Management options for a frosted crop

Page last updated: Thursday, 31 January 2019 - 4:12pm

Frost is difficult to manage. It has a significant economic and emotional impact on the whole community. A good understanding of the extent of damage after a frost event will help inform salvage options and minimise the impact on the following season. The department has several climate tools which provides up to date information about the current season and its potential impacts on cropping and agriculture. This page outlines those climate tools and explores the possible salvage options and harvest considerations of a frosted crop.

Climate resources

Seasonal climate information provides frost risk maps which shows the average number of low temperature events occurring in the months when crops are at most risk of frost damage from 1975-2014.

The Extreme weather events tool uses data from DPIRD's extensive weather station network to map extreme temperatures, either below or above a specified threshold. It provides real-time information about the location, duration and severity of frost and heat stress events, to help grain growers manage accordingly to reduce their financial impact.

Salvage options

There are a number of options available for managing crops that have been frosted. The following table highlights these options and the pros and cons of each. The suitability of each option will be dependent on the severity of the frost, what can be done at the cheapest cost and give best return on investment and maximising weed control.

Table 1 Salvage options to manage frosted crops
Option Advantages Disadvantages Considerations
Harvest
  • No damage estimates required
  • Salvage remaining grain
  • Handle stubbles and prepares for next year
  • Costs may be greater than returns
  • Need to implement weed control
  • Threshing problems
  • Need to remove organic matter

Grain quality may also be compromised depending on the frost timing. Frost affected grains usually have a lower hectolitre weight and higher screenings. Adjusting header settings and/or grading can be beneficial but check the feasibility first.

If keeping seed for next season, it is important to source seed from least-affected areas to maximise establishment. Seed quality can be tested closer to seeding by DPIRD Diagnostic Laboratory Services for a small charge.

Hay/silage
  • Stubble removed
  • Weed control
  • Cost per hectare
  • Quality may be poor (especially wheat)
Consider the demand and opportunity for marketing hay, potential for on-farm storage and use of hay from the frosted crop and the likely costs and returns from haymaking. Depending on soil moisture the plant may re-tiller and grain can be harvested.
Chain/rake
  • Retains some stubble and reduces erosion risk
  • Allows better stubble handling
  • Cost per hectare
  • Time taken
Consider weed burden, wind and water erosion.
Graze
  • Feed value
  • Weed control
  • Inadequate stock to utilise feed - stock feed unevenly
  • Remaining grain may cause acidosis
  • Stubble may be difficult to sow into

The feed value will vary depending on crop type. Frosted pulse crops will have minimal grain present, so can't be considered ideal for finishing livestock.

Spray
  • Stops weed seed set
  • Preserves feed quality for grazing
  • Gives time for decisions
  • Retains feed
  • Retains organic matter
  • Difficulty getting chemicals onto all of the weeds with a thick crop
  • May not be as effective as burning
  • Boom height limitation
  • Cost per hectare
  • Some grain still in crop
Hay freezing the damage crop before grazing will maximise the fodder quality and rotation benefit.
Plough
  • Recycles nutrients and retains organic matter
  • Stops weed seed set
  • Green manure effect
  • Requires offset discs to cut straw
  • Soil moisture needed for breakdown and incorporation of stubble
It will depend on the rotation option planned for next year. A pasture option has different requirements to a crop option where stubble must be prepared.
Swath
  • Stops weed seed set
  • Windrow can be baled
  • Regrowth can be grazed
  • Weed regrowth can be sprayed
  • Can preserve some of the nutritive value of the crop without the expense of applying desiccant herbicides
  • Relocation of nutrients to windrow
  • Low market value for straw
  • Poor weed control under swath
  • Cost per hectare
More suited to lighter textured soils where erosion may pose a problem for green manuring.
Burn
  • Recycles some nutrients
  • Controls surface weed seeds
  • Potential soil and nutrient losses
  • Fire hazard
Consider wind and water erosion risk. Particularly if grazing will occur before burning.

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