Effects of Napier grass management on soil hydrologic functions in a karst landscape, southwestern China

• Soil saturated hydraulic conductivity in Napier grass land is relatively higher and more stable than that in cropland.
• The effects of farming practices of Napier grass on soil hydraulic properties are much higher in the topsoil than in the subsoil.
• Nitrogen fertilization has a more significant influence on soil hydraulic properties than cutting frequency and cutting intensity.

Soil hydrologic functions are important for ecological restoration in karst landscapes where soil and water loss are serious. For examining how different strategies of Napier grass cultivation affect soil hydrologic function, and to identify reasonable strategies for maintaining soil hydrologic function, this study investigated the effects of 3 years’ (since 2011) Napier grass (Pennisetum hydridum) management on soil hydraulic properties (soil field-saturated hydraulic conductivity (Kfs), water retention parameter (α)) using an orthogonal experiment (form L12(42 × 31)) in 2014. The management experiments included three levels for each of the following: nitrogen fertilization, cutting frequency and cutting intensity. Results showed that the farming practices (nitrogen fertilization, cutting frequency and cutting intensity) of Napier grass had higher influence on the soil hydraulic properties of the topsoil than those of the subsoil; nitrogen fertilization influenced the soil hydraulic properties more significantly than cutting frequency and cutting intensity. The Kfs of the topsoil generally decreased with increasing nitrogen fertilization and cutting frequency. This study suggests that the implementation of different farming practices differently alters soil hydrologic functions. Hence, in karst landscapes where water resources are limited for agricultural production, the selection of optimal farming practices for high productivity should also take soil hydrologic functions into consideration.