Effect of lignin from paper-making black liquor on the transformation and the bio-utilization of urea-N

Urea coated with lignin from paper-making black liquor were made in different layer thickness. Nitrogen release rate of lignin coated with urea (LCU) in soil were determined by leaching experiment. Pot experiment was conducted to study the fertilizer efficiency of LCU, which was used as a slow-release nitrogen fertilizer, on corn. Results showed that urea coated with lignin presented slow-release property to different degree. Nitrogen release rate of LCU was about 12% lower than that of normal urea, utilization ratio of nitrogen was about 7.8% higher than that of mormal urea. the result indicated that LCU could increase the yield of the corn and utilization ratio of nitrogen compared with un-coated urea. In addition to its slow-release effect, the degradation product of lignin was an effective nitrification inhibitor, which could reduce the loss of nitrogen and protect environment from N pollution.