Canola, other brassica species, ryegrasses, rye, oats, wheat, triticale and barley are crops grown extensively for winter feed.
Commonly cereals and canola are grown as dual purpose crops, aiming to provide about 30-90 days winter grazing for around 25 dry sheep equivalents/ha followed by lockup for grain recovery. Canola has been especially impressive these last three seasons where follow-up rain (post establishment) has been lacking or long delayed.
Elders agronomist Peter Watt of Cowra, for example, reports that canola tap-root systems have allowed faster deep rooting (2.0cm day) and capture of subsoil moisture (supported by CSIRO studies).
In contrast, grass (example cereal) species requiring follow-up rain to allow for secondary root development (for anchoring and deeper water extraction) has resulted in often greatly delayed and reduced winter feed.
Stock have often been on canola weeks earlier than cereals in seasons like 2017, 2018 and 2019 Peter Watt stresses.
With good management and reasonable seasons, dual purpose crops can yield similar grain returns to grain-only ones, but with valuable often badly needed winter grazing.
When late winter/early springs are dry, options to use dry-matter for grazing, silage or hay are alternatives to grain for economic assessment. In drought years like 2017 and 2018, returns from fodder options were often highly profitable.
The secrets to good grazing or dual-purpose crops are similar to grain only crops. Conserved moisture over the fallow period, high standard weed control, part of good rotations, high soil fertility, timely sowing, disease and pest management, appropriate sowing technology and choice of variety are all important considerations for best reliability.
Like many farmers, we are pushing out our sowing window to improve probability of establishing dual purpose or grazing only crops in time for good winter feed.
According to the app CliMate, if we can sow on a 10mm or more rain event between mid-February and the end of April, based on 120 years of rainfall records from our nearest recording station (Purlewaugh), we have a 96 per cent probability of being able to sow timely. If we required 20mm, the probability drops to 86pc and if we needed 20mm over a later start date (example March 10) the probability drops to 76pc.
Research is not clear as to how early one can sow dual purpose or grazing only winter crops, with guidelines generally conservative.
Several farmers are pushing early sowing beyond normally advocated times. This is both for cereals and canola, with success commonly good. I like most agronomists, am reluctant to promote a practise like very early sowing not "science based or collaborated" by research. Hence the caution.
I feel very early sowing is possible with decisions weighted by temperature forecasts (obviously don't do it with a heatwave pending) as well as paddock soil type and moisture status.
Being able to sow timely is greatly aided by having good sub soil moisture, which for most areas means effectively conserving any summer rain over the fallow period.
Some consider summer herbage growing on fallows as valuable grazing, but mostly this will be at the expense of quality winter feed. Plus, good fallow weed control is an important part of depleting weed soil seed banks and preparing land for future pastures or crops.
Canola has been especially impressive these last three seasons where follow-up rain has been lacking or long delayed.
- Bob Freebairn
Stubble retention from a previous crop or pasture is helpful for early sowing and helps keep moisture closer to the surface, creates better rainfall capture and lowers soil temperature by up to six degrees.
Medium to lighter textured soils can also better suit sowing on a smaller rainfall event (improved probability of sowing on time). Sowing quickly is also often critical.
Where good grain recovery after early sowing is aimed for, post grazing varieties with "winter habit" or "vernalisation requirement" offer higher tiller survival. Canola breeders are making big gains in variety development, with several updates coming through the assessment process.
Where grazing is the main aim (compared to dual purpose), late maturing "winter habit" types allow for long vegetative (high quality) phases and is available in canola as well as cereal varieties.
In milder environments these types (canola and cereals) are also used in spring/summer sowings, with grazing possible over summer and into the following autumn winter.
Next week: Selecting next year's crop varieties now.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
