Picture Courtesy: Shera Doelkar, Sr.Forestry Officer
Planting trees along with crops, constructing dry stone walls and growing hedgerows in the fields are found to be effective interventions towards soil conservation according to a study. These interventions can reduce soil erosion, retain soil fertility and carbon stock resulting in improved agricultural productivity.
A senior forestry officer with the Thimphu Thromde, Shera Doelkar, carried out a study to find out the amount of carbon and nitrogen in the soil loss due to erosion.
Bhutan is a mountainous country and its steep terrains and slopes make it more prone to soil erosion resulting in the loss of soil fertility and soil nutrients.
Using a scientific method called the RUSLE model, the study compared the amount of soil nutrients lost before and after the initiation of soil conservation efforts.
“The study showed that there was a significant impact of terracing on soil organic matter loss with 65.5 per cent of prevented specific soil organic matter loss from the study site. By comparing the different conservation practices, it was found that dry stone wall terracing is the most effective in hilly areas as it reduces slope length,” Shera Doelkar said.
“Through the agroforestry schemes that is by planting fruit trees and fodder with the crops, it was found that carbon storage in the watershed can be improved by 134.9 tons in 50 years.”
She said these interventions are found to improve agricultural productivity.
“So one per cent increase in the soil organic carbon increases like two to more than five per cent of available water content depending upon the soil texture and the organic carbon content. Therefore, by reducing the soil organic carbon loss or soil organic matter loss, we can increase the available water capacity hence increasing the soil fertility and improving the agricultural productivity,” she added.
The study recommends agroforestry practice as it has multiple benefits. It is found that the practice can contribute in ensuring food security and improving the livelihood of farmers while at the same time prepare the country towards adapting and mitigating climate change and climate change induced hazards such as land degradation.
The study also recommends the construction of dry stone wall terraces. It says the cost incurred in the construction of dry stone wall terraces can be recovered by increased agricultural productivity.
The study was carried out in Dagana in 2016 given the district’s remoteness and poor agricultural productivity.
