Assessing frost damage & making decisions on hay vs grain

Key messages

• Make decisions early – compare the economics to help decision making easier
• Assess damage on a paddock-by-paddock basis and create a list of best to worst
• If the decision is made to cut hay, focus on making a quality product
• Keep records of the factors that affected your decision and how you came to that decision, as it may be useful to you in the future if the situation arises again

Frost damage can significantly impact crop yields, particularly during critical growth stages. For growers dealing with frost-affected paddocks, timely assessment and decision making are crucial. One option to mitigate losses is cutting the crop for hay, but this requires careful evaluation of potential yields and market opportunities.

This article offers practical steps for assessing frost damage, estimating hay yield, and comparing the profitability of harvesting grain versus hay. By making informed decisions early, growers can maximise their returns while maintaining the quality of the final product.

Riverine Plains is here to support members throughout this process and are offering assistance with drying crop samples to determine DM for potential hay yield.

Assessing frost damage

Frost damage presents itself in different ways depending on the type and growth stage of the crop. Always walk into the crop to assess damage, as plants on the edges may be less affected. Also check low-lying areas and light textured soils, tagging plants and monitoring their progression over a period of 7-10 days.

Canola

While frost at flowering is not ideal, the plant still has time to recover and new buds should develop normally. Key signs of damage in canola during flowering include bud discolouration, flower abortion and pod abortion. 

Frost can cause significant economic (yield) damage during pod-fill. Key signs of damage during the pod-fill stage includes aborted, stunted or twisted pods and discolouration. Watch this video produced by GRDC for more information on how to identify frost damage in canola. 

Wheat

Signs of damage in wheat will also depend on the plant’s growth stage. During booting and early ear emergence, look out for undeveloped spikelets and bleaching at the base of the head. Frost damage during flowering in wheat shows up as pale, banana shaped anthers, underdeveloped heads and missing or bleached florets.  Watch this video for more information on frost damage identification in wheat. 

Damage can vary significantly across a paddock, so its important to inspect the crop thoroughly to determine the level of frost damage a before making a decision. Light damage might still allow for recovery, or minimal yield loss, while severe damage will require alternative action. Low-lying areas, lighter soils and areas with heavy stubble retention are likely to suffer more. Consult your agronomist to estimate how any suspected frost damage might impact the potential yield.

Estimating hay yield  

If the grain crop is unlikely to yield well, the crop can be salvaged for hay (or silage) when there is enough dry matter (DM). To estimate hay yield, the following method can be applied: 

Step 1: Cut one metre of crop row from five representative sites across the paddock, cutting at the same height the crop will be mowed at. The area cut in square metres is equal to the number of rows sampled (five) x the row spacing in metres. 

Member only service: Riverine Plains is offering to assist members determine their potential hay yield - just bring a sample to the office and we can dry it down in our industrial ovens to help determine the crop dry matter and hay potential. If you are bringing a sample to the office you can stop here and we will do the rest. 

Step 2: Record the fresh weight in kilograms. 

Step 3: To calculate dry matter percentage, cut the sample into pieces roughly a centimetre long, to aid drying. Weigh a subsample of 100 to 500 grams and dry. 

Refer to this document for further information on the mircowave drying method - Measuring dry matter content of forages

The dry matter percentage is equal to the dry weight ÷ subsample fresh weight x 100. 

Step 4: Now, calculate the hay yield. Keep in mind that approximately 20% of the hay may be lost during baling. Hay typically contains 12–15% moisture, so assuming 15% moisture and 20% baling loss, the formula for calculating hay yield in tonnes per hectare is:

Hay yield (t/ha) = dry matter percentage (Step 3) x fresh weight (Step 2) x 1.15 x 0.8 x 0.1 ÷ area cut (Step 1).

Comparing the profitability of hay vs grain

Sometimes it can be difficult to work out the best way to proceed using yield predictions alone. Use this hay vs grain calculator to help you compare the $/ha return of each option. When making the decision, consider that hay market demand and prices can vary, and it is a good idea to have a buyer lined up before making the decision to cut.

Canola hay

Canola can produce high-quality hay when cut at the optimal time. The most valuable parts of canola hay are the flowers and leaves. Late flowering typically marks the point of peak dry matter yield, while cutting during the flowering stage ensures the best feed quality, leading to improved market prospects and animal performance. 

Key considerations:

Nitrate levels: Generally, hay or silage with less than 5000 parts per million (ppm) nitrate on a dry matter basis is safe, however hay or silage with 5000 to 10,000ppm is potentially toxic when provided as the only feed. Most issues occur when hungry stock are given unlimited access to the hay or silage. When introducing any new feed to stock, do so gradually. It is also important to do a feed test to determine the exact nutritional value and assess nitrate levels. 

Stem moisture: Canola stems are very fibrous and the stem does not give up the moisture held within very easily. Cutting the crop slightly higher up the stem will reduce risk of spoilage and fire in storage, however the dry matter yield will also be lower. Conditioning will help release the moisture from the stem, help the crop dry faster and generally makes the stems more palatable to livestock.

Nutrient loss: Also consider the impact of nutrient export associated with hay production. The potassium and sulfur removed will need to be replaced to maintain yield potential of following crops.

Ensure all chemical withholding periods are met prior to cutting crop for hay.

Cereal hay

Similar rules apply when choosing to cut cereal crops for hay. Timing is key to making a quality product and feed testing is essential to know the nutritional value for your livestock and for marketing.

Cutting too early or too late can affect the quality and nutritional value of the hay. Monitor crops closely, the ideal time to cut is between flowering when you can see the white anthers appear, up to the watery ripe stage when you can squeeze the grain and watery green liquid appears. 

The key to making hay is not to rush the process. Only bale when the windrows are at the correct moisture, baling with too much moisture will significantly increase chance of bale spoilage and shed fires. Aim for all your hay bales to have a moisture range of between 10-16%. Optimum moisture content for baling hay depends on bale size and density.  The upper limit for large round bales should be about 14–16 per cent and large square bales 12–14 per cent. 

Having the ability to store bales in a shed to maintain quality will help spread income across the year and prevent losses. Bales that are stored outside should be placed on well-drained ground with all-weather access for trucks. 

Don't forget you're not alone

If you're feeling overwhelmed or uncertain about how to manage frost-damaged crops or make decisions regarding hay production, it's important to know that help is available. Reach out to your agronomist or local farming support networks for guidance. Riverine Plains is also here to assist with drying samples to estimate hay yield.

Don’t hesitate to ask for support, working together can make a big difference in navigating these challenges. More information on where to seek help is in the resources section below.

Resources

Frost identification guide canola and pulses | GRDC

Tips for identifying frost damage | GRDC 

Dry matter calculator | Agriculture Victoria 

Hay vs grain calculator | Agriculture Victoria 

Broadacre crops salvage calculator | NSW DPI

Hay market report 20 September | AFIA

Hay and silage factsheet | GRDC

Feed quality testing | NSW DPI 

Tips for a profitable hay season | Feed Central 

Tips on how to have those difficult conversations & check in on people you think might be struggling | R U OK 

Designed by Australian farmers to help other Australian farmers cope effectively with life’s challenges | ifarmwell 

Support | National Centre for Farmer Health 

Services provided | Rural Aid 

Information for primary producers | Rural financial counselling service SNSW 

Information for primary producers | Rural financial counselling service NE Victoria 

For more information, please contact the Riverine Plains office on 03 5744 1713 or email Member Engagement Manager Lynn Macaulay at lynn@riverineplains.org.au