Improving drainage is crucial for cropping intensification in the polderred

coastal zones of Bangladesh

To Phuc Tuong, IRRIManoranjan Mondal, IRRI

Sanjida Parveen Ritu, BRRIAbul Kalam Sharifullah, BARD

Elizabeth Humphreys, IRRI

New Cropping Systems Development• With new varieties

– Short duration– Non photoperiod sensitive– Salt tolerance

• Cropping systems research • On farm water management

– On farm storage– Rainfall

• It is possible to have 2 or 3 crops per year which can avoid salinity and overcoming the water shortage in the dry season

Sesame-Aman-F = 3-4 t/haBoro-F-Aman = 11-13 t/haAus-Aman-Rabi = 12-42 t/ha

New Cropping Systems

Boro (140-145 d)1 May

20 July

1 Aug

25 Nov

5 Dec

5 Apr

T. Aman (130-140 d)

Aus (100-105 d)

M J J A S O N D J F M A M

River water EC5-15 dSm-1

River water EC 5-15 dSm-1

Rainfall ~1500 mm leaching down soil salinity

Aus-Aman-Boro Cropping System

New Cropping System

10 Apr 30 June

10 July

15 Nov 1 5AprRabi (130-140 d)

1 Dec T. Aman (130-140 d)

Aus (100-105 d)

A M J J A S O N D J F M A

Rainfall ~1500 mm leaching down soil salinityRiver water

EC 5-15 dSm-1

River water EC 5-15 dSm-1

Aus-Aman-Rabi Cropping System

Constrains to New Cropping Systems

A M J J A S O N D J F M A

T. Aman (130-140 d)

Aus (100-105 d) Rabi (130-140 d)

Deep flooding at the beginning of rainy season constrains the establishment of aman rice and adoption of modern high yielding varieties

Prolonged water log at the end of rainy season delay establishment of rabi crop

High Tide

Low Tide

LandLand Surface

Embankment

River Bed

Sluice gate1-2 m

How to Adopt New Cropping Systems?• To realize the new cropping system, it is crucial to

improve the drainage of the polders• Can drainage be improved? Yes

2-3 m

• Previous role: salinity and tidal surge prevention

• Now with new cropping systems, the polders have additional roles– Water supply and storage – Drainage

• New function: polder has to be treated as one “water management unit”

Re-assess the Role of Polders in New Cropping Systems

Water Management in Polder: Institutional Level

• Various institution “manage” different part of the polder

• BWDB: construction and maintenance of the embankment and sluices

• BADC: small irrigation system within polders

• LEGD: outside polders

• No one looks at polder is a comprehensive water management unit

Conclusion• With advances in germplasm, on-farm water

management, it is possible to have 2-3 crops/year despite of salinity and water shortage in the dry season

• We have to improve drainage• Polders have been built 40 years, ago, with

the new cropping systems…..polders have new roles

• New roles need new management, new institution set up

THANK YOU