Effects of lignin on nitrification in soil.

The effects of two lignins isolated from black liquor from pulping process on nitrification in soils after addition of urea, (NH4)2SO4 and (NH4)2HPO4 were investigated by incubation at 20 or 30 degrees C for 7 or 14 d. The effects of lignin on nitrous oxide emissions from soil were also determined. Results showed that both lignins were more effective for inhibiting nitrification of NH4(+)-N as (NH4)2SO4 or (NH4)2HPO4 as compared to urea-N. The effectiveness of lignin on nitrification was markedly affected by different soil type and temperature. Nitrous oxide emissions from soil declined when lignin was used. Urea plus 20 and 50 g/kg lignin reduced N2O emissions by about 83% and 96%. respectively, while (NH4)2HPO4 plus 20 and 50 g/kg lignin respectively reduced emissions by 83% and 93%. Because of its low cost and nonhazardous characteristics, lignin has potential value as a fertilizer amendment to improve N fertilizer efficiency.