Maize can be harvested either green or dry.
Green maize is harvested for roasting or boiling.
Maize takes between 3- 8 months to mature depending on variety and weather condition.
- The leaves and husks starts to dry out
- The part of the kernel where it is attached to the cob starts to turn brownish or blackish in 90% of the kernels of the cob. This is called black layer formation
- The cobs are no longer appreciated for roasting
- Upon breaking a kernel the inside of it is no longer milky
- At least a quarter of the cobs have started to droop
- Moisture content is about 35%
Cutting, stooking and dehusking
It can be done manually by removing cob by cob or by cutting the stocks together with the cobs and stooking in the field to dry further.
Stooked maize may take 1-3 weeks to dry depending on weather condition after which cobs should be picked off (dehusking) and stored. Stooking allows ploughing for the next crop to be done between stooks.
In-field drying can be supplemented by drying the cobs in improved drying structures (well ventilated cribs) and this reduces the risk of development of moulds.
The cobs can be brought out the cribs spread on mats or trays and exposed to solar radiation to ensure complete drying to the required moisture content for shelling.
Shelling should be done when the maize has a moisture content of 13-14%. Shelling by hand is the most common method. Other types of hand tools and machines are used to making shelling easier and increase capacity. Maize is shelled for the following reasons:-
- Mixing with insecticide is easier and more efficient
- More accurate application rates of insecticide is attained
- Prolonged Shelf life of the Shelled grain
- Less space is required to store shelled grain (volume is reduced by 25-40%)
- It is easier to control and inspect the produce
- Rodents may burrow in cob maize but cant cause significant damage below a surface grain
Once shelled, the maize should be cleaned by winnowing and then treated with the recommended chemical insecticides like Actellic Super (at 50g per 90 kg bag)
- Dried maize can be stored either in cobs or shelled.
- It can be stored in bins, silos, cribs, or in sacks. Sacks should be raised off the ground to allow air circulation
Refer to on recommended varieties by zone