Thursday, 30 March, 2023
E-paper

Relay Wheat: A Step towards Greening Coastal Land

Dr. M. G. Neogi

Relay Wheat: A Step towards Greening Coastal Land
Dr. M. G. Neogi

Background:

The coastal region of Bangladesh represents around 47,211 square kilometers which is approximately one-third of the country where more than thirty-five million people are living. The coastal region is suffering from saline water intrusion, coastal land degradation, storm surges and drainage congestion due to high water flow and sedimentation in the flood plain.

The agriculture cultivation of entire coastal region is now threatened by climate change through increased salinity, high tides, water-logging, uneven rainfall, flood, drought, extreme heat, decreasing of winter season etc. through which Bangladesh is rated as the third most vulnerable country in the world.

Around 4 lakh 30 thousands (0.43 million) hectares of land remain fallow during dry season in coastal region of Bangladesh. Most farm households in the coastal region cultivate only one crop a year, i.e. long duration aman rice in monsoon from July to December. After harvesting the aman rice in December, most of the land lies fallow due to increased salinity in dry season and also scarcity of suitable water for irrigation.

Importance of wheat cultivation in coastal region

To feed its hungry people, food production in coastal areas during dry season must be increased by any means. The scope to expand wheat cultivation in wheat growing area of north-western Bangladesh is almost zero due to other competing crops like potato, maize, boro rice, etc. Thus, the fallow coastal belt in Bangladesh during winter dry season is the only area, where a crop like wheat could be introduced, as water requirement for wheat cultivation is low. Also during last three years field research in coastal saline fallow land under CIM-2014-076 project, it was observed that among cereals wheat has relatively salinity tolerant nature while its salt tolerant capacity is around 4-8 dS/m and only 2-3 irrigations are sufficient to complete its life cycle. 

Rice alone cannot meet the food requirements of the country. On the other hand, Bangladesh is becoming highly dependent on wheat importation as dietary preference is changing such that wheat is becoming a highly desirable food supplement to rice. Among the cereals, wheat is second to rice in economic and consumption importance. In last five years, wheat consumption has risen in the country which can be linked to increased population and changes in eating habits. Right now, Bangladesh imports around seven million tons wheat each year to cover local demand while production in the country is around 1.8 million tons from around 0.8 million hectares of land.

Wheat cultivation in changed climate

Although farmers in coastal areas cultivating rice mostly harvest in December, the optimum planting time of wheat in Bangladesh is in November. So it’s hard to sow wheat on time after the rice harvest. It is also be noted that climate changes lead to more frequent high temperature during the end of crop cycle, i.e. in February. It is estimated that maximum and minimum temperature for the month February has been increased by 0.62 and 1.540C respectively. It is also assumed that winter warming would be greater than summer warming. Also current assessment for Bangladesh by the IPCC predicts warming of 1.5-20C by 2050, with 10-15% increased rainfall due to climate change.

One option is to relay sow wheat into the aman rice field to ensure timely sowing of wheat in the month of mid-November and fully utilize the residual soil moisture.

Research on wheat cultivation in saline soil under ACIAR-CIM-2014-76 project during 2019-20

Before field research of relay wheat cropping in this year (2022-23), the project piloted wheat cultivation in the coastal region in 2019-20 as recommended by Bangladesh Wheat and Maize Research Institute (BWMRI). After harvesting of rice, seven farmers prepared their land and used recommended fertilizers and sowing seeds on 9 to 17 December 2019 at Hazipur saline soil of Kalapara upazila of Patuakhali district.  

After 93-99 days of planting, wheat was harvested on 14 to 20 March 2020 which was around 15-22 days earlier than normal harvesting time and yield was recorded around 3 ton per hectare. The highest yield was recorded from BAW 1147 line while the variety requires 99 days to harvest.

Research on wheat cultivation in saline soil during 2021-22

In 2021-22, the project again established another wheat block with 11 farmers at north Daulatpur village of Nilgonj union under Kolapara upazila of Patuakhali district. North Daulatpur comprises saline land, where 8-12 dS/m salinity is found during February-March. After harvesting rice, farmers prepared their land and sown wheat seeds like BARI Gom 33, BARI Gom 25, BARI Gom 30 and BAW 1147 on 25 December 2022 and then followed the BWMRI guidelines.

Due to rainfall in February this year, farmers required only two irrigations while they harvested crops after 86-94 days of planting from 22 to 30 March 2022 and received yield 2.4 ton per hectare. The highest yield was recorded from BARI Gom 33 and BAW 1147 line while the both variety requires 94 days to harvest. Compared to Hazipur village, north Daulatpur received less yield and less life cycle which might be for delayed planting and high salinity compared to Hazipur village.

Research on relay wheat cultivation vs. wheat cultivation (in general) during 2022-23

Based on last two years’ field experiments on wheat cultivation in coastal saline soil, this year (2022-23), the project established relay wheat cropping to avail optimum planting time of wheat as well as utilizing residual soil moisture in less saline soil condition. When aman rice becoming ripen and optimum soil moisture is available in saturated field condition, then seeds of wheat variety like BARI Gom 30 and BARI Gom 33 seeded in the aman rice field on 14 November 2022 as relay wheat cropping. The rice crop was harvested on 5 December 2022. BWMRI recommendations for wheat cultivation were followed in every step.

Side by side, the project also conducted wheat cultivation as normal practices after harvesting of rice to assess a comparative study between relay wheat in aman rice field and wheat cultivation after rice as usual. It is our observation that the performance of relay wheat is better than normal wheat cultivation in terms of vegetative growth, number and size of panicles formation, etc. Better performance of relay wheat which we are observing might be for the appropriate planting time in mid-November, through which, favorable temperature availed by the plant during its vegetative stage that falls in early January. Also due to less salinity during planting time has been favored for normal growth of wheat plant with sufficient formation of panicles.

As this is the only first year to conduct relay wheat in saline soil, we may need to conduct more trials in different saline areas of coastal Bangladesh to finalize the technology in a confirmed way.

 

The writer is the Deputy Project Leader of the University of Western

Australia. He can be reached at:

[email protected]