Thiruvalla: Large quantities of aluminium are accumulating in paddy fields across Upper Kuttanad and Kuttanad, driven by climate-related environmental changes, posing a serious threat to rice cultivation in the region.

Analysis of soil samples collected from affected areas by the State Pest Surveillance Centre revealed aluminium concentrations ranging from 39 to 165 times above permissible limits. The lack of regular rainfall has been identified as a major factor contributing to the spike.

The presence of 2 ppm (parts per million), or more than 2 milligrams of aluminium per kilogram of soil, can adversely affect paddy yield. However, the samples showed aluminium concentrations far exceeding this threshold, with the lowest recorded at 77 ppm and the highest reaching 330 ppm.

All the affected fields were found to lack proper irrigation systems, preventing the neutralisation of acidic elements in the soil.

Farmers apply subsidised limestone powder as a corrective measure. However, in areas where aluminium levels were a hundred times higher than permissible limits, this treatment has made little difference. In addition, harmful proportions of iron, along with aluminium, were detected in paddy grown in highly acidic soil.

pH value should not drop below 5.5
Commenting on the findings, B Smitha, Project Director, State Pest Surveillance Centre, called for steps to regulate soil acidity

"When the pH value rises above 5.5, the solubility of aluminium and iron decreases. Limestone products should be used based on the soil’s acidity level. Dolomite or calcium silicate should be applied at a rate of not less than 100 kg per acre," she noted.