Soil hydrological properties as influenced by long-term nitrogen application and landscape positions under switchgrass seeded to a marginal cropland

Switchgrass (Panicum virgatum L.) has the potential to recover the soil hydrological properties of marginal lands. Nitrogen (N) and landscape position are the key factors in impacting these soil properties under switchgrass. The specific objective of this study was to investigate the responses of N rate (low, 0 kg N/ha and high, 112 kg N/ha) and landscape positions (shoulder and footslope) on near-surface soil hydrological properties that included: infiltration rate (q(s)), saturated hydraulic conductivity (K-sat), bulk density (rho(b)), penetration resistance (SPR), water retention (SWR), pore-size distribution (PSD), and carbon (C) and nitrogen (N) fractions under switchgrass production. Data showed that, in general, the N and landscape position significantly influenced soil hydrological properties. Higher N rate decreased rho(b) (1.23 and 1.36 g/cm(3) at 0-5 and 5-15 cm, respectively) and SPR (1.06 and 1.53 MPa at 0-5 and 5-15 cm, respectively) at both depths and increased the q(s,) K-sat and Green-Ampt estimated sorptivity (S) and hydraulic conductivity (K-s) parameters, and SWR (0-5 cm depth) at 0 and -0.4 kPa matric potentials (psi(m)). Furthermore, footslope position significantly decreased rho(b), SPR at 0-5 and 5-15 cm depths, and increased the q(s,) K-sat, S, K-s, and SWR (0-5 cm depth) at every psi(m) ranged from 0 to -30.0 kPa. The higher N rate increased the coarse mesopores (60-1,000 mu m) and total pores, whereas, footslope position increased the coarse mesopores, micropores (<60 mu m), and total pores. Data from this study showed that planting switchgrass with 112 kg N/ha under footslope position helped in improving the soil hydrological properties, those can be beneficial in enhancing the biomass yield under marginal lands.