Soil tests in Kuttanad paddy fields show aluminium levels 39 to 165 times above safe limits

Soil tests in Kuttanad, the rice bowl of Kerala, have revealed dangerously high aluminium concentrations in paddy fields, posing a serious threat to crop health and productivity.

Analyses of soil samples collected from paddy fields in different parts of Kuttanad and upper Kuttanad by the Kerala Centre for Pest Management (KCPM), and tested at the Rice Research Station, Vyttila, under the Kerala Agricultural University, showed aluminium levels ranging from 77.51 parts per million (ppm) to 334.10 ppm. This is about 39 to 165 times higher than the permissible level of two ppm or two mg per kg of soil for rice cultivation.

Smitha B., project director, KCPM, said the problem was linked to increasing soil acidity. “We collected samples from 12 paddy fields, and all of them showed very high aluminium concentrations. Aluminium becomes more soluble and toxic as soil pH drops below five, with its availability increasing tenfold for every unit decline in pH. Excessive aluminium damages the plant root system and severely interferes with the absorption of essential nutrients such as phosphorus, calcium, potassium, and magnesium. In highly acidic soils, iron, along with aluminium, is also present in quantities harmful to plants,” she said.

Officials said corrective measures must focus on reducing soil acidity. “When soil acidity decreases, and the pH rises above 5.5, the solubility of aluminium and iron declines, reducing their harmful effects. Effective control of soil acidity is possible only through the application of liming materials and proper leaching. The most effective materials for controlling excess aluminium are dolomite and calcium silicate,” said an official.

Threat to livelihood

Meanwhile, Kodikunnil Suresh, MP, said the alarmingly high aluminium contamination pointed to a “grave environmental imbalance”. From an agricultural perspective, Mr. Suresh said the decline in soil productivity and the resulting significant reduction in paddy yields directly threaten the livelihoods of thousands of small and marginal farmers.

“The government should intervene urgently to scientifically assess the extent of aluminium contamination in the Kuttanad region, identify the sources of pollution, and implement immediate soil and water remediation measures,” he said.