AbstractCorn (Zea mays L.) is an Â¡deal crop for silage because of its high levels of fermentable carbohydrates, but its major limitation for use in human and animal feeding is its low crude protein (CP) concentration. An alternative to increase CP in corn silage is through its association with annual legumes. This study involved intercropping two annual legumes, lablab (Lablab purpureus) and sunn hemp (Crotalaria juncea), with two yellow corn cultivars (HR-ORO and QPM) to assess the effect on dry matter yield (DMY); botanical composition of forage; CP, neutral and acid detergent fiber (NDF and ADF) contents; and fermentation products upon ensiling. The experiment was conducted in the Experimental Substation at Isabela, Puerto Rico, between September and December 2009 In an Oxisol soil. The experimental design was a split plot with 2 x 3 factorial; the main plots were the corn cultivars, and the subplots were the legume-corn associations and corn monoculture, with four replicates per treatment. Compared with that in corn monoculture, the mean incidence of weeds in the crop decreased from 31.08 to 13.64% in the associations, as the DMY increased from 8,216 to 10,068 kg/ha. The dry matter (DM) content of the silages was higher (P < 0.05) in monoculture (26.05%) than in association with lablab (24.30%), whereas CP increased from 9.5% (monoculture) to 10.6% (association). The overall content of NDF in the silage was 53.56%, and that of ADF increased from 32.68% in monoculture to 37.26% with legume inclusion. The overall values of the silages were pH, 3.75; percentages of lactic, acetic and total acids, 6.96, 2.53, and 9.40; and proportion N-NK/N total, 5.55%. There was little effect of the treatments on these variables, which is indicative of well-preserved silage. Corn-legume associations benefited weed control and DMY in the field, and increased the CP content of silage without affecting the fermentation process.
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