Bradbrook - 2012 - Rice Farming complete with methods to increase ric

7. The Economic Threshold
The economic threshold is a concept used by farmers in deciding whether or not to
apply pesticides when a pest incidence is detected in the field. The level of pest attack
is first assessed and based on the estimated cost of treatment, the farmer determines if
the benefits of applying the treatment (yield value after damage) can cover the cost of
that treatment. Methods used to assess the level of pest attack include number of
insect pests per 10 plants, percentage of plants harboring a disease in a given area, or
the number of weeds in a one-square-meter area. Once the level of pest attack has
been determined, then the cost to apply the treatment can be calculated. The farmer
then determines how much can be earned from the reduced yield with and without the
pest treatment. The economic threshold is expressed as a percentage of crop loss using
the following formula:
% crop loss necessary for treatment to be worthwhile = [C/YP(K/100)] x 100%
Where:
C = the cost of treatment,
Y = the expected yield of the crop,
P = the expected price per ton, and
К = the expected effectiveness of the treatment
For pest treatment to be justified, the percentage yield loss without treatment must be
greater than the percentage crop loss necessary for treatment to be worthwhile.
Part 12: Harvest
The best time to harvest rice is when 80 to 85% of the grains have ripened (i.e. they are strawcolored),
with the remaining 15 to 20% in the hard dough stage. Fully ripe grains will have a
moisture content of between 20 and 25%. On average, grains are ready for harvest 30 days
after flowering. Rice varieties differ in the number of days to harvesting from sowing.
Generally, early-maturing varieties take 110 days, average-maturing varieties take from 113
to 125 days, and late-maturing varieties take from 130 to 136 days. The days after heading
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