Data from an acidity manipulation field experiment for three treatment types: control, acid and alkaline. Each treatment type had four replications at two experimental site locations and two soil types (making 48 sampling points per sampling time). The data includes chemistry data (pH, EC, DOC, SUVA254) for a variety of sample types (pore water from peat and organic soil (monthly), decomposing surface litter extracts (quarterly), and soil extracts (quarterly). Litter bag data includes mass loss of litter following a period of incubation in soil (3, 6 9 or 12 months), and chemistry of litter extracts (pH, EC, DOC, total nitrogen, SUVA254). There are up to four sub-replications per treatment replication. Data is also presented for the Tea Bag Index, including kTBI (decomposition rate) and S (stabilisation factor). There are up to three sub-replications per treatment replication.