Planting summer crops into cooler soils

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With Spring fast approaching, some recent rain and a promising seasonal outlook, thoughts are fast turning to planting of grain sorghum, forage sorghum and corn. We thought it timely to again share important information related to planting summer crops into cooler soils.

Unless you have access to a weather station with a built-in soil thermometer, it will be necessary to manually take soil temperature readings to determine how close you are to optimum planting conditions.

TEMPERATURE CHECKS
A note on the practice of the early morning temperature check with a soil thermometer. Although this can provide an indication of the soil temperature at the coldest part of the day, it does not take into account the changes in temperature your crop will be growing through outside of this time.

A more reliable method is to take a soil temperature reading at around 7:30am and then again at 3:30pm each day. Readings at around these times will provide an indication of your maximum and minimum soil temperatures – from here you can calculate your daily average soil temperature.

You should take these daily readings over a period of a week or more to get an idea of the trend (rising, falling or flat). It is also important to look ahead at the weather forecast to determine if a cold spell may be shortly approaching.

SOIL TEMPERATURE TRENDS
A reminder of recommended minimum soil temperature trends prior to planting:
• Grain Sorghum: 16°C and rising
• Forage Sorghum: 14°C and rising
• Corn: 12°C and rising

EFFECTS OF SLOW SEEDLING EMERGENCE
If planting into soils cooler than the recommended minimums above, you should expect slower emergence and greater field establishment losses.

Planting when temperatures are lower than this can lead to a less than ideal plant population, reduced yield potential, management challenges later in the season or even the need to replant.

When the emergence of sorghum plants is slowed, they are more susceptible to attack from insects and other pests such as mice as well as disease infection.

It is important to remember to adjust your planting rate to consider any expected reduction in field establishment.

NOTE: The information provided in this publication is intended as a guide only. Advanta Seeds Pty Ltd (‘Advanta Seeds’) (including its officers, employees, contractors and agents) can not guarantee that every statement
is without flaw of any kind. While Advanta Seeds has taken all due care to ensure that the information provided is accurate at the time of publication, various factors, including planting times and environmental conditions may alter the characteristics and performance from plants. Advanta Seeds shall not be liable for any errors or omissions in the information or for any loss, injury, damage or other consequence whatsoever that you or any person might incur as a result of your use of or reliance upon the products (whether Advanta Seeds products or otherwise) and information which appear in this publication. To the maximum extent permitted by law, the liability of Advanta Seeds for any claim whatsoever arising out of the supply or use of or reliance upon the products and information in this publication (including liability for breach of any condition or warranty implied by the Trade Practices Act 1974 or any other law) is limited at its discretion, to the replacement of the products, the supply of equivalent products or the resupply of the
publication. For application to specific conditions, seek further advice from a local professional. © Advanta Seeds 2020.