The Hunga Tonga–Hunga Ha'apai volcanic eruption eruption that led to the tsunami on 15th January 2022 affected the agricultural lands of Tongatapu. The extent of impacts associated with the deposition of volcanic ash and build-up of salts in soils (seawater ingression) were unknown. The work documented in this report by CSIRO was conducted to:(1) undertake a preliminary assessment of the soils in Tongatapu following these natural events, (2) determine the likely impacts on the soils’ ability to grow crops, and (3) identify possible measures that may be undertaken to remediate affected soils.