Ethylene production in anaerobically incubated soils amended with poultry litter

Ethylene is a plant growth-regulating substance that is produced by plants and soil microorganisms. Ethylene production and accumulation in soils is stimulated by the addition to the soil of compounds such as methionine, which serves as a direct precursor in ethylene biosynthesis, and by flooding, which encourages anaerobiosis. The objective of this laboratory study was to determine if the addition of either non-composted or composted broiler litter stimulated ethylene production in three ana-erobically incubated agricultural soils from eastern Arkansas. A completely randomized design was used, with non-composted and composted broiler litter as the two sources applied at three rates each. Check treatments received no litter. Both non-composted and composted poultry litter significantly increased production of ethylene in soils under flooded conditions, compared with the unamended control. At the highest rate of addition of non-composted litter (9.4 g kg), ethylene production in the Hilleman, Foley, and Bosket soils was 821, 678, and 327 nmol kg soil, respectively. At the same rate of addition of composted litter, ethylene production in these same soils was 491, 440, and 254 nmol kg soil. There were significant differences among soils in the quantities of ethylene produced, with the soil having the coarsest texture and lowest organic carbon content, the Bosket, producing the least ethylene. More ethylene was produced per gram of added carbon with non-composted litter than with composted litter. Differences in the abilities of the two wastes to promote ethylene production in soils may be due to differences in the bioavailability of carbon in the two materials. The compost had a lower total organic C content and a higher humic acid content than the non-composted material. The yield response of lowland rice to applications of poultry litter may be due in part to enhanced ethylene accumulation in the waste-amended soils.