Soil rewetting to mitigate CO2 emissions of shallot cultivation in tropical peatland

CO2 emissions are agriculture-related problems in peatlands, requiring mitigation. Irrigation and mulching are needed to reduce CO2 emissions in peatlands. This research aimed to study the effect of irrigation system and type of mulch for soil properties and CO2 emissions at shallot cultivation in peatlands. This research was carried out on degraded peatland in the Kalampangan village, Sebangau District, Palangkaraya, from April to December 2017. A split-plot design repeated at 4 times was employed. The main plot was type of rewetting, including manual watering (P) and sprinkler methods (S), the subplot was type of mulches, comprising TM = without mulch, G = weed in situ (Stenochlaena palustris) mulch, J = straw mulch (Oryza sativa). Observed variables included soil pH, Eh, EC, organic C, water contents, and CO2 emissions, performed twice within two months. The results showed that the sprinkler irrigation system and mulch did not affect significantly on pH, Eh and soil moisture content, but significantly influence EC and organic C. The sprinkler irrigation system reduced CO emissions up to 10% (2916 kg/ha/season) compared to conventional 2 methods (3250 kg/ha/season). Compared to no mulch (6175 kg/ha/season), Kalakai mulch (Stenochlaena palutris) reduced CO2 emissions up to 33% (4119 kg/ha/season) and rice straw increased CO2 emissions up to 32% (8207 kg/ha/season).