Researchers have introduced improved practices that produce higher yields and do not employ hazardous burning to prepare the land.

‘Sonor’ farming is a method of rice cultivation on drained peatland practised by, among others, communities in Ogan Komering Ilir District in South Sumatra Province, Indonesia.

Sonor involves ‘slash and burn’ clearing without tillage of the soil. Farmers considered burning vegetation in their drained peat fields during the long dry season to be more effective than other methods because it reduced the cost of preparing the land for sowing and, they claimed, provided a source of nutrients for the rice crop. After burning, farmers would broadcast rice seeds, up to 100 kilogram per hectare, directly by hand. They would not apply fertilizer during the growth of the rice.

However, using fire to clear land increases the level of degradation of the peatland by destroying the peat’s composite leaf litter and other organic matter, including most of the micro-organisms that collaborate with soils and plants to provide nutrients and other services that support life. Peat degraded by fire has low total nitrogen, a decreased carbon/nitrogen ratio in drained peat and low total organic carbon value.

Whatsmore, the thick, pungent smoke from the smouldering peat is hazardous to human and animal health owing to its composition, which includes carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, carbonyl compounds, polycyclic aromatic hydrocarbons and other irritant and hazardous volatile organic compounds.

‘Overall, the sonor practice is unfriendly to human health and the environment and, further, results in low productivity of 1–2 tonnes per hectare compared to the national average of 4–5 tonnes,’ said Muhardianto Cahya, a student of the Master’s Program in Agricultural Science at Sriwijaya University and the author of a journal article on the study published in the journal, BIOVALENTIA, in May 2022.

To address these issues and seek solutions, a research team from Sriwijaya University and the Center for International Forestry Research and World Agroforestry (CIFOR-ICRAF) set out to find ways not only to obviate the use of fire but also increase productivity.

In collaboration with farmers in the village of Perigi in the subdistrict of Pangkalan Lampam, South Sumatra Province, during December 2019 to April 2020 the researchers tested improved methods of planting and growing rice with new, high-yielding varieties. At the same sites, they also have been testing incorporation of various tree species and tree species for timber, bioenergy and biomaterial, reported separately.

Using a ‘split-plot’ design, the main experimental plots used 1) direct broadcasting of 25 kilograms of rice seed per hectare; 2) direct broadcasting of 75 kilograms rice seed per hectare; 3) transplanting using the ‘jajar legowo’ 2:1 method with a spacing of 20 x 40 x 10 cm; and 4) transplanting using a spacing of 20 x 20 cm treatments, with subplots using the Inpari 30 and Inpara 3 varieties.

The land was prepared for planting without burning, instead using herbicides and removing plant residues manually. The soil was hoed and plots measuring 3 x 4 m established and distanced 1 m apart. Fertilizers were applied a week before broadcasting seed or transplanting seedlings. Seedling preparation for the jajar legowo and transplanting treatments was carried out simultaneously with the direct broadcasting treatments.

Results of the researchers’ experiments proved their original hypothesis.

‘We found that the broadcasting treatments produced the lowest numbers of tillers compared to the others,’ said Rujito Agus Suwignyo, professor with the Center of Excellence on Peatland Research at Sriwijaya University and corresponding author of the research team’s report. ‘The jajar legowo treatment had higher productivity than the other planting treatments, with 3.7 tonnes per hectare. It is interesting that the Inpara 3 rice variety showed better growth and production on degraded peatlands under the sonor method but the Inpari 30 showed higher growth and production under jajar legowo. This action research was done without applying agricultural lime, so we believe that we can get 5–6 tonnes per hectare if we add lime before planting.’

The improved planting methods increased rice yields in terms of total number of tillers (the specialized grain-bearing branches of the rice plant), number of productive tillers, number of grains per panicle (the top part of the rice plant that bears the rice grains), grain weight per panicle, grain weight per m², and plant biomass.

‘These results are very promising for contributing to the eradication of fire used to clear peatland for planting,’ said Himlal Baral, senior restoration scientist with CIFOR-ICRAF and a co-author of the journal article, ‘while at the same time improving farmers’ livelihoods and health as part of efforts to restore degraded peatland. The experiments were conducted on the same sites where the team have also been studying integration of trees for bioenergy and food along with fish for consumption and sale, a concept known as “agrosilvofishery”, that can also play a role in restoration of degraded peatland.’

*The ‘jajar legowo’ planting system alternates between two or more (usually two or four) rows of rice and one empty row. ‘Jajar’ is one of the words for ‘row’ in Indonesian. ‘Legowo’ is a portmanteau word from the Javanese ‘lego’ (broad) and ‘dowo’ (elongated).

The research work described in this story was funded by the National Institute of Forest Science of the Republic of Korea through a grant to CIFOR. The research was conducted by Sriwijaya University’s Center for Excellence on Peatland Research through a Letter of Agreement: Peatland Restoration in South Sumatra: Paludiculture Strategies using Potential Bioenergy Crops.

Read the journal article

Cahya M, Suwignyo RA, Sodikin E, Baral H. 2022. Increasing rice productivity in degraded peatlands using improved planting methods and rice varieties. BIOVALENTIA: Biological Research Journal 8(1):69–82.

Read more

MUST-HAVE BOOK: Bioenergy for landscape restoration and livelihoods through agroforestry

Peatland restoration: connecting science with policy and practice