(IPPM) in Vegetables - Vegetableipmasia.org

Resource Manual on IPPM in Rice
World Education Philippines, Inc.
capability of the farmer and other environmental factors particularly rainfall. The
insufficiency of rainfall which limits potential yield for example, leads to low
efficiency of fertilizer use.
The kind and amount of nutrients to be applied to the crop on a given soil can be
determined either by field experimentation, soil chemical analysis, plant analysis,
observations of deficiency symptoms or a combination of these methods. Field
experimentation is the most reliable biological method known. Soil and plant
analyses are more effective if used in conjunction with field experimentation
while the use of deficiency symptoms requires considerable experience and
expertise.
2. Timing of Nutrient Application
Fertilizer should be applied at the proper time to minimize loss of nutrient
particularly N and to maintain adequate supply of fertilizer nutrients when plants
need them to ensure profitable yield.
If the crop absorbs high proportion of nutrients added as fertilizer efficiency
automatically increases. This means that fertilizer efficiency can be increased by
getting higher yields with the same amount of nutrient absorbed by the plant. One
way to achieve this is to apply the fertilizer at a time to best meet the demand of
the rice plant.
Rice plants of medium growth duration (145 days), when grown at low N levels
(about 20 kg/ha), use fertilizer most efficiently for grain production during the
maximum tillering stage and around the flowering stage (between booting and
milking stages). A high nitrogen supply tends to decrease the number of filled
spikelets and the weight of 1000 grains. Therefore, split application of N, with one
dose at transplanting and another panicle initiation is best for obtaining high grain
yields, particularly in the case of medium-season and long-season varieties. N
absorbed by the plant from tillering to panicle initiation tends to increase the
number of tillers and panicles, and those absorbed during panicle development
(from panicle initiation to flowering) increase the 1000-grain weight. The effect of
nitrogen topdressing at the early panicle initiation stage on the patterns of N
uptake by rice plants almost resembled that of a high level of basal dressing of N.
Two to three applications of N per crop give the highest nitrogen efficiency and
that more split applications are needed for long-duration varieties and for lighter
soils.
Rice, like any other cereals requires a considerable quantity of P for vigorous
growth and high grain yield. P is applied to rice at planting. Later application can
be made provided it is not later than the time of active tillering. Early application
of P is essential for root elongation. P applied during the tillering stage is not
efficiently used for grain production. Split application of phosphorus has not been
proven of value because, first, there is a great mobility of phosphorus from old
leaves to young ones; second, the availability of soil P increases with time during
submergence; and third, because leaching losses are low.
Generally, the response of rice to K added to the soil is not as marked as for N or
P. There are reports that most rice soils in Asia do not need K as much as N and P
and that only a small and variable increase in rice yield is obtained with additional
potassium fertilizer.
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