Sulfate content influencing methane production and emission from incubated soil and rice-planted soil in Northeast Thailand

Abstract

This study was conducted using four soil treatments (0, 22.5, 45 and 90 mg kg−1) with balanced amounts of nitrogen (N), phosphorus pentoxide (P2O5) and potassium oxide (K2O) for each treatment, provided using ammonium phosphate sulfate (42% of sulfate), rock phosphate, potassium chloride and urea. These treatments were employed in incubation and jar experiments to investigate methane (CH4) production, redox potential (Eh) and pH of the soil. The same treatments were also used in potted soil planted with rice (Oryza sativa L.). In addition, urea-excluded treatments were also included in the incubation and jar experiments. The results showed that the presence of sulfate () reduced CH4 production from the incubation experiment. Treatments excluding urea produced larger amounts of CH4 than urea-amended ones. In the jar experiment, the soil Eh decreased from 486 to −412 mV with increased duration of flooding. In general, the presence of delayed the drop of Eh. The submerged soil with the highest amount of at 90 mg kg−1 had the lowest pH compared to other treatments. In a subsequent pot experiment, rice-planted soil showed that CH4 emission was suppressed through the growing period with increasing content of 45 and 90 mg kg−1. This suppressing effect of increasing application was clearly shown at the early growing period. The results suggest that sulfate has the potential to mitigate methane production and emission from paddy soil. However, the effects of high sulfate levels on rice yields need further study in the paddy field.