If you are a grazier in our harsh western climate, it’s quite likely that you would have become accustomed to feed shortages available to stock during the later summer months.

Summer grazing crops such as forage sorghum and millet under irrigation produce high levels of feed during the hotter summer months, however usually start to finish off by this time of the year, and begin to produce forage which becomes lower in quality as temperatures begin to cool.

Lower grain prices and high stock market value has formed a niche for dual purpose winter grazing cereals including oats, wheat and in some cases barley, which aim to fill the feed gap.

In many cases, these cereals can be sown quite early, however there are a few limitations which must be noted.

Three conditions determine germination:

1. heat,
2. oxygen, and
3. water.

Unless these three conditions are all favourable, seeds cannot germinate properly.

Usually under irrigation, oxygen and water are available to the plant. Temperature however is a little different, as we are dictated by climate.

These cereals are ‘winter crops’ and like to be planted into cooler soils. Oats are usually the most tolerant of higher soil temperatures, so when sowing into warm soil conditions, oats would be the better choice over wheat or barley.

The consequences of planting a winter crop such as oats into ‘hot’ ground are similar to planting a summer crop into ‘cold’ ground, being reduced germination, reduced shoot length and effectively reduced plant establishment.

The optimum soil temperature range for the germination and establishment of oats is between 15°C and 25°C, and at a soil temperature of 35°C oats will not usually germinate.

Wheat and barley are usually happier a few degrees lower than oats. Soil temperatures can be easily monitored by using a soil thermometer at certain times of the day. Irrigation water can decrease soil temperatures, however after a few days this may not be the case.

Another issue to contend with when sowing ‘winter crops’ in warmer months is soil surface crusting.

Under warmer temperatures after irrigation the soil surface tends to dry rapidly, and results in baking and crusting of the top 2cm.

This causes a tight physical barrier that is almost impossible for seedlings to push through.

Often another irrigation just before seedling emergence is needed to soften the crust and allow the shoots to emerge, however this obviously means extra water use. This crust can be reduced by retaining organic matter, reducing cut areas when developing paddocks, and watering in cooler conditions.

Thirdly, it is important to select the right variety of cereal for each situation.

Varieties that are designed for early sowing produce high levels of quality forage, and will not go into head until they have filled their cold requirement.

Most grain varieties if sown in the warmer months will simply run to head and not produce the quantity and quality feed that you are after.

Early planting of cereals also increases the likelihood of diseases such as rust and virus development.

If you are aware of the risks and are prepared to manage them, sowing winter cereals, especially into late February, March and April under irrigation can be a very profitable exercise for graziers.

Contact: Barry Haskins, (02) 6960 1320.

– BARRY HASKINS

This story appears in Agriculture Today.