Abstract:In order to explore the persistence of the effects of biochar application on soil moisture and infiltration performance in black soil areas, biochar applied with 75t/hm2 (BC) and without biochar (CK) were carried out for three consecutive years from 2016 to 2018. The indoor and outdoor comparative tests of biochar treatment were carried out to analyze the soil moisture content of various soil layers and the process of soil water infiltration. The results showed that biochar application could make the soil moisture content of each soil layers increase and the extreme value ratio Ka and variation coefficient Cv decrease. And the variation of soil moisture content, Ka and Cv was getting decreased with the increase of biochar application period. From 2016 to 2018, the soil moisture content of the cultivated layer was increased the most, which was increased by 14.54%, 11.48% and 7.08%, respectively. The biochar significantly increased the soil infiltration and soil infiltration rate, enhanced the soil infiltration capacity and promoted the migration of the wet peaks. The order of soil infiltration in the BC group from 2016 to 2018 was 2016, 2017 and 2018, and the initial infiltration rate f1 was increased by 70.48%, 58.98% and 48.41%. The stable infiltration rate fc was 2016 BC treatment (1.65mm/min), 2017 BC treatment (1.22mm/min), 2018 BC treatment (1.17mm/min), 2016 CK treatment (0.46mm/min),2017 CK treatment (0.43mm/min) and 2018 CK treatment (0.38mm/min). And the 2016 BC treatment humid peak was the deepest in 2016 to 2018 at 32.24mm. The indexes indicating that soil infiltration performance was the best in the year of biochar application and then weakened year by year. The soil infiltration amount had a good power function relationship with time. The wet peak migration distance and time had a good cubic function relationship, R2 was between 0963 and 0998. Comparing the fitting results of three infiltration models of Philip, Kostiakov and Horton models, Kostiakov model had the highest R2 value (0.946~0.991) and the smallest RMSE (0.516~1.941mm/min). There was no phenomenon that the fitting parameters were inconsistent with the actual situation, also. In the case of this study, the soil water infiltration process was optimal by Kostiakov model. The results provided a theoretical basis for improving the soil water infiltration process after applying biochar in the black soil region of Northeast China.
