Comparison of runoff quantity and quality under annual cropping and forages

Abstract

Conversion from annual cropping to perennial forages may be a beneficial management practice (BMP) to reduce runoff quantity and improve surface water quality. Runoff variables were determined in two 30 ha producer's fields over 4 years (2004–2007) using a rainfall simulator. Field 1 was cropped to barley (Hordeum vulgare L.) in 2004 and then an alfalfa (Medicago sp.) and grass mix used for hay and fall grazing was grown from 2005 to 2007. Field 2 was cropped to barley-winter triticale (WT) (Triticosecale Rimpavi Wittm.) in 2005 and alfalfa-grass for hay was grown in 2006 and 2007. Runoff variables measured were runoff depth, electrical conductivity, and concentrations and loads of total suspended solids, total N, total P, and dissolved reactive P fractions. Conversion from barley to alfalfa-grass for hay and fall grazing in Field 1 resulted in reductions for only 13% of the 10 runoff variables, 33% of runoff variables were unaffected, and 53% of variables were significantly increased. Conversion from barley-WT to alfalfa-grass used for hay in Field 2 significantly reduced 25% of the 10 variables, 40% were unaffected, and 35% were significantly increased. Converting from annual cropping to forage did not improve the majority of runoff variables.