Tamil Nadu’s Cauvery delta has grown rice for millennia but environmental alarm bells warn that the days might be numbered for large-scale rice cultivation. Within a few decades, intensive farming practices have changed almost everything about the region, with potentially irreversible consequences. It has ramped up water use even as the Cauvery river dispute choked off water supplies. The delta is almost sucked dry now and its soil is stripped of nutrients. Nutritious native varieties that kept the soil and the people farming it healthy have all but disappeared.
Cauvery delta, South India’s largest delta, is crucial for Tamil Nadu’s food security. This is the second part of a series of reports on rice cultivation in the region by Navya PK and it investigates the consequences of the shift to high-yield paddy.
The buzz of customers doesn’t settle even at night at Guna Traders, a large fertiliser shop in Mannargudi, in the heart of Tamil Nadu’s Cauvery delta. The samba season – the delta’s biggest paddy farming season – is on, and the shop is racked up to the roof with thousands of colourful plastic bottles carrying pesticides and fertilisers from local to multinational companies. In the next few months, Cauvery delta’s paddy farms are going to soak up these chemicals and more.
Since the Green Revolution, high-yielding paddy varieties have replaced almost everything else in the delta. But this didn’t mean big profits for farmers, or healthy food for consumers.
In Part 2 of this series on the delta’s looming water crisis, we investigate the consequences of the shift to high-yield paddy: these varieties need large amounts of chemical fertilisers and pesticides whose repeated use has depleted the delta’s soil, which, in turn, means that the rice grown here lacks certain nutrients essential for our health and growth. While farmers are attempting to compensate for the soil damage by using even more fertilisers, this only worsens the problem. The only beneficiaries of the intensive chemical farming system seems to be big fertiliser and pesticide companies who dominate the market, and not the farmers themselves.
High-yield paddy puts an end to crop diversity
In the seven delta districts we are analysing, paddy is the king. And in five of these districts, paddy is so prominent that it’s grown in two-thirds of the total cropped area.
Historically, delta farmers mostly grew only one season of paddy as well as pulses and some millets. In the colonial period, the British administration enhanced two-season paddy farming to some extent to meet their needs.
But with the Green Revolution, two- or three-season farming became the norm: the state’s paddy research stations frequently churned out high-yielding varieties ideal for paddy monocropping, MSP encouraged farmers to focus almost exclusively on the crop, and chemical fertilisers became popular with subsidies. In the process, native varieties, which need less water and no chemical fertilisers, were completely sidelined.
The rice grown here are almost entirely high-yielding varieties.
High-yield paddy traps farmers in a cycle of low incomes and high input costs
The shift to paddy monocropping didn’t mean big gains for farmers. Most farmers this reporter spoke to had only 4-8 acres of land, and earned profits of only Rs 2-3 lakh per year.
Most say their cost of growing high-yielding varieties is Rs 30,000 or more per acre.
PR Pandian, General Secretary of the Cauvery Delta Farmers’ Association, says, “If you consider all aspects like the interest farmers pay on the money borrowed, land invested for farming, and the family’s labour, the cost comes to Rs 45,000 per acre. In that sense, the farmer is not making any profit.”
Farmers usually earn only Rs 40,000-54,000 per acre from paddy sales, depending on the yield. The numbers mentioned in this section are based on farmers’ anecdotes; we have not verified them independently.
Yet farmers continue to grow paddy as the government procures it, and the MSP ensures fixed – even if low – returns every season. Growing other crops is riskier as market price fluctuations can lead to huge losses. For example, in 2021 cotton prices rose to Rs 110 per kg, prompting farmers to grow more of it, but the price crashed by about half the very next year.
Thennilavan says, “The money is not enough for us. I’m continuing paddy farming only because my family has been doing it for generations and we can’t abandon the land now.”
Farmers say that between a third and a fourth of their farming cost goes only towards buying fertilisers, pesticides and weedicides. But much of this fertiliser use is unnecessary, experts say.
Intensive farming practices for high-yielding rice is sapping the soil of nutrients
Monoculture of high-yielding paddy and the associated fertiliser use is stripping the delta’s soil of essential nutrients like nitrogen and zinc. This means that compared to the rice that farmers used to grow, today’s rice has less protein and minerals, which can lead to stunting, anemia and a host of other chronic conditions associated with poor diet
Delta districts, like other rice-growing districts of Tamil Nadu, had low nitrogen in nearly all soil samples tested under the union government’s Soil Health Card scheme in 2023-24. Across Tamil Nadu, 2.5 lakh soil samples were tested under the scheme that year.
Prof P Stalin, Assistant Professor of Agronomy at Annamalai University, Cuddalore, says, “When the same crop is grown continuously, nutrients get extracted at the same soil level, that is at 10-15 cm depth from the ground. And since paddy has a fibrous root system, it extracts nutrients only from the top layer.” Repeated farming of the same variety – such as BPT that fetches higher prices – worsens the problem.
Prof R Jagadeeswaran, soil scientist and professor at the state university Tamil Nadu Agricultural University (TNAU), says substituting manure (which provides organic carbon in the soil) with chemical fertilisers is another reason for low nitrogen levels. “Organic carbon supplies 90% of nitrogen in the soil,” he says. “Even if you apply excess urea to compensate for this, only 40% of the nitrogen will stay in the soil, as the rest is lost to leaching, denitrification, etc.”
He says manure application has declined due to the decline in cattle population, along with stoppage of the traditional practice of recycling agricultural waste after harvest.
Low soil nitrogen impacts protein synthesis in rice, which means the rice we eat will be low in protein. “The grain will have a higher-than-normal ratio of carbohydrate to proteins and minerals,” Prof Jagadeeswaran says.
Soil Health Card data also shows that Thanjavur and Thiruvarur rank among the worst five districts in Tamil Nadu in terms of soil zinc levels, with four-fifth of their soil samples being zinc-deficient. Like nitrogen, zinc also gets extracted from the soil continuously with paddy monoculture.
Prof Jagadeeswaran says, "Though the agriculture department recommends zinc sulphate application every season, farmers may not always do this.”
Low zinc levels cause stunting (low height-for-age) in children, immune deficiency, neurological and reproductive problems.
Besides, the low organic carbon in the soil in delta districts reduces the uptake of essential nutrients like phosphorus and micronutrients like iron, which makes the rice less nutritious.
A 2023 study by the Indian Council of Agricultural Research (ICAR), under the union agriculture ministry, found that the zinc levels in high-yielding rice varieties have reduced by a third, and iron levels by a quarter, over the past 50 years. Whereas the concentration of toxins like arsenic in rice has multiplied. Though the Green Revolution made India food-sufficient, it has compromised our nutritional security and made the population more disease-prone, the study said.
Farmers use excess fertilisers to compensate
Several delta farmers we spoke to are aware that their soil is depleted but said they have little choice but to apply more fertilisers to compensate, which worsens soil damage and increases pesticide use. Mindful that the food they grow is less healthy, some farmers even grow native rice varieties in a small part of their farm to ensure nutritious food for their own family.
Thanjavur farmer Thennilavan M says, “Earlier, the soil quality was better due to the use of manure, coconut shells, etc. Now the soil is so damaged that I have to use more and more fertiliser to get good yield.”
Our analysis of NPK fertiliser use data shows that four delta districts – Thanjavur, Cuddalore, Pudukkottai and Tiruchirappalli – use more nitrogen-based fertilisers than the state average. These districts, except Pudukkottai, also use more potassium-based fertilisers than average. Phosphate-based fertilisers’ use was above the average in Cuddalore and Tiruchirappalli.
At Guna Traders that sells fertilisers to about 60,000 delta farmers, proprietor Vivek Rajagopal says farmers buy 110-150 kg of urea per acre in a season. This is 2-2.5 times the TNAU’s recommended use for samba season. Urea is heavily subsidised by the government, with a 45-kg bag costing the farmer only Rs 266, prompting them to overuse it.
Overuse of subsidised fertiliser exacerbates the problem
Though farmers assume that excess urea use will improve yield, Prof Stalin says this isn’t true and is actually making the problem worse. “After urea application, the crop immediately looks greener, so farmers think the crop is responding well. But it uses up the nitrogen before its flowering stage, so there is no impact on yield.”
In fact, excess urea use causes paddy stalks to bend into the soil as well as soil and water contamination. It also attracts pests, which then increases farmers’ pesticide use. Rajagopal says he sells 10 crore litres of pesticides annually.
In Cuddalore, which uses excess N, P and K (Nitrogen, Phosphorous and Potassium) fertilisers, a fifth of the soil samples tested are acidic. Prof Stalin says, “Fertilisers are mostly acidic in nature, so their continuous application has made the soil acidic here. This reduces paddy’s uptake of nutrients, especially calcium and magnesium.”
In the long term, excess fertiliser use will reduce yield and threaten food security, soil scientists warn.
Prof Stalin says TNAU’s blanket recommendation on urea itself is too high for the delta, and that it can even be halved and supplemented with organic fertilisers based on soil tests. "Before growing paddy, you have to do soil tests to know the nutrient availability in soil, and make a fertilisation schedule based on that. But farmers consider this a tedious task.”
Though the agriculture department tests soil samples and gives fertiliser use recommendations to individual farmers under the Soil Health Card scheme, only a small proportion of farms get tested. In 2023-24, only 2.5 lakh out of nearly 80 lakh farm holdings in the state were tested under the scheme.
Across the delta, the dominant fertiliser company is the Tamil Nadu-based Southern Petrochemical Industries Corporation (SPIC). Whereas MNCs like Syngenta and Bayer, along with Indian companies like Tata, dominate the pesticide segment. Among herbicides, Bayer’s Roundup is most popular.
In 2023-24 FY, Bayer India reported a turnover of Rs 51 billion, and SPIC reported Rs 19 billion.
Devinder Sharma, food and trade policy analyst, says the government itself is supporting corporates and chemical farming through subsidies for urea, diammonium phosphate (DAP), etc. “There is no denying that there are lobbies for chemical farming. And the biggest lobbies are agricultural universities. They are the biggest stumbling block when you seek change towards healthy agriculture.”
Read Part 1 here: Tamil Nadu’s Paddy Paradox: Cauvery delta turns on the taps even as wells run dry
Read Part 3 here: Tamil Nadu’s Paddy Paradox: Uphill battle for sustainable alternative in Cauvery delta
(Reporting for this story was supported by the Environmental Data Journalism Academy - a programme of Internews’ Earth Journalism Network and Thibi)
View the data analysis conducted for this series, and the methodology used for the analysis.