Harvesting is a critical operation as mistakes made at this stage can result in significant seed losses. Deciding on the correct time to harvest is dependent on your assessment of the ripeness of the crop.
Beans present no particular difficulties at harvest time. A mature standing crop can be harvested with minor adjustments to the combine.
Pre-harvest desiccation is unnecessary in a well grown crop of beans.
Desiccation may be worthwhile in weed infested crops or in late sown winter bean varieties that are ripening unevenly. Application should only be made when the crop is virtually ripe, i.e. when the stems are brown and the pods black.
The following chemicals may be used for desiccation in beans:
Using a desiccant to speed up ripening leads to yield losses; this will have little or no effect on harvest date or moisture content
When to Harvest
The crop is usually ready for harvest between late August and late September. The date of harvest is influenced by:
- Sowing date
When is the Crop Ready to Harvest
As the bean approaches maturity, all the leaves fall off, the pods turn black and then the stems turn black. The crop is ready for combining when 90% of the stems turn black. At this stage the seed will be hard and brown with moisture content in the range of 20 – 25%. Once all the pods have turned black, the crop is mature.
If you harvest before the stems turn black, you will get a dirty sample of seed with high moisture content
The crop is easily combined with only slight adjustments needed to the combine.
Concave: Open concave to avoid splitting the large seed.
Drum speed: Reduce drum speed to avoid splitting the beans. Beans are easily thrashed.
Fan speed: Use a high fan speed. The large heavy bean seeds are difficult to blow out of the combine. A good air flow will help produce a clean sample.
Beans are slow to deteriorate, even at a moisture content of around 23%. However, while there is no panic, they should be delivered to a drier within a few days. For longer term storage, beans need to be dried down to 14 – 15%.
Bean straw can be baled and fed to livestock. Alternatively, it can be spread and ploughed into the soil for the next crop.
Winter field beans will yield in the range of 3.5 – 6.0 t/ha. You should aim for a target yield of 5.0 t/ha.