Degradation of 14C-zinc ammonium acetate in soils as influenced by soil types, soil sterilization, and carriers

Zinc ammonium acetate (ZAA), typically applied to soils in anhydrous ammonia as a carrier, has been used to improve corn (Zea maysL.) productivity. This study aimed to determine the fate of ZAA in soils as influenced by soil type (sandy, silt, and clay loam), sterilization (sterile and non-sterile), and two carriers (H2O and NH4OH). A 16 d laboratory incubation experiment with 14C-ZAA showed that total recovery of carbon-14 (14C) from 14CO2 trap and soil extraction by CaCl2 ranged from 72% to 94% in the first 8 d for sterilized soils. However, < 17% 14C was found in non-sterilized soils. Most 14C recovered in sterilized soil was associated with soil extraction, and relatively little was found in the CO2 traps. All sterilized soils provided similar 14C recoveries except the sandy loam. Slightly more 14C was extracted from the soil when NH4OH was the ZAA carrier rather than water. Conversely, recovery of 14CO2 continued to increase during the 16 d incubation, but started faster when water was the ZAA carrier. Microbial activity appeared to be instrumental in the assimilation and disappearance of ZAA.