Nitrogen mineralization and CO2 and N2O emissions in a sandy soil amended with original or acidified pig slurries or with the relative fractions

The following six pig slurries obtained after acidification and/or solid/liquid separation were used in the research: original (S) and acidified (AS) pig slurry, nonacidified (LF) and acidified (ALF) pig slurry liquid fraction, and nonacidified (SF) and acidified (ASF) pig slurry solid fraction. Laboratory incubations were performed to assess the effect of the application of these slurries on N mineralization and CO2 and N2O emissions from a sandy soil. Acidification maintained higher NH4 (+)-N contents in soil particularly in the ALF-treated soil where NH4 (+)-N contents were two times higher than in LF-treated soil during the 55-171-day interval. At the end of the incubation (171 days), 32.9 and 24.2 mg N kg(-1) dry soil were mineralized in the ASF- and SF-treated soils, respectively, but no mineralization occurred in LF- and S-treated soils, although acidification decreased N immobilization in ALF- (-25.3 mg N kg(-1) soil) and AS- (-12.7 mg N kg(-1) soil) compared to LF- (-34.4 mg N kg(-1) soil) and S-treated (-18.6 mg N kg(-1) soil) soils, respectively. Most of the dissolved CO2 was lost during the acidification process. More than 90% of the applied C in the LF-treated soil was lost during the incubation, indicating a high availability of the added organic compounds. Nitrous oxide emissions occurred only after day 12 and at a lower rate in soils treated with acidified than nonacidified slurries. However, during the first 61 days of incubation, 1,157 mu g N kg(-1) soil was lost as N2O in the AS-treated soil and only 937 in the S-treated soil.