Abstract:The effects of lignin and biochar addition on soil nitrogen (N) and phosphorus (P) nutrients and water loss were researched in order to reduce the cost of soil amendment, increase the utilization of lignin that came from papermaking black liquor, and promote the application of lignin in soil amendments. The biochar amendment and lignin were selected as the comparison in this study. The effects of lignin and biochar with different additions (0, 1%, 2%, and 4% respectively in the mass fraction) on N, P, water loss, urease activity and pH value in soil were studied by the soil column simulation method and static absorption method. Both addition of lignin and biochar in soil could alleviate the changes of pH value and could inhibite the activity of urease. The inhibition effect was obvious after adding N fertilizer 1~20 days when the inhibition rate was positively correlated with the addition amount. Compared with the CK, the amount of lignin and biochar added with 1%, 2% and 4% could significantly reduce the volatilizing amount of ammonium N by 8.29%, 14.29%, 14.86% and 3.79%, 11.65%, 15.26%, respectively. Total N leaching amount was significantly reduced by 32.37%, 37.70%, 42.49% and 25.43%, 30.70%, 39.54%, respectively. Total P leaching amount was significantly reduced by 23.68%, 40.48%, 48.12% and 6.97%, 22.88%, 35.30%, respectively. The water loss was significantly reduced by 7.71%, 15.82%, 9.29% and 9.91%, 15.00%, 16.06%, respectively. In this experiment, the best mass fraction of lignin and biochar was 2% and 4% respectively when the inhibition effect on soil N, P nutrients and water loss was the best. Therefore, it could be found that lignin could replace biochar amendment in soil to some extent for the similar function of water and fertilizer conservation and similar effect on inhibiting urease activity to biochar.