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 mays L.) 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 ¹⁴CO ₂ 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.