Lower stem nitrate concentration is used as a guide for fertilization of small grains in Arizona. The objective of this study is to determine if the timing of stem sampling has an appreciable effect on stem nitrate and corresponding fertilizer recommendations. Durum and barley were grown at the Maricopa Agricultural Center and lower stems were analyzed for nitrate from 3-leaf to maturity. Stem nitrate concentration varied considerably between the 3-leaf and 2 node stages, but thereafter was relatively constant and low (averaged 765 ppm). Stem nitrate increased after rain or N application on a few occasions, but not consistently. In this study, the timing of the stem sampling could have affected fertilizer recommendations before the 2-node stage, but after the 2-node stage, fluctuations in stem nitrate would have resulted in relatively minor differences in fertilizer recommendations.

Lower stem nitrate concentration is used as a guide for fertilization of small grains in Arizona. The objective of this study is to determine if the timing of stem sampling has an appreciable effect on stem nitrate and corresponding fertilizer recommendations. Durum and barley were grown at the Maricopa Agricultural Center and lower stems were analyzed for nitrate from 3-leaf to maturity. Stem nitrate concentration varied considerably between the 3-leaf and preboot stages, but thereafter was relatively constant and low (averaged 736 ppm). In this study, the timing of the stem sampling could have affected fertilizer recommendations before the pre-boot stage, but afterwards fluctuations in stem nitrate would have resulted in relatively minor differences in fertilizer recommendations.

Lower stem nitrate concentration is used as a guide for fertilization of small grains in Arizona. The objective of this study is to determine if the timing of stem sampling has an appreciable effect on stem nitrate and corresponding fertilizer recommendations. Durum and barley were grown at the Maricopa Agricultural Center and lower stems were analyzed for nitrate from 3-leaf to maturity. The lower stem nitrate concentration initially climbed from 3000 ppm at 3-leaf to 10,000 ppm around the 2-node stage. It then gradually declined from the 2-node stage until maturity when it fell to less than 3000 ppm In this study, the timing of the stem sampling would not have affected fertilizer recommendations, although considerable fluctuation in stem nitrate concentration was measured.