Fluctuation in Lower Stem Nitrate Concentration in Small Grains, 2006

Abstract

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.