SOC is the carbon that remains in the soil after partial decomposition of any material produced by living organisms. The loss of SOC exacerbates climate change. Photograph used for representational purposes only
| Photo Credit: SPECIAL ARRANGEMENT

Across India, and especially in Tamil Nadu, forests are receiving renewed attention for their role in carbon sequestration, in line with the country’s nationally determined contribution target of creating an additional carbon sink of 2.5 to 3 billion tonnes of carbon dioxide equivalent, by 2030.

While the State is on the right path with a thrust on afforestation in areas outside forests through the Green Tamil Nadu Mission and the Trees Outside the Forests India programmes, experts say that one crucial aspect, the soil organic carbon (SOC), requires more attention. 

SOC is the carbon that remains in the soil after partial decomposition of any material produced by living organisms. According to the Food and Agriculture Organization of the United Nations, soils represent the largest terrestrial organic carbon reservoir and the loss of SOC exacerbates climate change.

At a capacity building programme conducted by Anna University’s Climate Studio for senior forest officers on Monday, March 11, A. Ramachandran, Emeritus Professor, Centre for Climate Change and Disaster Management (CCCDM), highlighted the need for enriching soil in forests with the use of plant growth-promoting bacteria. 

A digital repository to take stock of soil health

Conceptualised by Prof. Ramachandran, a web application unveiled on Monday shows a district-wise map and data on deciduous and thorn forests, the present share of SOC in soil, and the amount of compost required to enhance the carbon sink. For instance, as per the app, which has been proposed to be launched in the public domain soon, thorn forests in Dindigul have only 0.25% of SOC and need about 312.5 kg of compost per hectare. 

“One per cent carbon content is needed, that is, 1 gram for every 100 grams of soil minimum for good plant growth,” he said. From 560 samples taken from forests across Tamil Nadu, Mr. Ramachandran said that most appeared to have extremely low carbon content, making these forests unviable for healthy vegetation growth. 

Municipalities, and other local bodies can play a key part in providing the compost, said Kurian Joseph, Director, CCCDM. “Municipalities are composting but are finding it difficult to find users. So if both departments come together, two problems will be solved. Everyday 8,500 tons of biodegradable waste is generated and from that we would be getting 15,000 tons of compost,” he said.

Principal Chief Conservator of Forests and Director, Advanced Institute of Wildlife Conservation, A. Udhayan also stressed the importance of conserving soil organic carbon. “I feel that we are totally neglecting our forest soils. We are losing carbon from our forest soils even though vegetation may be present. We are exposing our soils to all kinds of impacts,” he pointed out, adding that soil must not be dug up and exposed as this may endanger its stored carbon. Other threats to soil organic carbon include forest fires, biodiversity loss, and intense rainfall leading to soil erosion, he explained.