Crop failure

Crops may fail for many reasons including:

• frosts
• flooding or drought
• economic factors and more.

How to identify frost damaged crops

Cereals are most susceptible to frosts between ear emergence and grain-fill while canola and legumes are susceptible whilst they are flowering. 

After a frost event farmers should aim to inspect their crops 7-10 days later for easy identification. 

• Look in the most susceptible parts of the landscape such as the lower parts of the landscape or paddocks nearby rivers and creeks. If the crop is damaged here proceed to higher ground and reassess, stopping every 10-20 paces across the paddock to assess frosting.
• Stem frost can occur in cereals if the head has not emerged from the boot.
• To check that the developing head has not been damaged, carefully dissect the plant from the top down to find the head of the plant inside the leaf sheaths.
• If the crop has flowered, open the florets to check if the grain is developing.
• It is a good idea to tag a few plants with tape and return a week later to determine if head/grain development and grain filling is continuing.

What to do following a flooded crop

There are essentially two options farmers can consider with affected paddocks:

• maintain a fallow prior to sowing next autumn
• sow a summer forage crop. 

The choice will depend to some extent on the number and class of livestock on hand for feeding over
summer.

Fallow

While a fallow would be appropriate on some paddocks because of a full moisture profile there would also be significant increases in weed spread with flood water having carried in weed seed and good moisture conditions providing ample opportunity for their germination.

It is likely that repeated spraying will be required to maintain a clean fallow even though this would prove expensive.

Forage crop

It is worthwhile considering summer forage crops on at least some paddocks as these can
provide opportunity for finishing or maintaining livestock over the summer period whilst offering
competition against weeds.

Within the summer forages, millet and forage sorghums are two main options. 

• Millet is a good option for both sheep and cattle while forage sorghums are better suited to cattle only.
• Generally, millet maintains better feed quality (digestibility, protein) than sorghums.
• There is a risk of prussic acid poisoning associated with sorghum so it is critical to observe grazing recommendations.
• Millet is a safer option than sorghum as it does not contain prussic acid.
• Both millet and sorghum can be grazed or used for silage or haymaking purposes.
• The stage of maturity of the plant has a significant impact on quality of the conserved forage.

Presence of residual herbicides can impact on the performance of both millet and sorghum so it
is important to check herbicide application records and check plant-back periods on herbicide
labels prior to sowing.

Grazing failed crops

If soil condition will withstand grazing, this can be a good use of a failed cereal crop. Note that not all failed crops are suited to grazing, for example chickpea is generally unpalatable. 

Failed canola crops can be high in both energy and protein and a useful feed source for livestock during extended dry times.

If stock may be sold, remember to check the withholding period for any pesticides that have been applied to the crop while still growing.

Livestock on a failed or stripped crop need to be monitored. Looking at the animals’ manure is the easiest way to ensure best use of the feed. 

If there is lots of whole grain in the manure, some animals in the mob may have sub clinical acidosis. Make sure you’ve got lime and salt in the paddock to increase salivation and bicarbonate production.

As the animals chew through the crop, the amount of grain available will decrease, and they will end up just eating stubble or stalks. In this case, the manure will “stack up” in piles like pyramids, indicating that there is lots of fibre in the diet and poor ruminal digestion occurring. If this is the case, supplying a lick to stimulate rumen activity would be a good idea. 

If grazing young, failed crops ensure vaccinations for pulpy kidney are up to date.

Stressed or failed crops turned into hay could potentially pose nitrate or prussic acid concerns. Levels should be checked before feeding. 

Other options for failed crops

Options for failed crops include:

• stripping failed crops
• making hay out of failed crops.

To calculate the best option financially, first estimate grain yield, dry matter yield and know the cost of production and commodity prices. 

Financial return

To calculate the financial return of each option, we need to know our cost of operations and the commodity price of each product. You may need to include other costs depending on your system, especially for the grazing option.

Unforeseen costs

Costs can include:

• nutrient removal
• implications on the following crop.

Nutrient removal - Once you know the removal per hectare it is possible to calculate the rate of fertiliser needed to replace removal. The cost of replacement is dependent on the fertiliser you use to replace the particular nutrient. In fertile soils, you may not get an economic response replacing nutrients that are in high abundance.

Removal of organic matter and ground cover - Organic matter including standing stubble improves the soils ability to hold moisture and nutrients as well as improving water capture and infiltration. Removing crop residues through harvesting hay or grazing can also reduce fallow efficiency and in summer conditions, decrease crop establishment as soils dry out more quickly. Maintaining or increasing groundcover will limit the chances of wind and water erosion.