Silage Yield and Nutritive Value of Millet–Soybean Intercrops as Influenced by Nitrogen Application

Abstract

Shortage of irrigation water in arid and semi‐arid regions has forced forage producers to look for drought‐tolerant species for silage production. To evaluate silage yield and nutritive value of pearl millet ( Pennisetum glaucum L.)–soybean [ Glycine max (L.) Merr.] intercrops as influenced by intercropping ratios and N rates, a 2‐yr field experiment was conducted using split‐plot lay out on a randomized complete block (RCB) design. Main plots consisted of 0, 37, and 74 kg N ha –1 (N 0 , N 37 , and N 74 , respectively) and intercropping ratios of millet and soybean (50%M:50%S; 60%M:40%S; and 40%M:60%S) along with monocultures were assigned to subplots. Increasing N resulted in 9.9 and 17.6% silage yield increase at N 37 and N 74 levels compared with N 0 . Nitrogen also increased organic acids and ammonia nitrogen (NH 3 –N) content. Silage pH was lower (4.23) where no fertilizer was applied compared with the fertilized plants (4.33). The highest crude protein (CP) content (170 g kg –1 dry matter [DM]) and dry mass (248 g DM kg –1 fresh weight) was at the N 74. Silage produced by the millet–soybean mixtures was well fermented indicated by low pH and high lactic acid. Also, intercropping ratios had less acid detergent fiber (ADF) and neutral detergent fiber (NDF) than monocultures. Although all of the intercropping ratios had characteristics of well‐fermented silage, a mixture of 60% millet and 40% soybean could be superior because of higher silage yield and CP.