How to know when to sow

By Tim Bartimote - Cropping Officer

With widespread rain across our region we are seeing increased enquiry from farmers keen to make the most of this early autumn break. So, how early can you start to sow?

Here are some key points to consider this season.

Understanding your Sowing Windows

Sowing a variety outside of its recommended planting window significantly increases the risk of  yield loss due to frost damage, if sown too early or heat stress, if sown too late. It is important to understand that the recommended sowing windows are calculated to ensure the variety will flower and fill grain during the period where frost and heat stress risk is at its lowest. This ideal flowering period changes from region to region, hence why some areas can sow one variety earlier than others. For more information on recommended sowing dates check out the NSW DPI Winter Crop Variety Sowing Guide in Further Resources.

Measure your Soil Temperature

Another consideration is soil temperature, a point made by Callen Thompson - Central West LLS Mixed Farming Officer, in a previous article (see further resources). For example, in cereals, sowing too early can expose seeds to high temperatures and significantly reduce establishment. It is recommended that oats be sown in soil temperatures between 25°C to 15°C while 25°C to 12°C is suggested for barley and wheat. Measure soil temperature at 9am, at sowing depth, over 3 days to see if it is adequate.

Select the Right Variety

Apart from climate the other big driver in recommended sowing dates is the physiology of a variety. These are the drivers that cause a variety to move from vegetative to reproductive maturity. They include vernalisation, photoperiod and day degrees. Producers can manage their risk, if wanting to sow early, by understanding the growing habits of different varieties. Selecting a winter type, long season Spring type or European variety can enable a last week of March, first week of April sowing event. However, keep in mind other characteristics that are important to your cropping system, for example grain quality. As some varieties can be sown early but are more aimed at the dual purpose market and will only reach FEED or ASW classifications. Make time to discuss this with your local agronomist and identify varieties which best fit your situation.

Consider Grazing Management

The other non-physiological driver which can be included is grazing management in dual purpose varieties. To an extent, maturity can be influenced with grazing management. However, this is not nearly as reliable as physiological drivers. As maturity can only be delayed by 1, maybe 2 weeks at the very most. This is also assuming crops are evenly grazed across a whole paddock. Varieties are not strictly controlled by one driver but a varying combination, where a certain driver may have more control over maturity than the others.

Focus on your Business Goal/s

Understanding your local climate, your chosen variety and what drives it to maturity will allow you to make an informed decision on optimum sowing times. It all comes back to determining what your goals are. If the aim is to re-establish ground cover or provide winter feed for stock, despite potential yield reductions then that is a good outcome. Bear in mind, sowing quick varieties very early for feed will mean that the crop will run to head quickly and not achieve suitable biomass for grazing. It is still important to use varieties which are relatively suitable for that time of year to achieve the desired results. However, if it is maximising grain yield then sowing within the recommended window is ideal. Ensuring that when it does flower, it’s not exposed to extreme periods of yield-limiting stress.

For more information feel free to contact your local LLS Ag Advisor.

Further Resources:

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