Sweet watermelon turns sour amid climate change

Context:

Watermelon cultivation in salinity-affected coastal Bangladesh exacerbates drought-like situations.

• Switching from shrimp aquaculture to mixed agriculture, farmers resort to lucrative watermelon farming. 
• Depending on irrigation with harvested rainwater, watermelon farming creates an acute water crisis in the warm summer. 
• Watermelon farming itself is affected by erratic rainfall. 

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Experiencing a gradual production loss on his decade-old shrimp farm, small-holder farmer Nirmal Gayen initiated watermelon cultivation three years ago.  

So far, Nirmal’s watermelon project at Dacope sub-district of Khulna, has not disappointed him. This year, he sold watermelons worth Tk140,000 ($1,181)—almost three times his invested money. Six years ago, when he last cultured shrimps, he invested Tk60,000 ($705) but could only fetch half of that amount.  

However, Nirmal discloses the flip side. “This area faces a severe water crisis during summer. Whatever little water remains available, we use it for irrigating our watermelon fields. But sometimes, even that becomes unmanageable,” he says.  

This brief story of Nirmal is a testimony of how farmers, particularly in Bangladesh’s salinity-hit southwest region, have been changing crops, partially because of climate change, only to find out that the solutions are either causing or suffering from other problems – some also related to climate change.

 

Switching livelihoods to adapt salinity 

The Bangladesh Bureau of Statistics has estimated that around 246 thousand households, or approximately 1.2 million people, are vulnerable to salinity. In 2021, around 5,018 hectares were found exposed to salinity.  

For years, salinity has been the common enemy of agriculture in southwest Bangladesh. The Dutch-style polders or dykes, built in the 1960s to protect farmland from salinity intrusion, were initially effective. 

However, the commissioning of the Farakka Barrage on the Ganges River exacerbated salinity issues, as it started to reduced water flow, particularly during the dry season, in the major distributaries in the southwest region. 

Back in the 1980s, commercial shrimp farming began in the southwest region because it appeared convenient to cultivate in intensified salinity. However, this led rice farmers to shift to shrimp as increased salinity restricted rice production throughout the year in the particular region. 

Nirmal—inheriting the rice farming profession by generations—had no option but to convert his land into a shrimp farm, as did all of his neighbouring landowners. 

“I couldn’t protect my land from salinity. Rice didn’t grow there anymore. How would I survive without income? So, I also started shrimp farming,” Nirmal recalls the difficult time. 

 

Shrimp farming was initially beneficial for more than a decade. But it seems now more difficult, possibly due to climate change.

According to the Nationwide Climate Vulnerability Assessment in Bangladesh, high temperatures trigger virus attacks and mortality in shrimp farms, while too low temperatures slow shrimp growth.

Several studies have identified high temperatures, floods, erratic rainfall, low temperatures, and cyclones as climate change impacts in Bangladesh’s shrimp farming zones.

Professor Ghausiatur Reza Banu at fisheries and marine resources technology discipline under Khulna University, says, “Climate change-induced high temperatures with coastal humidity allows virus attacks in saline-based shrimp farms.”  

Welcoming watermelons to overcome salinity 

To avoid income loss, many shrimp farmers have been adopting mixed agriculture, like rice-watermelon and rice-vegetable, as a means of adaptation, researchers noticed in 2018, after studying tendencies in six coastal districts including Khulna. 

According to their study, rice-watermelon agriculture generates a gross benefit of Tk220,000 ($1,843) and a net income of Tk69,000 ($578) on average per hectare, which are 22% and 21% higher, respectively, than those from shrimp production. The outcome of rice-watermelon is also higher than rice-vegetable. 

“My shrimp farm was loss-making. Now I am profiting from producing watermelons,” Nirmal says, adding that he has doubled his land coverage for watermelon farming to a 4,040 square metre plot than what was for the shrimp culture. 

 

Watermelon, as a cash crop, has been cultivated all over Bangladesh. But only five coastal districts—Khulna, Patuakhali, Barguna, Bhola, and Noakhali—produced 92% of national watermelon production in the 2022–23 fiscal year.

In that period, the districts produced 3.3 million tonnes of watermelon on 83,095 hectares. The production and land coverage were almost three times the amount in the 2018-19 fiscal, according to the Department of Agricultural Extension .

Department of Fisheries data shows that the five districts produced around 30 thousand tonnes of shrimp in the 2018-19 fiscal year. By 2022–23, shrimp production dropped by over 7%, with shrimp aquaculture coverage decreasing by almost 5% in the districts.

Hironmoy Roy was one of the organisers of farmers who protested against aggressive shrimp farming in Dacope. The rapid expansion of shrimp aquaculture was seen as a dominant stressor on local agriculture-based livelihoods, as wealthy landowners resorted to hostile land grabbing  amid increased demands for available land and water bodies for shrimp farming.  

 

This year, Hironmoy and his three partners harvested over 51 tonnes of watermelons on a 1.48-hectare land.  

For the last couple of years, farmers like Hironmoy have been cultivating Aman rice during the monsoon, planting between July and August and harvesting by December. In January, they prepare the same land for watermelon, which they harvest in April.

“Switching from shrimp to rice-watermelon farming facilitates agricultural activities almost year-round, which has had a positive impact on the local economy,” Hironmoy says.

Changing rainfalls affect rice-watermelon culture

However, switching to rice-watermelon as a solution to aggressive salinity has not been a perfect silver bullet. Changing rainfall patterns have had an impact on the production of crops as well. 

In the southwest floodplains, summertime soil salinity increases far beyond what growing paddy can tolerate.  

“That is why rice farmers wait for peak monsoon so that continuous runoffs leach the concentrated salts from topsoil,” says Dacope sub-district Agricultural Officer Shafiqul Islam. 

But peak monsoon is also changing, delaying the crop calendar of the region. 

 

“The peak monsoon in the region has been gradually shifting from June to July. This is a manifestation of climate change,” assesses Professor Mohammad Shamsudduha at the Department of Risk and Disaster Reduction under University College London, United Kingdom. 

Some coastal farmers inform us that, in recent years, they have been resuming Aman rice cultivation in August instead of July and harvesting the crop in January.  

“Because of this, we have to prepare the watermelon fields in the last week of February. As a result, watermelons mature after the first quarter of April,” says Kamal Mollah, a farmer organiser at Kalapara of Patuakhali district 

April is Bangladesh’s warmest month, featuring also nor’wester with heavy rains, thunderstorms, and occasional hailstorms.

 

Analysing dry season rainfall patterns and crop production in coastal Bangladesh, some researchers have traced that heavy (10+ mm) and very heavy (20+ mm) rainfalls in November-December and March-April caused delayed non-rice crop planting.

According to their study, heavy rains in November 2016-17 and December 2017-18 delayed watermelon planting until January, exposing crops to high temperatures and salinity stress and leading to crop loss at a significant amount. 

“Traditionally, the regional farmers cultivate late-maturing Aman rice. Amid the erratic rainfalls, they sometimes struggle with non-rice crop farming,”Md Maniruzzaman opines. Maniruzzaman is one of the authors of the study. 

 

Watermelon is creating water scarcity

Despite the challenges, watermelon farming has brought solvency to farmers. But this has come at the cost of an acute water crisis.

Nirmal’s wife Kamala Gayen, also a farm labourer, struggles hard to manage water for her household chores, including rearing cattle and poultry. Because this fruit farming draws fresh water from the neighbouring canals and rain-fed ponds, creating a drought-like situation. 

“Amid an acute water crisis, we cannot provide adequate water to our animals,” Kamala says. 

In the coastal region which is one of the most vulnerable areas in terms of access to safe drinking water in the country, women are primarily responsible for collecting freshwater for their families. 

Usually, they collect domestic usable water from rain-fed ponds and drinking water from harvested rainwater-filled tanks they own. 

All the existing options are fully dependent on rainfall while 80% of the total rainfall occurs only in the June-September period. 

“Our harvested rainwater in the tanks doesn’t last beyond 3-4 months of storage. The rest of the time, we depend on either purchased water from a nearby NGO-operated reverse osmosis plant or purified pond water,” Kamala says. 

 

In late September farmers snapped the canals’ connectivity to intertidal rivers by temporary embankments, restricting saline water intrusion into the crop fields. The reserved water is later used for irrigation in the dry season. 

While starting watermelon farming, farmers plough the fields and clear them of fibrous roots and remnants of paddy plants. 

Ten days later, watermelon seeds are planted, and water is given every three days. Once the seedlings sprout, the fields are watered once a week. 

As the plants grow during their vegetative, flowering, fruiting, and ripening periods, farmers increase the volume of irrigation. 

“The peak irrigation demand is created in April when canals dry up, and we have no other option but pond water for every purpose,” Kamala laments. 

 

Abdullah Al Mahmud, Dacope Public Health Engineering Department’s sub-assistant engineer, has observed that local communities struggle to manage water for household chores as expansive watermelon cultivation absorbs water from the reserved freshwater canals and rain-fed ponds. 

“Many insolvent families, fully dependent on rain-fed ponds and unable to purchase large tanks for restoring rainwater, suffer water shortage the most,” Mahmud says. His department is responsible for ensuring safe drinking water in the locality.

Supervisor of the 2018 study, Professor Abdullah Harun Chowdhury teaches environmental science at Khulna University. He is concerned about the inconsideration of the environmental impacts of watermelon farming.

“Watermelon has been cultivated extensively without prior assessment of the availability of irrigation water, and its negative impacts are now evident,” Chowdhury says. 

Although having lower literacy, experienced farmer Nirmal presumes that shrimp aquaculture faced downfall as it was not carried out considering the environmental issues.  

“I fear that watermelon cultivation similarly would become unprofitable someday,” Nirmal concludes.

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This story was produced with the help of the Thomson Reuters Foundation. The content is the sole responsibility of the author and the publisher.