pushing things into a lower-risk frost window: “What we are seeing so far is that recovery from late grazing has been quite good considering seasonal conditions. We are seeing a delay in flowering from grazing but are predicting the loss of the primary tiller due to grazing late may impact yield given the dry seasonal conditions,” Genevieve said.

Genevieve led a discussion regarding the trial at BCG Members’ Field Day this month with 150 farmers and advisors enjoying the opportunity to see first-hand the visual difference between treatments.

“Being able to show growers these trials is an important and enjoyable part of our research and extension efforts. By engaging with growers, it increases the reach and longevity of our research. BCG has collected heads from treatments and undertaken frost induced sterility assessments to determine the level of impact on grain development across the treatments, adding further value to the research.

While the research trial is being finalised for the first year, growers throughout the region have started harvest – with many starting in Lentils.

BCG Research & Extension Officer Genevieve Clarke with grazed and ungrazed samples

BCG’s Senior Manager Operations, Kelly Angel suggests that growers may find areas of frost damage, as she has seen there is some damage around in both cereals and pulses.

There may also be a need to take note of sample quality this year when harvesting – if pinched or distorted grain is in the sample, it may reduce the received grade.

"Frost effects are a function of severity and duration but there are no hard rules to what temperature below zero or what duration is needed to cause crop damage” explains Kelly “This is due to many other factors also influencing damage including soil type, elevation, stage of crop development, crop moisture status as so on.”

Late season frosts throughout the Wimmera and Mallee have meant that some growers have made the choice to cut some crops for hay, while others assessing the markets have decided to take the crops to harvest regardless. There will also likely be some crops that look better than they yield because of Jacks unwanted visit.

“We saw a couple of years ago that frost impacts late in the season meant that delivery of some commodities was challenging due to quality issues, in particular pulses” says Kelly “In that season, some growers took the extra step to store and clean grain on-farm prior to delivery to make sure they met the specifications, or in some cases improve the quality delivered.”

For more information contact Tom Draffen tom.draffen@bcg.org.au

Frost Economic Scenario Calculator - know your zones Southern Farming Systems

Southern Farming Systems is developing a Frost Economic Scenario Calculator with the collaboration of Michael Moodie, from Frontier Farming Systems.

This tool is designed to help you work through scenarios for your farm and calculate the impact frost has on your farm business bottom line.

The calculator allows you to enter your farming business system details and step through the frost impacts you have experienced or potential scenarios allowing you to compare up to 5 different management scenarios.

Frost damage is not a simple predictable outcome based on topography, weather predictions and simple modelling, it is very complex. This calculator is very qualitative and is only a guide of trends and relies on the information entered, experiences and interpretation by the user.

The calculator uses a zone approach to frost management, as frost damage impacts some farmers more than others and that each farm has paddock/s or farm zones that delineate their need to adopt frost strategies.

The calculator categorises the frost impact into 3 zone types, Frost Green Zone, Frost Amber Zone and Frost Red Zone.

Frost Green Zone is an area that has no frost risk and the business isn’t impacted at all by frost. There is no need to adopt any frost mitigation or avoidance strategies, and to do so would severely reduce its ability to push production or yield and grow high value crops.

Frost Amber Zone is in between the Green and Red Zones which sometimes gets frosted (always when the Red Zone is severely frosted) but mostly doesn’t and has production capability like the Green Zone.

Frost Red Zone is areas that are frequently or severely damaged by frost. If a grower adopts the same management decisions as in the Green Zone in the Red Zone, then it is likely that large losses will occur.

The calculator also uses a scale like rainfall deciles to measure the percentage frost impact on each enterprise categorised into Frostiest year, 1 in 10 Worst frost, 3 in 10 worst frost, Median frost 5 in 10, Below average frost and Least frosty year.

The output from the calculator will be the farm gross margin of each scenario for each frost year decile.

This will be displayed in a table and 2 graphs that will be downloadable as a pdf or print in hard copy.

Sample of the output page that is currently under development.

Michelle McClure, SFS said “We hope to have the calculator ready in early 2022 in preparation of 2022 season planning, when growers and agronomists can run through different enterprise scenarios and back up their gut feel of which enterprise is a better risk strategy for frost management for their farming system".

For more information contact Michelle McClure mmclure@sfs.org.au