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Rice plants - Seedlings are transplanted:
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Very young
-- usually just 8-12 days old, with just two small leaves
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Carefully
and quickly to have minimum trauma to the roots
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Singly, only
one per hill instead of 3-4 together to avoid root competition
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Widely
spaced to encourage greater root and canopy growth
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In a square
grid pattern, 25x25 cm or wider -- 30x30 cm or 40x40 cm, even
up to 50x50 cm with the best quality soil
Soil
This is kept moist but well-drained and aerated, with good
structure and enough organic matter to support increased
biological activity. The quality and health of the soil is the key
to best production.
Water
Only a minimum of water is applied during the vegetative growth
period, and then only a thin layer of water is maintained on the
field during the flowering and grain filling stage. Alternatively,
to save labor time, some farmers flood and drain (dry) their
fields in 3-5 day cycles with good results. Best water management
practices depend on soil type, labor availability and other
factors, so farmers should experiment on how best to apply the
principle of having moist but well-drained soil while their rice
plants are growing.
Nutrients
Soil nutrient supplies should be augmented, preferably with
compost, made from any available biomass. Better quality compost
such as with manure can give additional yield advantages. Chemical
fertilizer can be used and gives better results than with no
nutrient amendments, but it contributes less to good soil
structure and active microbial communities in the rhizosphere than
does organic matter. At least initially, nutrient amendments may
not be necessary to achieve higher yields with the other SRI
practices, but it is desirable to build up soil fertility over
time. Rice-root exudation, greater with SRI, enhances soil
fertility.
Weeds
Since weeds become a problem in fields that are not kept flooded,
weeding is necessary at least once or twice, starting 10-12 days
after transplanting, and preferably 3 or 4 times before the canopy
closes. Using a rotary hoe -- a simple, inexpensive, mechanical
push-weeder has the advantage of aerating the soil at the same
time that weeds are eliminated. (They are left in the soil to
decompose so their nutrients are not lost.) Additional weedings
beyond two increase yield more than enough under most conditions
to justify the added labor costs.
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