TY - JOUR
T1 - Low-dose acidification of cattle slurry with sulfuric acid enhances oilseed-rape yield but risks elevated sulfide formation during prolonged storage
AU - Zireeni, Yusra
AU - Jones, Davey L.
AU - Chadwick, David R.
AU - Mäenpää, Maarit I.
AU - Sørensen, Peter
N1 - Publisher Copyright:
© 2025
PY - 2025/3/20
Y1 - 2025/3/20
N2 - Slurry acidification using sulfuric acid (H2SO4) is an effective strategy for reducing ammonia and methane emissions during storage while providing a valuable source of sulfur (S) for crops. However, the optimal H2SO4 dose for balancing emission mitigation, S availability, and cost-effectiveness remains unclear, particularly concerning the formation of undesirable sulfides during storage. This study investigated the effects of H2SO4 dose on S transformations during storage of cattle slurry (CS), anaerobically digested slurry (DS), the liquid fraction of separated digested slurry (LFDS), and the subsequent S fertilizer replacement value (SFRV) for oilseed rape (OSR). A 5-month storage experiment at 10 °C was conducted, followed by a pot experiment. Each slurry type received three H2SO4 doses targeting pH values of 6.5, 5.5, and 4.5. Slurry pH, redox potential, dissolved sulfate, and sulfide were monitored during storage. S offtake in OSR biomass was measured at harvest, and the SFRV was assessed. Low-dose acidification of CS to pH 6.5 triggered rapid sulfate reduction to sulfide within 4 weeks of storage, while in the DS and LFDS treatments, sulfide formation was delayed at the low acid dose. The highest dose of acidification to pH ≤ 4.5 maintained lower pH and sulfide levels in all stored slurry types. The SFRV of non-acidified slurry ranged from 19 to 24 % of total slurry S, increasing with acidification and higher sulfate+sulfide content. These results suggest that low-dose acidification with H2SO4 can satisfy crop S demands but may lead to undesired sulfide formation during storage, although this effect is delayed in digested slurries.
AB - Slurry acidification using sulfuric acid (H2SO4) is an effective strategy for reducing ammonia and methane emissions during storage while providing a valuable source of sulfur (S) for crops. However, the optimal H2SO4 dose for balancing emission mitigation, S availability, and cost-effectiveness remains unclear, particularly concerning the formation of undesirable sulfides during storage. This study investigated the effects of H2SO4 dose on S transformations during storage of cattle slurry (CS), anaerobically digested slurry (DS), the liquid fraction of separated digested slurry (LFDS), and the subsequent S fertilizer replacement value (SFRV) for oilseed rape (OSR). A 5-month storage experiment at 10 °C was conducted, followed by a pot experiment. Each slurry type received three H2SO4 doses targeting pH values of 6.5, 5.5, and 4.5. Slurry pH, redox potential, dissolved sulfate, and sulfide were monitored during storage. S offtake in OSR biomass was measured at harvest, and the SFRV was assessed. Low-dose acidification of CS to pH 6.5 triggered rapid sulfate reduction to sulfide within 4 weeks of storage, while in the DS and LFDS treatments, sulfide formation was delayed at the low acid dose. The highest dose of acidification to pH ≤ 4.5 maintained lower pH and sulfide levels in all stored slurry types. The SFRV of non-acidified slurry ranged from 19 to 24 % of total slurry S, increasing with acidification and higher sulfate+sulfide content. These results suggest that low-dose acidification with H2SO4 can satisfy crop S demands but may lead to undesired sulfide formation during storage, although this effect is delayed in digested slurries.
KW - Fertilizer value
KW - Manure management
KW - Mitigation strategy
KW - Oilseed rape
KW - Redox potential
KW - Sulfide
UR - http://www.scopus.com/inward/record.url?scp=85219544913&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2025.179014
DO - 10.1016/j.scitotenv.2025.179014
M3 - Journal article
C2 - 40043648
AN - SCOPUS:85219544913
SN - 0048-9697
VL - 970
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 179014
ER -