Tuhin Mondol, 26, picks up a dried lump of earth in his hands. It crumbles between his fingers and falls to the ground. “This is how you tell the soil is saline. Normal soil won’t crumble like this,” he says.
He owns 13 bighas of land in Shibpur village, Dhablat mouza, Sagar Island, where he grows paddy, potato and onion along with his father Ajit Mondol, who has been farming the same land for more than 40 years.
In recent times, saline soil has wreaked havoc in his land by reducing produce. He says it all started with a series of extreme weather events — first super cyclone Aila, followed by Phani, Bulbul and Amphan — that have mostly rendered his moderately fertile land saline and uncultivable.
Mondol isn’t the only one. As low-lying regions like the Sundarbans become increasingly vulnerable to climate change-induced rising seas and more frequent storms, the communities who depend upon this land for survival face newer threats, with sea-level rise and coastal erosion increasing salinity of the soil.
Impact On Agriculture
Sagar Island lies about 100 km south of Kolkata and is part of the Sundarbans delta region. Agriculture and fisheries are the main occupations of the people of this island. The island also has religious significance. Every year, hundreds of pilgrims make their way to the island to take a dip in the holy waters of Ganga Sagar. Locals say they have been witnessing the quality of the soil and the agricultural yield from it decreasing for a while.
Renuka Maity, 31, is a small farmer residing in Mahendraganj village in the northern portion of the island. She is also the midday meal supervisor at a local school and the leader of a local self-help group. For years, she has been hearing about the degradation in yield from members of the SHG.
The paddy plants started developing a reddish colour and died. Sometimes, the plants would get uprooted by the breeze. The yield from the plants that managed to survive was low. “The rice did not taste good. Even the cattle refused to eat the crop refuse from the paddy,” she says.
Due to climate change, the island and other nearby areas have experienced frequent storms, storm surges, heat stresses, inland and coastal flooding. The intrusion of saline seawater during cyclone Aila in 2009 not only destroyed the standing crops but degraded the soil to such an extent that the lands were left barren for nearly 5 years.
Salinity in soil has hampered agricultural production in Sagar Island for many years now. Saline seawater is increasingly breaching the mud embankments during high tides and contaminating the soil and water sources.
Experiments With Salt-Tolerant Varieties
As the local farmers went through the motions of poor yield and dying plants, Paribesh Unnayan Parishad, a local NGO led by a former scientist, gave her some traditional variety of paddy seeds and asked her to sow those instead of the high yield variety (HYV).
The plants from these seeds were not only healthy but also gave good yield. “Previously, we got about 320 kg of rice from 10 Katha. In 2020, we got 600 kg. The yield has almost doubled,” says Maity.
As soil salinity in these parts increases, non-governmental organisations like Paribesh Unnayan Parishad are helping out farmers by distributing new salt-tolerant rice varieties to help farmers and sharing relevant farming techniques.
In July 2014, there was an unusual water surge from the sea in Sagar island. The water flooded agricultural lands and destroyed crops. At that time, Amales Misra, secretary, Paribesh Unnayan Parishad and a native of Sagar, got a grant from UNDP. “Initially, the grant was for livelihood development with an emphasis on Agroforestry. But when I saw how the farmers of Sagar were struggling with a low yield of paddy, with permission, we decided to work with salinity resistant paddy,” he says.
Misra started interacting with farmers in the Sagar and Pathar Pratima blocks of Sunderban to source traditional salt-resistant varieties of paddy and to popularise them over the high yield varieties. He involved about 200 farmers of the Sagar block in the Sundarbans region of South 24 Parganas in cultivating salinity-resistant paddy.
Moreover, a seed bank has been started by the farmers with help from PUP. The farmers are provided with the seeds when the demand and price of the seeds are very high. They have to return 1.5 to 2 times the quantity of seeds given after harvesting when the price of seeds is low.
The Science Of It
“Usually, plants absorb water from the soil,” says soil scientist Sudipta Tripathi. “But in saline soil, the reverse happens. The water from the cells and the tissues of the plants move out. This process is called exosmosis.” Even the groundwater in Sagar Island is saline at shallow depths.
“The soil salinity peaks during summer. The saline groundwater rises through capillaries and increases the soil salinity. During monsoon, the rainwater washes away the saline salts in the soil,” he adds. Still, some lands are so saline that rainwater fails to make a dent in the soil salinity.
“Soil salinity has to be mapped in winter and summer land wise before crops are planted,” says Tripathi. “The farmers have to know the salinity of their agricultural lands throughout the year. So, they can plan their cultivation accordingly,” he says.
Sudipto Bhattacharjee, professor, Department of Environmental Science, Rabindra Bharati University, has been analysing the soil and water of Sagar. “We have observed that the groundwater and soil of Sagar are becoming increasingly saline,” he says.
According to him, there is a permissible salinity limit in agriculture. “1.8 ppt is very good. Some varieties of paddy can resist up to 3ppt,” he says. “Along with Sagar, the whole Sundarbans region has to move towards the cultivation of salt-tolerant paddy varieties due to climate change conditions.”
The Mondol’s get good yield during the winter. However, this year, there was no rain during the winter. As a result, the paddy is just hollow husks, says Ajit Mondol. The farmers need freshwater supply to produce a good yield even with the salt-resistant variety of paddy. They do not have permission to install submersibles to draw groundwater. In any case, the salinity has also contaminated the groundwater.
Weaning Farmers From Chemical Fertilizers
Along with salinity-resistant paddy varieties, the farmers are also using organic manure called Sagar Sona. It is made with organic refuse easily available to the farmers like cow dung, cow urine, vegetable, fish, refuse and molasses. “It is an attempt to wean the farmers away from chemical fertilisers,” says Misra.
With the increased availability of chemical fertilisers since the late 1970s and the rise of labour costs since the 1980s, the use of organic fertiliser has dramatically declined. To prevent food shortage and maximise crop yield, large amounts of chemical fertilisers have been applied to arable fields over the past few decades.
However, excessive use of chemical fertilisers has led to several issues such as serious soil degradation, nitrogen leaching, soil compaction, reduction in soil organic matter and loss of soil carbon. The efficacy of chemical fertilisers on crop yield has been decreasing over time.
Healthy soil absorbs water and carbon dioxide. But soil destroyed by chemical fertilisers releases water and carbon dioxide. This dries out the soil and turns it into dust. This process is known as desertification.
“Any organic manure can counter the soil salinity,” says Tripathi. “When we add organic manure to the soil, it slowly increases the amount of organic carbon in the soil. It serves as food for the soil microbes hence increasing their number.”
Salts in chemical fertilisers in saline soil also interfere with the nutrient intake by the plant, thereby hampering its growth. Experiments with Sagar Sona and chemical fertilisers have shown that organic fertiliser is as effective as its chemical counterparts. Besides, the product is natural, eco-friendly, pollutant-free and cost-effective.
Despite the progress made with salinity-resistant paddy variety and Sagar Sona, challenges remain. Misra rues that due to the lack of workforce and infrastructure, they have not been able to convince more farmers to switch to traditional paddy varieties.
“Market forces also have a huge impact. It is difficult to wean the farmers away from something they have been used to for so long and especially when you have paddy seed and fertiliser sellers hard-selling their products,” he says.
During peak summer, the soil salinity is maximum as the saline groundwater rises and contaminates the soil. Then even Sagar Sona fails to make a difference. “The land you are planning to cultivate in summer has to be raised from the surrounding land by digging ponds on all sides. Then the shallow saline groundwater cannot rise to the level,” says Tripathi.