Alkaline ameliorants increase nitrous oxide emission from acidified black soil in Northeastern China.

Lime and plant ash are common management used to achieve optimum pH for plant growth and improve soil properties in agricultural soils. Laboratory incubation was conducted to assess N20 emissions as influenced by different soil amendments (lime and plant ash) in a slightly acidic arable soil (pH 5.34). The experimental treatments consisted of CK, lime and plant ash fertilized with NH4(+)-N or N03(-)-N as nitrogen resource. The results show that lime and plant ash dramatically increases the soil pH and N20 emission. For N03(-)-N fertilization, the cumulative N20 emissions from CK, lime and ash are 421, 1669 and 921 μg N20-N/kg, respectively. For NH4(+)-N fertilization, the cumulative N20 emissions from CK, lime and ash are 361, 576 and 559 μg N20-N/kg, respectively. N03(-)-N addition leads to more N20 emission than that of NH4(+)-N addition, and lime increases more N20 emission than that of plant ash. After incubation, N03(-)-N content decreased largely. The findings suggested that alkaline ameliorants increase N20 emissions due to enhancement of soil denitrification.