Maize: Best Practices During Harvest & Post-Harvest Stages

The market requires supply of quality maize in desired quantities at desired time, good quality maize attracts better market price that help farmers earn high income. Many times, farmers experience high losses of their quality maize right from harvesting to marketing.

It is estimated that farmers in Uganda lose up to 40% of their produce from harvesting to marketing as a result of poor post-harvest handling practices which leads to low quality of the maize. It is therefore crucial for farmers to adhere to good practices to maintain the quality of maize during harvesting and post-harvest stages.

HARVESTING

This is the process of detaching the maize cob from the mother plant after it has attained full physiological maturity. To ensure quality, harvesting should be carried out on time to avoid food losses and deterioration quality.

Maize is harvested at different physiological stages depending on the intended use. When it is for fresh eating, it is harvested when the cob is green and the grains are beginning to harden. If it is meant for silage making, the whole plant is harvested at milk stage, and when it is meant for grain, it harvested when it has dried and achieved full physiological maturity.

MAIZE PHYSIOLOGICAL MATURITY: Is that stage when the crop has achieved maximum growth.

METHODS OF HARVESTING: Maize can be harvested manually or mechanically;

MANUAL/HAND HARVESTING: This is the commonest method in Uganda and is considered practicable for crops of under 30 acres.

MECHANIZED HARVESTING: This is the harvesting of maize using machines (e,g combine harvesters) and is suitable for large commercial farms. Machines simultaneously harvest and remove ears, shells and do partial cleaning of the grain, it has an advantage of ensuring quality, reducing losses in addition to time and labor-saving.

COMMON PRACTICES TO AVOID DURING HARVESTING

1-Premature/early harvesting: this results into shriveled and rotten maize

2-Throwing cobs on the bare ground and use of dirty containers during harvesting. This increases risks of aflatoxin and other contaminants.

3-Late harvesting; this leads to attack of pests, loss of grain and rotting.

QUALITY CONTROL MEASURES

1-Harvest grains when they are physiologically mature

2-Harvest maize on time

3-Use clean containers/bags to collect the cobs during harvesting

4-Collect the cobs in the garden on a tarpaulin or mat.

POST-HARVEST HANDLING (PHH)

These are the activities carried out immediately after harvesting and they include transportation, drying, threshing/shelling. Packaging and storage, good PHH practices ensure that the harvested product reaches the consumers in the desired quality and quantity.

TRANSPORTATION:

Maize is transported home for other activities to be carried out. Transportation is done on head, bicycle, motorcycle, vehicles, depending on the volumes.

DRYING OF BEANS IN THE PODS:

This is the process of separating the maize grain from the cobs. The process makes grain available for utilization (processing, consumption and marketing). During shelling, measures to minimize grain damage and grain loss should be put in place. Cobs that are well dried are easily shelled.

METHODS OF SHELLING.

Hand shelling: Maize cobs are shelled using hands, it is slow and relatively painful on the thumb when large amounts of maize are to be shelled. For farmers using OPV seed, this is the best method since it does not damage the germ and it allows for sorting of seeds from the best cobs.

MECHANICAL SHELLING: Manual sheller is carried out using hand and peddle operated sheller. For the machine to perform optimally, the maize should be dry (13-14% MC). It is a low capacity tool used by the farmers that have very low volumes.

MOTORIZED MAIZE SHELLERS: They are powered by electrical mortars, they are stationed or mobile, imported or fabricated within the country. They can shell between 800kg-3000kg per hour. The mobile maize sheller have been designed to ease issues of accessibility. Using motorized shellers reduces post-harvest losses and hence more returns to the farmers. Use of motorized maize shelling has increased among farmers as a result of individuals especially youth adopting the technologies to offer shelling services as a business.

DRYING OF MAIZE

Drying is the systematic reduction of crop moisture down to safe levels for storage. It is one of the key postharvest operations that ensures maize grain quality. During harvesting the moisture content of grain is between 18-24 and this should be reduced to 12-13% for safe handling. During also reduces chances of rotting and germination of the grains.

SUN DRYING

Cobs are dried in open air on tarpaulin, drying yard, collapsible dryer, drying racks and in cribs. Note: It is recommended to use a maize crib because it protects maize grains from animal attack and against bad weather.

MECHANICAL DRYING

Hot air is blown in the grain to remove excessive moisture under controlled conditions. Hot air is generated using burning fuel, solar, electricity and biomass.

STORAGE TECHNOLOGIES

Various storage technologies (traditional and modern) can be used by smallholder farmers to store maize grain and these include;

TRADITIONAL TECHNOLOGIES

-Mud and wattle granaries

-Baskets

-Pots

-Jute bags

MODERN TECHNOLOGIES

Hermetic storage, OPV tanks/silos, metallic tanks/silos, cocoon, triple/pics bags, Warehouse, grain stores.

-Office of Agric Minister