Effect of runoff and soil loss on soil hydraulic parameters and forage yield of four grass species under arid vertisols

Field experiments with grass species Cenchrus ciliaris, Dichanthium annulatum, Cymbopogon martini and Vetiveria zizanioides and control (no grass) were conducted during 1995 to 2004 in an arid vertisol at Bellary, Karnataka, India to identify a suitable grass that would reduce runoff and soil loss, and improve soil hydraulic parameters and Forage Yield (FY). Observations were recorded on runoff, soil loss and FY every year; while infiltration rate, hydraulic conductivity, Bulk Density (BD) and organic carbon were recorded at the start (1995) and end year (2004). D. annulatum gave significantly lower runoff and soil loss, while C. martini gave significantly higher FY. C. ciliaris, C. martini and D. annulatum gave significantly higher infiltration, hydraulic conductivity and organic carbon compared to V. zizanioides and control. The infiltration rate was positively correlated with both organic carbon and FY. The BD in grass plots was significantly lower compared to control in 0–15 cm, while it did not differ in 15–30 cm soil depth. C. martini attained significantly higher mean FY of 9996 kg ha⁻¹ compared to D. annulatum (6152 kg ha⁻¹), C. ciliaris (5649 kg ha⁻¹) and V. zizanioides (3525 kg ha⁻¹). An increase in runoff increased the FY, while an increase in soil loss decreased the FY in all the 4 grasses. C. martini was found to have maximum Sustainability Yield Index (SYI) of 0.338, followed by D. annulatum with SYI of 0.160 and C. ciliaris with SYI of 0.149, while V. zizanioides was unsustainable over years. The long-term study indicated that C. martini and D. annulatum were superior to minimize runoff and soil loss and improve hydraulic parameters and attain higher FY in an arid vertisol.