The impact of root systems on soil macropore abundance and soil infiltration capacity

Background and aims

Soil infiltration influences the amount of precipitation entering the soil, which is particularly important in water-limited regions. Investigating the impact of root decay on soil porosity and infiltration rates is essential.

Method

Natural grassland underwent a five-year film mulching treatment to suppress plant root growth, named grassland under film mulching (GFM). Simultaneously, natural recovery grassland (NRG) and farmland (FL) were selected for conducting in-situ infiltration experiments.

Results

The diameter of roots significantly influences the formation of soil macropores (p < 0.05). In the NRG soil layer less than 20 cm deep, the effective macroporosity with ø > 3 mm is significantly higher compared to other sites (p < 0.05), which leads to enhanced infiltration capability. Upon reaching a soil depth of 20 cm, the stable infiltration rate of FL was 2.00 mm/min, showing no significant change with further increases in soil depth. The stable infiltration rate of GFM is measured at 6.95 mm/min, which is 5.7 times higher than that of NRG. The effective macroporosity of GFM (ø > 3 mm) increased by 20.6 times, with macropore connectivity reaching 20.79%, meanwhile that the effective macroporosity of NRG (ø > 3 mm) decreased by 93.67%.

Conclusion

Although live roots contribute to the formation of macropores and infiltration capacity, the long and continuous biogenic macropores formed after root decay have a more pronounced effect on enhancing soil water infiltration capacity. This research endeavors to serve as a reference material for exploring the impact of grassland vegetation restoration on macropores and groundwater circulation.