Nitrous Oxide Emissions from Long-Term Fertilized Black Soils in Harbin,China

At soil water content of 70% water holding capacity, different long-term fertilized black soils were incubated to investigate nitrous oxide (N
₂
O) emission. Maximal N
₂
O emission was observed at the beginning of 24-h and 48-h incubation after the rewetting of dry soil. The treatment of combined normal fertilizer N, P with manure emitted the highest N
₂
O-N, was up to 737 mug kg
^-1
. Long-term application of fertilizer nitrogen combined with manure could efficiently increase N
₂
O emission, and cumulative N
₂
O-N emissions of double fertilizer N plus double manure, normal fertilizer N plus manure and normal fertilizer N were 268, 162 and 148 mug kg
^-1
, respectively. Increasing application amount of manure could increase N
₂
O emission, and cumulative N
₂
O-N emissions of double manure and normal manure treatments were 131 and 116 mug kg
^-1
, respectively. Cumulative N
₂
O-N emission of double fertilizer N was 232 mug kg
^-1
, N
₂
O emission increased with the increase of nitrogen application. However, N
₂
O emission decreased with the increase of phosphorus application, and cumulative N
₂
O-N emissions of double fertilizer P and normal fertilizer P were 132 and 201 mug kg
^-1
, respectively. Combined normal fertilizer NPK with manure emitted lower N
₂
O, and this treated soil could supply the necessary elements of crop and soil biota and balance soil fertility.