Nutrient Losses by Runoff and Sediment from an Agricultural Field in Semi-arid Tropical India

Runoff, sediment and nutrient losses were studied from an agricultural field during 2005–2009 under natural rainfall events in a semi-arid tropical region of India. The total runoff recorded was 182, 24, 35, 90 and 10 mm from 787, 292, 385, 331 and 137 mm of runoff producing rainfall events, respectively when corresponding annual rainfall was 1086, 685, 719, 764 and 610 mm during 2005, 2006, 2007, 2008 and 2009, respectively. Sediment concentration in runoff ranged between 1.31 to 4.96 g L⁻¹ with a mean value of 2.97 g L⁻¹. Erosion process exported significant amounts of nutrients from the field, totaling 20.6 kg C, 5.05 kg N, 0.05 kg P, and 9.94 kg K t⁻¹ ha⁻¹ yr⁻¹ of soil. Based on the five years data, on an average the runoff was 8.82 percent of annual rainfall and 17.65 percent of annual runoff producing rainfall events. The soil loss varied from 0.28 to 5.41 t⁻¹ ha⁻¹ yr⁻¹ during the five years. A prediction equation for runoff (r² = 0.71) was developed using daily rainfall data.