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Impact of addition of different rates of rice-residue biochar on C and N dynamics in texturally diverse soils

Singh, Gurwinder, Mavi, Manpreet S.
Archiv für Acker- und Pflanzenbau und Bodenkunde 2018 v.64 no.10 pp. 1419-1431
ammonium nitrogen, biochar, carbon, carbon dioxide, clay, crop residues, loamy sand soils, microbial biomass, mineralization, nitrate nitrogen, sandy clay loam soils, soil amendments, soil respiration, texture
Impacts of crop residue biochar on soil C and N dynamics have been found to be subtly inconsistent in diverse soils. In the present study, three soils differing in texture (loamy sand, sandy clay loam and clay) were amended with different rates (0%, 0.5%, 1%, 2% and 4%) of rice-residue biochar and incubated at 25°C for 60 days. Soil respiration was measured throughout the incubation period whereas, microbial biomass C (MBC), dissolved organic C (DOC), NH₄⁺-N and NO₃–N were analysed after 2, 7, 14, 28 and 60 days of incubation. Carbon mineralization differed significantly between the soils with loamy sand evolving the greatest CO₂ followed by sandy clay loam and clay. Likewise, irrespective of the sampling period, MBC, DOC, NH₄⁺-N and NO₃–N increased significantly with increasing rate of biochar addition, with consistently higher values in loamy sand than the other two soils. Furthermore, regardless of the biochar rates, NO₃–-N concentration increased significantly with increasing period of incubation, but in contrast, NH₄⁺-N temporarily increased and thereafter, decreased until day 60 in all soils. It is concluded that C and N mineralization in the biochar amended soils varied with the texture and native organic C status of the soils.