The Eleventh Regional Wheat Workshop For Eastern ... - Cimmyt

Reducing mechanical harvesting losses ofwheat - Dawelbeit
harvest the area in a period of one month is estimated to be about 300. Nonnally there is a
shortage and great efforts are usually made to bring combine harvesters from other agricultural
production areas.
Estimation of Wheat Harvesting Losses
Total wheat harvesting losses are generally divided into pre-harvest, gathering and processing
losses. Wheat yield is divided into collected yield and gross yield. The following definitions are
adopted:
1. Pre-harvest losses: These are the wheat seeds and spikes, which are lost on the ground and
can not be collected by the combine. The reason for this pre-harvest loss could be due to crop
lodging, weather factors such as wind or rains, or could be due to damage of wheat by pests such
as rodents or termites.
2. Gathering losses: These are usually wheat seeds and spikes that are missed by the combine
header and were lost on the ground. The main reason for gathering losses is combine operation.
Research results showed that gathering losses increased with over speeding and unskilled
operators.
3. Processing losses: Processing losses are those wheat seeds which are lost in threshing and
cleaning, broken seeds, unthreshed wheat heads and those lost with wheat straw. The main
reason for wheat processing losses is mal-adjustment of the combine harvester.
4. Total harvesting losses: Is the sum of pre-harvest, gathering and processing losses.
5. Collected yield: Actual weight of wheat harvested.
6. Gross yield: Is the sum of collected yield and total harvesting losses.
7. Percent losses: The ratio of the specific loss to the gross yield multiplied by hundred.
Minimizing Combine Harvester Losses Project
The project for minimizing wheat harvesting losses was started in the season 1993/94. The
organization involved establishing a higher committee for the project. Its responsibility is to
develop the annual work plans, establish committees in the different groups and to evaluate the
overall performance. Members of the committee included the senior staff of the agricultural
administration of the Sudan Gezira Board in addition to the agricultural engineering research
scientists at Gezira Research Station.
Before launching the project, literature was collected and two pamphlets were published. The
first was entitled "How to minimize wheat harvesting losses". It was written for fanners, and
included infonnation about: when to stop irrigating the wheat crop, signs of wheat crop maturity,
pH:;parations before harvesting, what to observe while the combine is working, and' what to
observe when the combine finishes its work. The second pamphlet targeted combine operators. It
was entitled "How to increase the efficiency of the combine harvester". It included instructions
of how to maintain the combine, workshop and field adjustments of the combine harvester,
patterns of combine harvesting, proper combine adjustments, critical factors of operation,
343