The document describes a new Aus-Aman cropping system for increasing cropping intensity in coastal Bangladesh. The system involves growing a short-duration aus rice during the pre-monsoon season followed by a high-yielding aman rice variety in the monsoon season. Supplementary irrigation using groundwater helps ensure the establishment of the aus rice crop. This new system can increase total annual production to 8-9 tons per hectare compared to the traditional single aman rice system, helping address food insecurity in the coastal region.

1. Aus-Aman cropping system: new approach for increasing cropping intensity in southwest coastal Bangladesh Sanjida Parveen Ritu, BRRI To Phuc Tuong, IRRI Manoranjan Mondal, IRRI Shahid Ullah Talukder, BAU

2. Coastal Zone Overview Coastal is the most impoverish part of the country, with low cropping intensity and low productivity caused food insecurity

3. Coastal Zone Overview Main constrain for agricultural production has been defined as Soil and water salinity lack of fresh water in dry season 1 mha land affected

4. Polder Construction vs Crop Production To overcome constrains to agriculture, in 1960 – 1970, GOB has built 135 polders with main mandate: control salinity intrusion and tidal surge Thanks to the polders, area and rice production in the coastal zone has increased

5. Cropping Systems after empoldering Main crop is still single aman (wet season) rice Aman – late Rabi (dry season nonrice) Changed cropping system (CPWF phase 1) in polder 30 Replace low yielding (2.5 t ha -1 ) local aman rice with high yielding varieties (5.0 t ha -1 ) Short duration aus (premonsoon season) rice and ensure their timely establishment HYV aus-HYV aman cropping system Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Traditional Rice (2-3 t/ha) Sesame (0.5-1.0 t/ha) Traditional Rice (2-3 t/ha)

6. Use of groundwater for supplementary irrigation will secure aus crop establishment On farm water management On farm storage Rainfall Long term Rainfall and evaporation pattern in Khulna district                                                    

7. New Cropping Systems 20 Apr 30 July 1 0 Aug 5 Dec River water EC5-15 dSm -1 River water EC 5-15 dSm -1 Rainfall ~1500 mm leaching down soil salinity Aus-Aman-Fallow Cropping System Groundwater EC 2-3dSm -1 River water EC < 2dSm -1 Rainfall and river water EC 0-2 dSm -1 3-4 t ha -1 4-5 t ha -1 T. Aman (130-140 d) Aus (100-105 d) A M J J A S O N D J F M A

8. New Cropping Systems 10 May 20 aug 30 Aug 20 nov River water EC5-15 dSm -1 River water EC 5-15 dSm -1 Rainfall ~1500 mm leaching down soil salinity Aus-Aman-Fallow Cropping System River water EC < 2dSm -1 Rainfall and river water EC 0-2 dSm -1 8-9 t ha -1 yr -1 20 May 20 aug 30 Aug 15 Dec 7-8 t ha -1 yr -1 T. Aman (~130d) Photosensitive Aus (100-105 d) A M J J A S O N D J F M A Aus (100-105 d) T. Aman (~140d) Nonphoto sensitive

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