NITROGEN EFFECTS ON TRITICALE GRAIN-YIELD, AMINO-ACID-COMPOSITION, AND FEED NUTRITIONAL QUALITY FOR SWINE

Nitrogen fertilizer recommendations for triticale (X Triticosecale Wit tmack) and soft red winter (SRW) wheat (Triticum aestivum L.) in the s outheastern USA are similar in spite of different end uses. Grain yiel d, protein, and amino acid composition of four triticale cultivars wer e evaluated over five N levels ranging from 30 to 150 Ib/acre in four Georgia environments. Nitrogen was topdressed as ammonium nitrate at p eak tillering. Relative economic value of triticale for feed was calcu lated assuming total replacement of corn (Zea mays L.) plus variable a mounts of soybean [Glycine mar (L.) Merr.] meal (SBM) in a standard sw ine diet formulated to 100% of National Research Council (NRC) lysine requirement at representative prices for corn and SBM. Significant gra in yield responses to N occurred in three of the four environments. Gr ain yield was maximized with 90 or 120 Ib N/acre depending on environm ent and cultivar. Yield component responses to N were increased tiller density, decreased seeds per head, and decreased seed weight. Quantit y of all amino acids increased linearly with N indicating potential fo r enhancing nutritional value by increasing N to raise contents of lim iting essential amino acids. The superior lysine content of triticale relative to corn resulted in a relative cash price for triticale, whic h averaged 6% higher than corn value (range 3% to 10%). Despite N-indu ced increases in lysine content and relative nutrional value of tritic ale for feed, marginal return per acre was maximized at N levels assoc iated with maximum grain yield. Cultivars varied for all traits except tiller density. Maximum economic return per acre was obtained with im proved cultivars Florico and Florida 201, which had higher yield poten tial and test weight, but lower lysine content, than cultivars Beagle 82 and Morrison. Based on our study using 1997 prices, current N recom mendations for small grains of 60 to 120 Ib N/acre depending on previo us crop, are appropriate for triticale. At these N levels, cultivar se lection is more important for increasing returns than additional input s of N.