Effect of liming on soil nitrogen loss in runoff from a cultivated bamboo stand

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Liming is an effective method of mitigating soil acidification. However, the effect of lime treatment on soil nitrogen (N) loss through runoff from fields remains unclear. A bamboo stand (<i>Phyllostachys praecox</i> C.) with high N content and severe acidification was selected to investigate the effect of liming on soil N loss through runoff. A laboratory experiment was conducted to determine the liming effect on N mineralization and pH using the recommended liming rate in field. Results showed that soil pH increased from 3.1 to 5.6 and soil nitrification rate significantly improved when a liming rate of 10 Mg ha⁻¹ (3.98 tn ac⁻¹) was applied in the field. The total dissolved N (TDN) concentration in the runoff ranged from 1.98 to 41.6 mg L⁻¹ in the nonliming treatment and from 1.98 to 33.3 mg L⁻¹ in the liming treatment. The event mean concentrations (EMCs) of TDN in the plots of the liming and nonliming treatments were 5.80 and 6.72 mg L⁻¹ (<i>p</i> &lt; 0.05), respectively. Total N loss through runoff was reduced by liming from 12.4 to 10.6 kg ha⁻¹ (11.0 to 9.44 lb ac⁻¹; <i>p</i> &lt; 0.05) at a rate of 14.5%. Runoff in the field mainly occurred in summer season, and N loss in nitrate (NO₃) form accounted for approximately 70% of TDN. The high N uptake by bamboo plants and increased ammonia (NH₃) volatilization may be attributed to the decline of TDN in the liming treatment compared with those in the nonliming treatment. Results indicated that a reasonable liming rate in an acid-cultivated land can benefit crop production and nutrient loss control.