- Owners: Wayne and Terese Thomas
- Location: Youanmite, Victoria
- Farm area: 1540 hectares, 1500ha cropping
- Average annual rainfall: 450 millimetres
- Soil types: sandy loam over clay
- Soil pH: 5 to 6
- Crops grown: wheat, canola, oats, vetch, faba beans
Northern Victorian grower Wayne Thomas was busy loading wheaten and vetch hay onto trucks dusted with brittle soil in the dry heat when GroundCover™ visited his 1540-hectare property at Youanmite, about 25 kilometres south-west of Yarrawonga.
Triggering this on-farm activity was the forecast for a soaking the following day, heralding a brief reprieve from the prolonged dry conditions experienced during the 2018 growing season on the familys farm.
Waynes risk-management response to protect high-value hay from potential weather damage highlights the influence of increasingly sophisticated seasonal forecasting in helping to shield cropping operations from variable seasonal conditions and a changing climate.
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Seasonal forecasting is one of many tools the second-generation grower uses to frame a big-picture vision of the climatic and seasonal influences, which guide his approach to risk management across cereal, oilseed and legume crops grown for grain and hay.
Each tool only assists with part of the overall picture, so we use a suite of tools to build the most accurate picture of our farm business risk profile, he explains.
For Wayne, these tools pull together the past, present and future of the farms cropping program, which consists of wheat, canola, oats, vetch and faba beans. The tools include:
- First-hand seasonal experience and paddock records (the past)
- Up-to-date soil moisture and weather data collected on-farm (the present)
- Seasonal and climatic forecasts (the future)
- A web-based decision-support tool.
For example, Wayne analyses data collected by a deep soil-moisture probe and weather station installed on his property by Agriculture Victoria to help determine the yield potential of crops based on plant-available subsoil moisture and on-farm weather conditions.
From a fixed paddock location, the weather station records climatic information, such as in-crop temperature and received rainfall, while sensors in the capacitance probe record subsoil moisture at 10-centimetre increments from a depth of 30cm to one metre in the soil profile.
Each tool only assists with part of the overall picture, so we use a suite of tools to build the most accurate picture of our farm business risk profile
In the dry 2018 growing season, Wayne used data sourced from both the weather station and moisture probe to help inform a key decision to cut some wheat, canola, oats and vetch for hay instead of harvesting them for grain.
He says the weather station showed paddock temperatures, which plummeted from minus 1.3 to minus 6.2°C between 1am and 7am on 29 August, caused severe stem frost that saw cereal and oilseed crops 'frozen in time'.
Wed never experienced frost like that before. In the past weve only had partial stem frost, " he says.
Some of our wheat and oats didnt grow another centimetre.
Wayne says the arrested crop development was reflected in the probe data that showed his frost-damaged wheat had stopped drawing moisture from the subsoil, suggesting it had stopped growing.
This frost impact on the Thomas familys farm was also observed by Agriculture Victoria seasonal risk agronomist Dale Boyd, who manages a Victoria-wide network of probes and weather stations on growers properties.
Waynes inspection and monitoring showed the severe frost damage was not limited to 350ha of wheat. It caused major damage to most of the farms 600ha of canola and 250ha of oats as well.
But he says lessons learnt from frost damage in past cropping seasons, plus in-crop examination, confirmed losses were less severe where crops were sown into legume stubbles.
This Wayne attributes to the increased plant-available soil moisture following legume crops compared with cereals, and the dry conditions known to exacerbate frost-damage.
Apart from frost losses, other considerations that influenced Waynes decision to cut about two-thirds of his crops for hay last year were short and long-term seasonal and climate forecasts.
He relies on the seasonal forecast commentary The Break, produced by Agriculture Victoria seasonal risk agronomist Dale Grey.
The Break provides seasonal forecast summaries and compares forecast models, including Bureau of Meteorology (BoM) models, and soil moisture data for three to six month periods.
For instance, the short and long-term outlook in early September for continuing dry conditions led Wayne to cut some wheat and vetch for hay, even though it escaped frost damage, to help 'salvage profitability' from these moisture-stressed crops.
Based on past experience, paddock data and seasonal forecasting, we know how much moisture crops need to fill grain, he says.
So if theres no moisture left in the soil profile and the seasonal outlook is hot and dry in September, its often safer to cut at-risk crops for hay."
Chasing the 'most profitable, low risk' management option, Wayne adds that forecast information is carefully measured against the backdrop of long-term crop yield averages, and crop dry matter cuts that last year ranged from 1.7 to 2.5 tonnes/ha.
Based on past experience, paddock data and seasonal forecasting, we know how much moisture crops need to fill grain
Wayne also fine-tunes his crop choices and inputs to match predicted seasonal conditions.
For instance, where seasonal climate models forecast low decile conditions, and the probe on his property shows depleted subsoil moisture, he might replace part of his wheat or canola area with less-thirsty vetch or oaten hay.
We dont dramatically change our area planted to different crops in a dry season, but we may pull 100ha of wheat or canola from our program, he says.
And he might also adjust his nitrogen rates based on seasonal and climatic predictions as well.
In a high-rainfall season, Wayne usually applies 30 to 50 kilograms of nitrogen/ha to help maximise grain productivity and profitability where cereals, with high yield potential, are sown into legume stubbles.
But in the low-rainfall 2018 growing season, no nitrogen fertiliser was applied to the farms stubble-sown cereals a move that saw him secure better gross margins from parched crops, showing low yield potential.
Waynes seasonal risk-management toolbox also comprises the web-based decision-support tool Yield Prophet®, used to estimate crop yield potential based on predicted rainfall and soil core testing, plus BoM Indian Ocean Dipole outlooks known to influence on-farm rainfall.
GRDC Project Code: DAV9176117
More information: Wayne Thomas, 0409 285 204; Dale Grey, 0409 213 335, firstname.lastname@example.org; Dale Boyd, 0417 339 804, email@example.com