Effects of untreated pig manure and slurry on the accumulation of soil (NH_4)~+-N and (NO_3)~--N in large-scale pig farm

摘要

The amount of soil inorganic N declined significantly with increasing of sampling depth and sampling time (P < 0.001). Compared with CK, application of untreated pig manure and slurry increased significantly the amount of soil inorganic N by 76.0% and 156.1%, respectively (P < 0.001). Compared with CK, application of untreated pig manure increased significantly the amount of soil (NH_4)~+-N by 33.7%, however, application of untreated pig slurry decreased remarkably that of soil (NH_4)~+-N by 7.4% (P < 0.001). Application of untreated pig manure and pig slurry increased significantly the amount of soil (NO_3)~--N by 86.9% and 198.0%, respectively compared with CK, (P < 0.001). Soil (NO_3)~--N accounted for the majority of soil inorganic N irrespective of fertilization treatment or sampling time, its percent were 80.13%, 84.27% and 92.63% in the CK, pig manure and pig slurry treatments, respectively. This result indicated that application of untreated pig manure and slurry increased significantly the amount of soil inorganic N, especially soil (NO_3)~--N, which occurred the potential risk of nitrate pollution.