Edge-of-field monitoring to assess the effectiveness of conservation practices in the reduction of carbon losses from the foothills of the Himalayas

Agriculture intensification and land use changes in the foothills of the Himalayas have concerning inferences on the carbon pool and storage of the soils. The foothill Himalayas (Shivaliks) are prone to large-scale soil erosion by water. There have been rising concerns regarding accelerated soil carbon loss and an increase in carbon emissions to the atmosphere. There exist limited studies in the Himalayan region to quantify the loss of soil carbon under different conservation strategies, therefore, the present study was carried out to assess the impact of conservation practices. The treatments include conventional tillage (CT), minimum tillage (MT), and zero tillage (ZT) combined with mulching (m), residue retention (r) and intercropping (i) on carbon losses through soil erosion in the foothill Himalayas. The results from one year of observations revealed that the carbon concentration in runoff water is comparable to or even greater in conservation tillage practices than under conventional tillage practices. While comparing mulch and intercropping combinations, the minimum amount of C losses were in Zero tillage + intercrop. The application of residue or mulches or intercropping with pulses effectively reduced the C losses mainly because of the reduction of runoff generated during different rainfall events. The concentration of carbon losses in sediments ranged from 1.5 to 2%. C loss in sediments during the growing season ranged from 11.87 kg ha-1 to 53.40 kg ha-1. The maximum values for sediment-associated carbon loss occurred under CT (53.40 kg ha-1) while the least was in ZTm (11.87 kg ha-1). A very high carbon enrichment ratio of 3.3 to 4.4% was observed. We observed that no till reduced soil carbon losses in sediments while covering the soil helped in controlling runoff losses as well.

Automated summary

Agriculture intensification and land use changes have significant impacts on carbon pool and storage in the soils of the Himalayan foothills. Soil erosion by water is a common issue in this area, leading to concerns about accelerated soil carbon loss and increased carbon emissions. This study assessed the impact of conservation practices, including different tillage methods and mulching, on carbon losses through soil erosion. The results showed that conservation tillage practices resulted in comparable or even greater carbon concentration in runoff water compared to conventional tillage. Mulching and intercropping with pulses effectively reduced carbon losses by reducing runoff generated during rainfall events. The carbon loss in sediments ranged from 1.5% to 2%, with the highest loss occurring under conventional tillage and the lowest under zero tillage with mulching. The study also observed a high carbon enrichment ratio of 3.3% to 4.4%.