Yield and Nutritive Value of Summer Legumes as Influenced by Dairy Manure Compost and Competition with Crabgrass

Abstract

Warm‐season legumes have the potential to improve range and pasture value as well as provide wildlife feed and habitat but are often unable to compete with aggressive annual grasses on infertile, low‐P soils. A strip split‐plot design experiment was established on a Windthorst fine sandy loam (fine, mixed, thermic, Udic Paleustalf) under irrigation to evaluate legume herbage production and nutritive value in the 1999 and 2000 growing seasons in competition with crabgrass (Digitaria ciliaris Koetz.) and with dairy manure compost as a soil amendment. Legumes included ‘Sabine’ Illinois bundleflower [Desmanthus illinoiensis Michx. Mac Mill ex B.L. Rob & Fernald], rayado bundleflower [Desmanthus virgatus (L.) Willd.], partridge‐pea [Chamaecrista fasciculata (Michx.) Greene], and phasey bean [Macroptilium lathyroides (L.) Urban] grown in either pure stands or mixed with crabgrass. The application of 15.5 Mg dry matter (DM) dairy compost ha−1 yr−1 increased P concentration in all forage species but did not influence total herbage DM yield or other nutritive factors. Illinois bundleflower was the most productive legume followed by rayado bundleflower and partridge‐pea while phasey bean was the least productive. Although Illinois bundleflower had low crude protein concentrations (152–160 g kg−1), it and rayado bundleflower had lower acid detergent fiber (166–219 g kg−1) and acid detergent lignin concentrations (37–51 g kg−1) than the other entries. Soil amendment with compost did not affect legume development but did favor crabgrass competition. Competition with crabgrass depressed legume yields during the establishment year. This was less a factor during the second year, indicating that legume stand establishment is possible, albeit slowed, in the presence of an annual grass.