Nitrate contamination in groundwater across 502 districts in 26 states, UTs : Govt tells Lok Sabha
The Central Ground Water Board (CGWB) has detected nitrate levels above the permissible limit in groundwater across parts of 502 districts in 26 states and Union Territories, the government informed Parliament on Friday.
Citing CGWB's 2025 Annual Ground Water Quality Report, Minister of State for Chemicals and Fertilisers Anupriya Patel told the Lok Sabha in a written reply that 20.71 per cent of the groundwater samples analysed showed nitrate concentrations exceeding the permissible limit of 45 mg per litre.
"Nitrate contamination above the permissible limit has been observed in parts of 502 districts across 26 states/UTs," the minister said.
She was responding to a question from Congress MP Prabha Mallikarjun, who represents Davanagere in Karnataka.
On the situation in Davanagere constituency, Patel said that of 19 groundwater samples tested in the district, seven (36.8 per cent) exceeded the permissible nitrate limit and two (10.53 per cent) exceeded the permissible fluoride limit, while none breached the electrical conductivity threshold.
Karnataka has 27 partially-affected districts, including Davanagere, due to nitrate contamination, the reply stated.
The government, however, admitted that the CGWB has not carried out any specific studies on pesticide residues, the environmental impact of excessive fertiliser use, health effects of agrochemical use, or soil degradation linked to agricultural chemicals.
The Karnataka government similarly said it had not conducted any exclusive study on nitrate contamination or the environmental fallout of excessive fertiliser use in the state.
According to the Indian Council of Agricultural Research (ICAR), long-term studies have shown that imbalanced nutrient application — particularly the standalone use of nitrogen — leads to a decline in both crop yield and soil health.
"Excess nitrogen is primarily lost through nitrate leaching, resulting in groundwater nitrate contamination, with nitrate concentrations exceeding the permissible limit of 10 mg/L in some areas," the minister said, adding that groundwater nitrate levels were found to rise in tandem with fertiliser application rates, with higher contamination recorded in areas of intensive fertiliser use.
The minister noted that excessive and imbalanced use of nitrogenous fertilisers, especially urea, causes soil acidity or alkalinity, deficiencies in secondary and micronutrients such as zinc and boron, and leaching of nitrates into shallow aquifers.
The minister said ICAR and the Directorate of Plant Protection, Quarantine & Storage, under the Monitoring of Pesticide Residues at National Level (MPRNL) scheme, regularly test samples of food commodities and surface water, and that pesticide residue levels exceeding Maximum Residue Limits (MRL) remain under control.
Under the MPRNL project and the State Sector Programme, samples of fruits, vegetables, grains, fish and marine products, herbs and water are tested for pesticide residues; farmers in areas where residues exceed MRL or where off-label pesticide use is detected are sensitised about the risks of excessive and unauthorised chemical application.
The minister said ICAR, through its National Bureau of Soil Survey and Land Use Planning, has carried out a high-resolution (1:10,000 scale) Land Resource Inventory (LRI) in several Karnataka districts, including Davanagere.
The LRI maps soil types, land capability, erosion and drainage patterns, and feeds into soil restoration, watershed development, crop diversification and site-specific nutrient management efforts.
Karnataka's agriculture department said that during 2026-27, it is distributing organic inputs — including green manure seeds, bio-fertilisers, micronutrients and soil amendments — to farmers at subsidised rates through Raitha Samparka Kendras under various state and central sector schemes.
To check topsoil run-off and aid groundwater recharge, the state is also promoting soil and water conservation structures such as check dams, trench-cum-bunds, nala bunds and contour bunding under the Pradhan Mantri Krishi Sinchayee Yojana (PMKSY) and the Rashtriya Krishi Vikas Yojana (RKVY).
The Centre, the minister said, is pushing for sustainable and balanced fertiliser use through judicious application of synthetic fertilisers, promotion of alternate and organic/natural farming inputs, and resource conservation technologies, adding that achieving balanced fertilisation "requires a multi-pronged strategy that integrates policy, technology, and farmer participation."
