Profitable pulses – it’s all about the harvest window
GroundCover™ Issue: 118 | Author: Tim Weaver
- Correct desiccation timing provides uniformity in seed moisture
- Harvesting at the optimum moisture content means fewer grain defects
- Premium prices come from harvesting at the optimum moisture
- Correct storage of pulses ensures optimum germination if retaining for seed
- Setting up header front and drum speeds correctly improves pulse quality
With this year’s pulse production up on previous years, buyers may be more discerning about quality; research continues to show the benefits of harvesting at the optimum time
When it comes to delivering high-quality pulses likely to attract price premiums from buyers, there are several factors to consider.
Grain quality and prices can also suffer if there is mechanical damage, weathering and seed staining. Moisture levels at harvest also affect the quality of grain in storage.
If harvesting for seed, germination is improved if grain is harvested at 12 to 14 per cent moisture and stored in aerated silos, or graded and bagged as soon as possible. Crop-topping with herbicides before crop maturity may reduce grain quality and seed germination.
Harvest delays cost growers and the pulse industry a lot of money. It is not unusual to see a four-to-six-week spread in the harvesting of pulse crops that were established on the same sowing rain. Many late-harvested crops are often about eight per cent moisture, whereas the maximum moisture content for receival is 14 per cent with market preference at 12 per cent.There are several reasons why delaying the harvesting of pulses might be tempting:
- a clash with wheat or barley harvesting;
- the perception of a greater chance of achieving premiums for Prime Hard or Australian Hard wheat or malting for barley, even though in reality the premiums for harvesting pulses at the optimum time are often greater;
- the false perception that pulses tolerate
- the weather well;
- uneven ripening if not desiccated or windrowed, especially when grown on heavy clay or variable soils; and
- the false belief that pulses are slower or more difficult to harvest (this is not the case if they are desiccated and the header is correctly configured).
Pulses can be profitable if a professional approach is taken to production and marketing, rather than treating them as ‘secondary crops’ planted last, harvested last and sold to the nearest buyer.
Delays lower yield
Yield losses increase the longer harvest is delayed. For example, while faba beans are not normally prone to pod splitting and shelling out in all but extreme wet weather conditions, they are prone to pod splitting and pod drop after weather events if the plant has dried.
From a financial perspective, grain losses from a two-to-four-week harvest delay have ranged from $93 to $238 per hectare, depending on seasonal conditions.
Most losses were caused by pod loss at the header front or from unthreshed pods lost out the back of the machine.
In faba beans, for example, lodging can increase the longer they are left standing, and the risk is higher if the crop is high yielding and planted on wide rows.
It is also worth considering what a loss of moisture below the Australian pulse receival standard of 14 per cent moisture content maximum leads to, for example:
- 500 tonnes of faba beans at 14 per cent grain moisture and $450/t is worth $225,000; and
- the same grain harvested at 8 per cent moisture delivers 470t and at $450/t is worth $210,600 – a loss of $14,400.
Grain quality deteriorates the longer mature pulses are exposed to weather.
For example, seed coats of faba beans are prone to cracking if exposed to wetting and drying from rain or heavy dew.
Expansion of the seed as it absorbs moisture and then contraction as it dries weakens the seed coat, rendering seed more susceptible to mechanical damage during harvest.
Levels of cracked and damaged grain can be as high as 50 per cent in extreme cases of weathering and prolonged rainfall.
Faba beans and broad beans that do not meet the number one receival standard of six per cent maximum defective beans need to be graded. This results in:
- $15 to $25/t in grading costs; and
- downgrading of the seconds into the stockfeed market at a value of $120 to $140/t.
Early harvested pulses are more resilient to breakage during harvesting and subsequent handling, even at low moisture contents.
Some faba beans and broad beans are processed into dahl or flour by removing the seed coat (hull) and splitting the cotyledons. However, the visual appearance is still critical for marketing.
Older seed, darkened with age, splits better than new-season grain. The milling process uses abrasive-type mills to gradually abrade the seed coat from the cotyledons and is reliant on the seed coat being firmly attached to the cotyledons.
Cracking and weakening of the seed coat before processing substantially reduces the recovery percentage of splits and the quality of the final product.
Faba beans and broad beans that have been weathered after rain are difficult to thresh at harvest and often contain higher levels of unthreshed pods and pod material.
Darkening of the seed coat is caused by oxidation of polyphenol compounds (tannins). Conditions that accelerate seed-coat darkening include rainfall, cool-to-mild temperatures, high humidity and sunlight.
While there is usually no direct penalty or discount for a moderate degree of seed-coat darkening, it does have a significant impact on the marketability of the product and the reputation of the Australian industry as a supplier of high-quality product.
Quality is becoming increasingly more important as Australian traders attempt to establish market share against other bean-exporting countries (France and the UK).
It is likely we will see more segregation and premiums paid for lighter-coloured, large-seeded faba beans and broad bean types as new varieties with these traits are developed and the Australian industry becomes more quality conscious.
Weathering and mould
Weathering of seed caused by delayed harvesting can increase mould infection. High levels will also cause darkening of the seed coat. Humid (above 70 per cent relative humidity), wet conditions favour the development of a range of fungi in late-harvested bean crops.
While Alternaria species usually predominate, Aspergillus, Cladosporium and Penicillium species may also be present.
Increased risk of late ascochyta infection can develop on dry, senescing pods under wet conditions, and can penetrate through to the seed in susceptible varieties.
The current export receival standard for visible ascochyta lesions is a maximum of one per cent on the seed cotyledon (kernel). Current Australian Pulse Standards are available on the Pulse Australia website.
Native budworm can occasionally attack senescing faba beans and broad beans, particularly where rainfall has softened the pod.
Insect-damaged seeds are classified as defective beans and cannot exceed the tolerance level of three per cent.
Delayed harvest can often mean missing out on premiums being paid for early-harvested, high-quality crops. This is the case in some years, with the exception of seasons that encounter major production problems leading to a ‘shorts’ marketplace.
Weathering and mechanical damage are also more likely in late-harvested crops.
Early harvest also gives some degree of control over how and when the crop is marketed.
More information:Tim Weaver,
0427 255 086,
GRDC Project Code PAL00019