PS 28-131
Soil infiltration under different grass types in Southwestern China
Infiltration is the process of water entry into the soil from land surface. The soil-water infiltration process plays an important role in water budget, soil erosion and nutrient cycle in a watershed as it determines the relationship between surface water and soil water. Plant community controls the infiltration of soil by affecting soil structure and properties. This study was intended to examine how different types of grasses influenced soil infiltration processes. We hypothesized that grass species that differ in rooting features led to different soil infiltration responses under the same soil type. To test this hypothesis, the characteristics of infiltration processes were investigated in four grass types and a bare land in the Three Gorges Reservoir Region in Chongqing, China. The four grass types were (1) Vetiver (Vetiveria zizanioides Lin. Nash), (2) Bahiagrass (Paspalum notatum Flugge), (3) Bermuda (Cynodon dactylon L. Pers.) and (4) Alfalfa (Medicago sativa L.). Soil infiltration measurements were determined using double ring infiltrometer approach. The structural features of roots were measured in the grass sites. The relationships between infiltration rates and root traits were developed and evaluated.
Results/Conclusions
The results showed that grasses significantly increased soil infiltration rates when compare to the bare land (P < 0.05). On average, the mean infiltration rate and steady state infiltration rate were in the order of Vetiver (3.37 and 3.00 mm/min) > Alfalfa (2.42 and 2.11 mm/min) > Bahia (1.79 and 1.39 mm/min) > Bermuda (1.65 and 1.38 mm/min) > bare land (0.86 and 0.71 mm/min) in the study site. The differences of the soil infiltration rates between the studied sites were mainly attributed to the variation of root structural traits in the grasses. Root length density (cm/cm3) and root surface area density (cm2/cm3) were significant higher in Vetiver (9.20 and 5.15) and Alfalfa (9.20 and 4.47) than in Bahia (3.25 and 1.54) and Bermuda (1.85 and 0.99). Regression analysis indicated that the mean infiltration rate, steady state infiltration rate and 90-min cumulative infiltration amount were positively related to root length density and root surface area density. Particularly, the relationship between infiltration rates and root traits mainly occurred in the diameter class of root size of 0.5-5 mm. Our results confirm the vulnerability of soil infiltration to land cover modification, while also highlighting the influence of the different grass type covers present in the study area.