rice today vol. 13, no. 3 a never-ending season

8/12/2019 Rice Today Vol. 13, No. 3 A never-ending season

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3/414 Rice TodayJuly-September 2014

A thirst for growthWater is critical to future growth

but the planets fresh water cansustain only so much growth.In 2014, an unusually early dryseasonand the diversion of waterto the Three Gorges DamcausedChinas Poyang Lake to dry up,threatening a million peopleliving in surrounding areas withwater shortages. The costs of lostlivelihood and ecological damageare staggering. What makes thistruly alarming is that Lake Poyangis Chinas largest freshwater

laketwice the size of London! Ifthe water sources that feed majorrice production sites in Asia wereto run dry, the impact would becatastrophic.

Intensive rice cropping ispossible only because we havesufficient water for irrigation, saidTeodoro Correa Jr., who manages thedaily operations in the LTCCE. Wecannot do this in the event of severewater scarcity in the future.

In 2012, the LTCCE adoptedalternate wet and dry (AWD)

irrigation. This is a watermanagement system in which ricefields are not kept continuouslysubmerged. Instead, it allows fieldsto go without irrigation from 1 toup to more than 10 days (as long aswater levels do not drop below 2cm) before flooding the fields again.This reduces water use withoutsignificantly affecting rice yieldand has been successfully used inBangladesh and Indonesia.

We know that continuous

flooding preserves the organicmater content of the soil even withintensive cropping, said Mr. Correa.How will AWD affect soil fertility?That remains to be seen.

Adjusting the flooding paternswith one or more dry periods couldmaintain the overall organic materof the soil at a fairly stable level. Butit will take at least 5 years for theLTCCE to collect the necessary datato verify this.

Too hot for comfortThe LTCCE has also shown that

yields since 1992 have varied fromyear to year. And, insect pests anddiseases have not affected riceyields because the varieties grownin the LTCCE are regularly replacedwith new high-yielding ones thatare pest- and disease-resistant.Rice yields are higher in years andseasons with abundant sunlight,yet yields have dipped during thedry season (from January to April)when rice is supposed to producemore grains. Both Dr. Buresh and

Mr. Correa are looking skyward forpossible explanations.

Rice is sensitive to sunlight,said Mr. Correa. Rice plants yieldlower during the wet season becauseof overcast skies. But we have notedhaving more cloudy days duringthe dry season. Climate experts

believe that the increasing globaltemperatures will cause greaterevaporation of water, mainly fromoceans, into the atmosphere and this

The LTCCE is dedicated to investigating the bestmanagement practices for sustainable farmingfrom theearly days of the Green Revolution to production modelsusing upcoming technologies.


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rice today vol. 13, no. 3 a never-ending season

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