Effects of enriched biochar treatments on CO2 release, soil nitrate and ammonium, and wheat growth parameters in saline soils

The effects of treatment with simple and enriched biochar on microbial respiration, nitrate and ammonium concentrations, and wheat growth parameters in saline soils were investigated using a completely randomized factorial experimental design with three replications, three soil salinity levels (1.5, 4.5 and 9 dS.m-1), and five biochar treatments including control, 2% simple (SB) or enriched biochar (EB) amendment, and 4% SB or EB amendment. The basal respiration rate and the concentrations of ammonium, and nitrate were measured at multiple time points. Additionally, total soil nitrogen, organic carbon, and microbial biomass carbon, microbial biomass nitrogen, and microbial biomass phosphorus were measured together with the height and fresh and dry weight of wheat after a 100-day growth period and at the end of the experiment. Salinity significantly affected basal respiration, nitrate and ammonium concentrations, plant height, and wet and dry weight. Biochar amendment significantly affected pH, basal respiration, nitrate and ammonium concentrations, total soil nitrogen, soil organic carbon, microbial biomass carbon, microbial biomass nitrogen, and microbial biomass phosphorus in both rhizosphere and non-rhizosphere soil, as well as wheat height, and wet and dry weight. The interaction between salinity and biochar significantly affected nitrate and ammonium concentrations and also plant height and fresh and dry weight. Finally, the effects of different biochar amendments and salinity levels on the basal respiration rate and the concentrations of nitrate and ammonium varied significantly over time. Overall, the results obtained show that biochar amendment can significantly moderate the adverse effects of soil salinity, especially if enriched biochar is used.