Page 529 - Biosystems Engineering

Agricultur e Management 501

this hormone is given at a later stage, the insects become transformed
into giant larvae (immature adult) that die quickly.

Natural Insecticides Natural insecticides are extracted from plants
and sometimes from microorganisms. Alkaloids like nicotine from
tobacco (Nicotiana spp.) and pyrethrum from pyrethrum inflorescence
(Chrysanthemum cinerarifolium) are also used. Neem (Azadirachita
indica) is considered to be one of the most useful natural insecticides.

17.2.7 Harvesting
It is the process of collecting mature crops from the agricultural fields.
The cutting of grain for harvest is typically done by using a scythe, a
sickle, or a reaper. After harvesting postharvest handling begins
including cooling, sorting, cleaning, packing up for further on-farm
processing, or shipping to wholesale or consumer markets.
It has been suggested that an earlier harvest date may avoid dam-
aging conditions but might result in poorer yield and quality. Delay-
ing a harvest may result in a better harvest, but it increases the risk of
weather problems.
Harvesting involves various operations and varies from crop to
crop. It includes cutting, digging, picking, laying, gathering, curing,
transporting, and staking of crops. Cereals crops, such as wheat, rice,
and jawar are earheads containing grains, whereas most of the oilseed
and pulse crops have branches, which creates problems in harvesting
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by manual or mechanical means (Pranav and Pandey 2008).
Traditional Harvesting Methods
Crop harvesting is traditionally done with manual methods. Harvest-
ing major cereals, pulses and oilseed crops is carried out using sickles,
whereas tuber crops are harvested using country ploughs or spades.

Mechanical Harvesting
Timeliness of the harvest is of prime importance. Rains and storms
occur often during the harvesting season causing considerable dam-
age to the standing crop. Rapid harvesting also facilitates extra days
for land preparation and earlier planting of the next crop. The use of
machines can help to harvest at the proper stage of crop maturity and
reduce drudgery and operating time requirements. Considering these
factors, improved harvesting tools, equipment, and combines are
being adopted by farmers to use as a reaper. The invention of two
successful reaping machines—both independently by Obed Hussey
in Cincinnati, Ohio, who obtained the first patent in 1834. The first
reapers cut the standing grain and, with a revolving reel, swept it
onto a platform from which it was raked off into piles by a person
walking alongside (Fig. 17.6).