摘要：Application of biochar has been suggested to improve water and fertilizer-retaining capacity of agricultural soil. The objective of this study was to evaluate the effects of wheat straw-derived biochar on water retention capacity, and ammonium (NH4+) and nitrate (NO3-) leaching from the arable calcareous clay soil of Loess Plateau by soil column experiment. Results showed that the cumulative leachate volume significantly (P < 0.05) reduced from 1148 ± 11.0, 1115 ± 7.00 to 1069 ± 5.00 mL as biochar application rate increased from 1%, 5% to 10%, which reduced the leachate volume of 2.13%, 4.94% and 8.87% compared to the control treatment (no biochar application), respectively. Biochar inhibited NH4+ leaching. The cumulative masses of NH4+-N leached from 1%, 5% and 10% biochar application soil columns were 4.87 ± 0.07, 4.20 ± 0.21 and 3.59 ± 0.11 mg respectively, much lower than control (5.32 ± 0.20 mg). However, biochar promoted NO3- leaching. The cumulative masses of NO3--N leached from 1%, 5% and 10% biochar application soil columns were 81.6 ± 1.40, 78.2 ± 0.90 and 73.5 ± 2.40 mg respectively, much higher than control (71.1 ± 2.10 mg). Furthermore, both the cumulative masses of leached NH4+-N and NO3--N decreased as biochar application rate increased. This phenomenon may be the incor- porated result of stimulated nitrification and enhanced adsorption of NH4+ and NO3- caused by biochar addition. Notably, our results suggested a potential negative effect of biochar on NO3- leaching in intensively fertilized cropland soils, which should be investigated further in future.
