Chickpea - harvesting and storage

A field of chickpea plants

A field of chickpea plants

Chickpea harvest can often clash with wheat harvest and traditionally wheat has been given priority due to potential quality premiums. However, this needs to be balanced with the relatively higher value of chickpea and potential losses that can result from a late chickpea harvest. Chickpea yields average approximately 70% of wheat yields when sown in an identical situation.

The use of specialised headers and separate storage facilities for chickpeas may alleviate the competition with wheat for time, labour and equipment usage. Harvest timing will depend on the moisture content that is acceptable for delivery or storage. This will depend on who is buying the grain, or whether aeration is available in the storage. A general rule is that harvest should be under way when upper pods are 15% moisture, if aiming to deliver at 13-14%.

Receival standards for chickpeas have recently been revised, with the maximum moisture now increased to 14% for grower receivals. Harvesting grain at 13-15% moisture content will help minimise cracking. Above 14% moisture, the crop should either be aerated or dried. Aeration is usually very effective in pulling chickpea moisture content down several percentage points.

Planning for an early harvest

Chickpea plants are indeterminate and the period of flowering can extend anywhere from 20 to 50 days depending on levels of flower abortion and the impact of moisture stress on the plant. Early or timely harvest of the chickpea crop has the potential to increase returns by up to 50%. Management to ensure timely harvest consists of a combination of strategies.

Paddock selection and agronomy

Planning before and during sowing can reduce many harvest difficulties. Paddock selection will determine the risk of disease, waterlogging, weeds and poor establishment, ultimately influencing crop maturity. Sowing method and row spacing will affect evenness, crop height and lodging potential. All of these factors can affect the ease and timeliness of harvest.

Disease and insect control

Botrytis grey mould can be a common disease at flowering, particularly in crops that have canopied over. Botrytis causes flower and pod abortion extending the growing period and delaying maturity by up to six weeks. Crops need to be monitored closely at flowering. Ascochyta blight, if not controlled during grain filling, can lead to high levels of lesions on the seed, resulting in downgrading and marketing difficulties. Heliothis may cause delays to harvest by attacking pods and extending the flowering period when the plant compensates for the lost pods (this is unlikely to be a problem under normal conditions where good insect control is practised..

Desiccation

Desiccating a crop overcomes problems with green weeds at harvest and improves harvest efficiency by eliminating many of the problems associated with green stems and gum build-up, such as uneven feeding and drum chokes. Minimising these problems enables drum speeds to be reduced in many cases, with a reduction in cracked or damaged grain. It allows harvesting of a crop that will not naturally shut down due to high soil moisture, and stops chickpeas reshooting and reflowering after preharvest rain, and makes crops with uneven maturity more uniform, allowing earlier harvesting.

Timing of desiccation:

The optimal stage to desiccate the crop is when the vast majority of seeds have reached physiological maturity i.e. 90-95% of the crop. Our best guide at the present time is to base this on a visual inspection of the seeds within the upper 20% of pods on each main fruiting branch. Seeds are considered to be physiologically mature when the green seed colour begins to lighten, normally when the pod wall begins to yellow. For an easier determination and to avoid the need to inspect seeds, the current advice is to desiccate when 80-85% of pods within the crop have turned yellow-brown.

Effect of desiccants on immature seeds: Desiccants should not be applied too early as they can affect green seeds. The result can be a reduction in grain size and yield, an increase in immature seeds, and a reduction in seed viability.

Registered desiccants

Chemicals registered for desiccation in chickpeas (as of May 2009)
Active Example product name Rate/ha Days to harvest
Diquat (200g/l) Reglone 2-3L 2 days
Metsulfuron + glyphosate (540g/L as potassium salt) Ally + Roundup PowerMax 5g + 0.5-1.1L 7 days
Glyphosate (540g/L as potassium salt) Round-up PowerMax 0.68-1.8L 7 days

See also Chickpea - weed management for herbicides and tables

Harvest timing and technique

Chickpeas have traditionally been harvested after wheat. This practice needs to change, as the costs of delaying chickpea harvest may be considerable.

  • Yield losses are due to pod drop as weathering weakens the hinge attaching the pod to the stem.
  • Weathered pods become more difficult to thresh, resulting in grain loss in unthreshed pods out the back of the header, cracked grain and a slower harvest.
  • Increased lodging - the risk is higher if the crop is high yielding and has been planted on wide rows.
  • Harvesting at 8% moisture instead of 13% results in a harvest weight loss equivalent to $25/tonne. Farmer experience has shown yield losses of up to 30% if harvest is delayed 2-4 weeks.
  • Weathered or drier grain is more likely to crack when handled, increasing the amount of split grain in the sample. The number of unthreshed pods in the sample will increase, as they become harder to thresh with weathering. Both of these can result in rejection or the need for grading to meet market requirements.
  • The germination rate and vigour of planting seed will be reduced by weathering. Crops intended for seed are best harvested at 14-16% moisture and dried or aerated back to 12% moisture to maximise both germination and vigour.
  • Chickpea grain discolours and darkens with weathering, reducing its desirability, particularly in the container market.
  • Chickpea prices can reach peaks during harvest to meet shipping schedules. Earlier harvesting may allow access to these opportunities.
  • Darker, weathered seed may be discriminated against in the market.
  • Ascochyta can infect senescing pods under wet conditions, leading to infected and discoloured seed.

Late harvested crops, particularly where there is regrowth, can be a major source of heliothis migration into neighbouring summer crops.

Harvesting tips and tools

Header modifications and settings

Draper Fronts (i.e. MacDon or Honeybee) have become increasingly popular. The centre feed draper platform provides uniform crop flow into the header, with minimal crop loss, and little damage to the seed. The cutter bar design allows for both vertical and end table flotation. While their contour following ability is not quite as good as a floating cutterbar, they have performed very well, provided the paddock is relatively level. Operators claim they can be operated at higher travel speeds than a conventional front in chickpeas.

Preferred air front setups

Air fronts help to reduce shattering losses, and minimise the amount of soil and other debris (stubble, sticks) in the final sample. Where soil contamination is likely to be a problem, fit perforated screens to replace the feeder house floor, elevator doors, and clean grain cross augers. Twin blowers may be necessary on fronts wider than 7.6 metres.

Harvest-Aire or other air fronts are generally considered better than batt reels as they minimise the risk of pods detaching from the plant. They improve feed-in over the knife section, reduce soil, sticks, rocks and stubble contamination, and allow the operator a clearer view of the cutting platform. Adjustment of the angle and height of the air nozzles is critical, and may need adjustment as crop conditions change.

Fitting a Vibra-Mat improves the flow of material over the knife-section and along the platform. They are relatively cheap with a low maintenance cost.

Fit cast, short crop fingers, and if using a closed-front, the fingers will need to be spaced 19 mm or more apart. Fitting double density Kwik-cut knife guards will help reduce plant vibration and reduce the risk of pods detaching from the plant. Do not use in an un-desiccated crop and/or if there is a lot of green weed present as jamming will occur.

Check that the header front is level, and not higher at one end than the other. Set the knife at the correct angle for short crops, and install a simple depth gauge.

In short crops where soil contamination is likely to be a problem, fit perforated screens under the platform auger and/or broad elevator. Fit screens to repeat and clean-grain cross augers. Floating or flexible cutterbars can be useful in short crops.

Conventional headers

Cracking is minimised with conventional heading set at 300-500 rpm. Adjust upwards if jamming occurs in un-desiccated crops.

A concave clearance of 10-30 mm depending on seed size is required. Check the concave for uneven clearance. Standard concaves tend to bow in the centre when fully loaded, and may need strengthening or replacement (i.e. with a Loewen concave). Removing alternate wires and the blank-off plates from the concave will also help reduce cracking. If possible cover the rasp bars with plate.

Reduce speed of the beater to 100% of drum speed (wheat is usually set at 150%).

Fan speed should be set at 80-100% of maximum. The relatively heavy weight of individual chickpea grains allows the use of high air flow.

Sieves

Set sieves to suit the grain size of the chickpeas being harvested. This is more critical than for wheat. Set the top sieve at 20-25 mm. AB and D Airfoil, non-adjustable top sieve is reported to work well in chickpeas and increases overall sieving capacity. The bottom sieve should be set at 12-16 mm. The bottom sieves can be altered so that the front 400 mm can be adjusted separately from the rear section. This allows the front section to be left open, and more air can be directed through onto the top sieve if required.

Header speeds

A maximum speed of 8 km per hour is recommended. If using a batt reel, it should be set at the same speed as the header.

Grain handling and storage

Grain may be handled up to six times before delivery to receival points so it is important that growers minimise the number of handling stages wherever possible and use efficient handling techniques that minimise damage, such as belt conveyors rather than spiral augers. However, if using augers:

  • operate slow and full
  • use large diameter augers
  • the length of the auger should be no longer than is necessary
  • keep auger incline low
  • check flight casing clearance. Optimal clearance is typically 50% of grain size to minimise grain being wedged between the auger spiral and the casing.

Storing chickpeas

Growers contemplating medium to long term storage (6-12 months) need to be aware that chickpeas continue to age, and that quality deteriorates over time. Desi chickpeas will darken considerably and seed germination and vigour will decline in storage. The rate of quality decline is accelerated by high seed moisture content, high temperatures, high relative humidity, and condition of the seed at harvest.

Seed subject to field weathering prior to harvest will deteriorate quicker in storage, even when stored under acceptable conditions of temperature and relative humidity.

The maximum moisture content (% wet basis) for minimal deterioration of Amethyst seed colour when stored at two temperatures and two storage times. (CSIRO Stored Grains Research Laboratory)
Temperature 20 °C 20 °C 30 °C 30 °C
Duration 3 months 9 months 3 months 9 months
Moisture 14% 13% 13% 12%

To maintain colour and minimise darkening of seed, any grain stored above 12% moisture will require cooling.

Maintaining quality during storage

Paint the outside of the silo with white paint. This reduces storage temperature by as much as 4-5 °C and can double the safe storage life of grains. Aerate silos with dry, ambient air. In addition to reducing storage temperatures, aeration is also effective in reducing moisture of seed harvested at high moisture content if flow rates are sufficient. Growers should avoid even short-medium storage of weather-damaged grain.

Effect of moisture content and temperature on storage life of chickpea seed
Storage moisture (%) Storage temperature (°C) Longevity of seed (days)
12 20 more than 2000
12 30 500-650
12 40 110-130
15 20 700-850
15 30 180-210
15 40 30-50

Note: most planting seed will need to be stored for a period of 180 days or more.

Insect pests in storage

Insects are not considered a major problem in stored chickpeas. The only exception appears to be in cases where chickpeas are loaded into storages containing residues of cereal grain already infested with rust red flour beetle, lesser grain borer, or saw toothed grain beetle. Where a prior infestation already exists in the storage structure, then it can develop and spread in the chickpeas. The key to control is to ensure that all handling equipment and storages are cleaned of old cereal grain before they are used to handle chickpeas. After cleaning, Dichlorvos can be used to disinfect storages provided they are left empty for at least two months before chickpeas are stored. If insects are found in stored chickpeas, the only registered treatment is prosphine fumigation. Adult insects are generally easy to kill, but immature stages and resistant strains can only be controlled in a sealed, gastight storage. Read the label for instructions on handling grain after fumigation. Good hygiene combined with aeration cooling should prevent insect infestations developing.

Bruchids

Growers in central Queensland need to be aware of the potential risk of bruchid infestation if storing chickpeas over the summer period. (i.e. planting seed ). Hygiene is the most cost effective methods of managing the Bruchid problem. Growers need to thoroughly clean all residues of other grain legumes from headers, planting equipment, shed floors, augers and empty trucks and storages after each harvest, and whenever legume seeds are handled on the farm.

Further information

Last updated 26 July 2012