It would also help the country access climate change funds for green growth, Deputy Minister of Agriculture and Rural Development Le Quoc Doanh said at conference in Hà Nội on December 1.
In Vietnam, greenhouse gas (GHG) emissions from rice cultivation are estimated to account for more than half of emissions by agriculture production as a whole.
Reducing GHG emissions in agriculture production in general and rice production in particular would be crucial to the nation’s climate change response, Doanh said.
It would also contribute to fulfilling national commitments to reduce GHG emissions, he added.
According to the General Statistics Office, Vietnam grows rice on 4.14 million hectares, using up 59.2 percent of agriculture production land for annual crops.
According to the Ministry of Natural Resources and Environment, in 2014, rice cultivation generated 44.6 million tonnes of CO2 emissions or 50.5 percent of the agriculture production in total. Total GHG emissions that year reached 225.6 million tonnes.
Not much interest
The deputy minister said that private firms were still not particularly interested in low carbon rice projects because of common risks involved in agricultural investments as well as a lack of supporting policies.
The rice industry reform plan approved by the agriculture ministry last year promotes public-private-partnership in agriculture projects, but many localities have failed to raise funds for their own part while calling on the private sector to invest, Doanh said.
Tran Xuan Dinh, deputy head of the agriculture ministry’s Cultivation Department, said that in rice production, greenhouse gas was mostly generated and emitted when the rice fields were covered by water.
Underground chemical reactions in processing nutrients, the photosynthesis of rice, anaerobic micro-organisms’ activities produced greenhouse gases like dinitrogen monxide N2O or Methane NH4, he said.
In Mekong Delta provinces, farmers have been applying the mid-season drainage method to reduce GHG emissions and save water.
Mid-season drainage involves the removal of surface flood water from the rice crop for about seven days towards the end of tilling. The duration of the dry period must be long enough for rice plant to experience visible moisture stress.
According to climatetechwiki.org, mid-season drainage aerates the soil, interfering with anaerobic conditions and thereby interrupting CH4 production.
Mid-season drainage of a rice crop involves withholding flood irrigation water for a period until the rice shows symptoms of stress. It involves ridge and furrow cultivation technology, where some moisture still exists in the soil even after the toe furrow is drained.
It is essential to check when the crop has used most of the available water. The degree of soil cracking will depend on the soil type and on the spatial distribution of the rice cultivars.
The cumulative evapo-transpiration of the crop varies from 77-100mm during the time water is removed, depending on crop vigour and soil types. The field is then re-flooded as quickly as possible. It is necessary to cover the soil surface with water so that the plants start recovery. Water depth then can be gradually increased to that required for protection of the developing plant canopy from damaging high temperatures during anthesis.
Mid-season drainage reduces methane emissions from paddy fields.
Tran Van The, deputy head of the Institute for Agriculture Environment, said this method is feasible and can deliver great benefits.
In Mekong Delta provinces, if the right scheme is followed, farmers can save half the water used in a rice season. More sparse sowing helps rice have better photosynthesis, fewer diseases, and therefore, require less fertliser.
Mid-season drainage could help save one third of product costs compared with conventional rice production while productivity was the same or higher, The said.
“Farming techniques and drainage systems are key to the success of the mid-season drainage method,” he said, calling on the Government and investors to prepare a proper infrastructure for drainage works.
Other experts at the conference agreed that the Government and private investors should pay more attention to integrating low carbon farming into the development of agriculture infrastructure.