Growing wheat in Victoria
Wheat is the most important cereal grain in world commerce. The framework for all winter crop production in Victoria is based on the principles and practice of successful wheat farming.
Distribution of production
The area sown to wheat in Victoria has been slowly decreasing over the last 5 years. At the last census, 2015, it was estimated that 1.6 million hectares were sown to wheat but the department estimates for the 2015 to 2019 seasons, the average has been 1.3 million hectares sown. Competition from legume crops and an increasing barley area is mostly the reason for the decrease.
In the last 5 years, the Mallee and Wimmera regions together accounted for about 60 per cent of total production.
Table 1. Estimated wheat production for Victoria 2015 to 2019
|Region||Production (tonnes)||Area Hectares|
Northern Country and North East
A key profitability issue for the industry is ensuring that research continues to deliver improvements in wheat quality in order to increase market share in a competitive world arena. From the farmer's viewpoint, continuous yield improvement is also important.
Wheat quality encompasses the suitability of particular varieties grown in certain environments for particular end uses.
Standards for harvest segregations for quality are maintained by Grain Trade Australia and are based on consumer demand.
All wheat varieties in Australia have a classification based on processing and end product quality which along with a range of physical standards contributes to a marketing standard or segregation.
Segregations which account for the majority of the Victorian harvest are:
- Australian Hard 1 (minimum protein 13.0 per cent)
- Hard 2 (minimum protein 11.5 per cent)
- Australian Premium White 1 (minimum protein 10.5 per cent)
- Australian Standard White (No minimum protein)
Special categories of segregations are:
- Australian Noodle
- Australian Soft 1
- Australian Feed
Varieties not meeting the specifications of these segregations will be received as Australian General Purpose.
Information on the varieties appropriate to each segregation is available from Grain Trade Australia.
Types of wheat
The high protein wheats sought by domestic millers for traditional bread products generally come from the Mallee. Deliveries which meet the receival specification are segregated as AH1. Elsewhere, generally longer growing seasons give higher yields but also greater variability in wheat quality. Most of this wheat is segregated either as APW or ASW.
Feed wheats by definition are not suitable for milling, but often have the potential for high yields when compared to milling varieties.
Feed wheats are most suitable for the 600 to 800mm rainfall or irrigation areas. In order to realise potential yields of 5 to 10 tonnes per hectare, these varieties must be sown early (mid-late April) in paddocks where moisture and nutrition are not limiting and the potential for waterlogging is mitigated. Other agronomic requirements are similar to those of the milling varieties.
Paddock selection and crop sequence
Historically wheat was grown in a rotation with pastures and a period of fallow, often bare cultivated. The advent of a range of pulse and oilseed crops, favourable economic outcomes from cropping and with a deeper understanding of management of disease and fertility issues, crops are normally sown every year in the same paddock.
Rotation is now rarely used to describe cropping systems as flexibility is the key to success. Changes in crop choice can be made at sowing time based on several factors.
Pulses, oilseed crops and barley offer disease breaks for many wheat diseases and differing genetic backgrounds of wheat varieties sometimes allow wheat to be sown in consecutive years. Incorporation of disease resistances into wheat has also virtually eliminated some diseases, such as cereal cyst nematode, and allowed more frequent sowing of wheat.
Wide row sowing with precision guidance techniques — (where crops are sown in the gaps between the crop rows from the previous season) — can also allow wheat to be sown more frequently.
Choice of paddock to sow wheat is therefore based on a range of issues. Economics, risk of production due to disease or weed pressures, herbicide options, seasonal forecasts, stored soil water and achieving a balance of risk with other crop types are some of the considerations which inform choice of crop.
Preparation of a seedbed to ensure good seed soil contact was an important element in successful crop establishment. Minimum and no till crop production systems have however proved that a fine tilth for a seedbed is not so critical.
Advances in equipment for minimum and no till systems has incorporated sowing implements with tynes and press wheels that create furrows. The furrow harvests water into the seed row and the press wheels ensure good seed soil contact. The use of disc seeding systems is increasing, which leaves the soil surface essentially undisturbed.
Shared knowledge within farmer groups has led to many of the changes in farming systems and these groups are a good source of advice relevant to a particular district.
Seasonal variability always modifies a calendar decision, but whether the season breaks early or late, farmers need to be prepared. Every year there is a weather limit on the window of opportunity for sowing. Sowing requisites and equipment need to be ready to exploit that window.
A season which breaks in April is ideal because of the opportunity to use all options. They also provide the best weed control. Long season (winter) wheat varieties are sown first in April then mid-season varieties follow in May and early maturing varieties in June. If the 'break' is later, long season varieties are dropped out for mid and early maturing varieties.
Many farmers have demonstrated the benefit of sowing a portion of the crop dry if a seasonal break has not been received by late April. These crops germinate rapidly when rain falls and generally make the best use of limited growing season rainfall.
Wheat yield and quality is an outcome determined by the genetic potential of the variety interacting with the environment, in combination with the farmers management.
The same variety may perform differently on a different soil type and rainfall regime.
Farmers now have a wide choice of wheat varieties and a range of marketing options. Individual research is required to determine the best choices. Sources of information are:
- the companies which market varieties
- National Variety Trials — an online database
- local advisers and agronomists
- Victorian crop sowing guide.
Virtually all wheat varieties are now covered by Plant Breeders Rights which means a royalty or fee is payable to the breeder or owner of that variety for each tonne of grain that a farmer produces. Collection point for the royalty or fee may differ between varieties and growers need to be aware of individual arrangements.
Depth of sowing
Deep sowing may delay or stifle emergence, while shallow sowing risks seed damage from herbicide uptake. The length of the first shoot (coleoptile) has a bearing on depth of sowing. If a variety is sown deeper than the natural growth extension of the coleoptile then the seedling may not emerge. Most current varieties are derived from so called semi-dwarf lines which have shorter stems and shorter coleoptiles than older varieties.
Seasonal differences in depth and availability of moisture influence decisions about depth of sowing. A sowing depth between 25mm and 50mm, depending on soil type and available moisture, is a useful guide to sensible seed placement. In moist conditions shallower may encourage faster emergence and crop establishment.
To achieve total ground cover and establish the foundation for maximum yield, a crop density of 150 to 200 plants per square metre is needed. This equates to a seeding rate of about 60kg per hectare in lower rainfall zones (up to 400mm annual rainfall) and about 80 to 90kg per hectare in the higher rainfall zones.
Sowing rate can be calculated by knowing the:
- seed weight
- germination percentage
- required plant density.
- Wheat seed with a seed weight of 4.5gm per 100seeds, germination percentage of 95% and a required plant density of 170 plants/m² = 4.5 × (10/95) × 170 = 80.5 kg/ha.
The source of seed is very important. Most farmers grow and store their own seed for use in the following year. However, when introducing a new variety or extra seed, it is sensible to source the best quality seed. If certified seed is not available, a thorough inspection for insects, weed seeds or mixed grains prior to purchase is the obvious precaution.
Seed dressings for the control of smuts and bunts should be applied to all wheat seed prior to sowing. Although major losses from these diseases are now rare, this is due to the routine use of seed treatments. Seed not treated prior to sowing may result in yield losses as high as 85%. See bunts and smuts of cereals for information on seed borne diseases managed by seed dressings.
Some seed dressings can also suppress a selection of wind or stubble borne diseases, however some chemicals can reduce coleoptile length. For more information on this refer to the factsheet on Cereal Seed Treatments, from the PIRSA Factsheet Library. Advice on products and application rates is also available from cropping advisors or chemical resellers.
Soil tests are available to assist in the assessment of paddock nutrient status.
Adequate phosphorus is essential for the early growth of wheat. Most Victorian soils are low in available phosphorus, and much of the crop requirement will need to be supplied through the application of fertilisers at sowing time. Paddock history of phosphorus application and crop yields, in conjunction with soil test results and economics of application will determine the rates required.
The rule of thumb is a requirement for 3kg per hectare of available phosphorus for each tonne of wheat anticipated. The application is then adjusted in the light of soil test results.
Table 2 — Adequate soil phosphorous ranges (Colwell) for different soil types.
|Soil test reading (Colwell)||Soil type|
20 to 30 mg/kg
25 to 35 mg/kg
30 to 40 mg/kg
Nitrogen availability is equally important. Besides its role in plant growth, the availability of soil nitrogen at grain fill, along with soil moisture, is the key determinant of grain protein.
The farmer has a high degree of control over nitrogen build up and availability through the choice of:
- crop and pasture choices
- weed control
- use of long fallow
- stubble retention and tillage methods.
The availability of nitrogen in the soil will be affected by many factors such as soil organic matter and paddock history including:
- soil type
- moisture content
- time of year
- stubble retention.
High yields are a drain on soil nitrogen. Conversely, low yield and summer rain to mineralise nitrogen can mobilise soil nitrogen for the next crop. Soil tests for N assessment should be done as close as possible to sowing time and at the same time each year. Wheat requires approximately 40kg N per tonne of anticipated yield. This N can come from both soil and fertiliser sources. The soil test result, in conjunction with anticipated yield, estimated mineralisation and fertiliser applied can be used to budget for N demand and supply by the crop.
Cropping advisors are a good source of support in determining fertiliser application strategies.
Crops should be monitored to gauge early crop growth factors such as:
- seedling density
- weed population
- presence of insects and disease
- general crop health.
All these factors impinge on the potential grain yield. Records of rainfall received and soil water to maximum rooting depth at sowing and harvest will allow the farmer to assess the water use efficiency (WUE) of the crop.
WUE = kg grain per mm effective growing season rainfall per hectare.
Wheat has a potential WUE of approximately 20kg/mm/ha. A crop reaching 80% or more of its potential WUE reflects good management.
To achieve maximum potential yields, early planning for weed control is essential. Weed assessment of the paddock should start the year prior to cropping. This will guide the farmer to choose the appropriate weed control strategy required:
- winter cleaning of pastures
- control of grass weeds in broadleaf crops
- chemical fallowing.
Weeds encourage the transfer of disease and pests and use nutrients and moisture that could be converted into grain by the crop.
Once a weed problem is encountered there is a wide range of herbicide options available to control them. Not only is the immediate removal of weeds important but there is a need to avoid developing resistance to a particular herbicide or group of herbicides.
Rotation of herbicide groups is an important consideration as well as any potential residual issues for subsequent crop choices.
Consulting cropping advisors and resellers is recommended for both the choice of a tactical option to control weeds and to develop longer term weed management strategies.
An estimated 50 per cent or more of the wheat produced in Victoria is consumed locally, within the state. This is as milling wheat, stockfeed and other uses such as starch production. The rest is exported where prices are very dependent on the world market.
In years of high yields a greater portion of the crop will be available for export.
Plant breeders are producing varieties which offer a range of traits, one of which is grain quality. Wheat growers are responsive to market demands and choose varieties which offer the best financial returns. It is important for growers to determine which varieties are best suited for their district and one factor in that choice is which market will that product be suitable for and will that market accept the grain produced.