Conventional methods of N application for winter wheat often exhibit low fertilizer use efficiency. The comparative effectiveness of a new method, point-injection of N solution, was evaluated in two similar microplot field experiments established in southern Alberta. The first experiment, conducted over three site-year combinations in 1985 and 1986, compared yield response and fertilizer uptake in four spring-applied fertilizer treatments: broadcast urea-ammonium nitrate (UAN), broadcast urea, broadcast ammonium nitrate, and point-injected UAN, all applied in solution form. The second experiment, conducted at five sites in 1987, compared four spring-applied fertilizer treatments: surface-banded UAN, broadcast urea (granular), broadcast ammonium nitrate (granular), and point-injected UAN. All fertilizers were labeled with 15N to permit direct estimation of fertilizer uptake. The experiments demonstrated significant increases in fertilizer efficiency with point-injection under some conditions. In five of eight comparisons conducted over a 3-yr period, point-injection treatments exhibited significantly higher fertilizer use efficiency than conventional broadcast methods of application. Average fertilizer-N recovery by the crop at all eight sites was 37% in the point-injection treatments compared with only 26% in the broadcast ammonium nitrate treatment, the next most effective method of N application. When one site was excluded, because of possible confounding effects of application time, average recoveries were 34 and 26%, respectively. The increased efficiency of point-injected fertilizers was attributed to the direct placement of fertilizer N into the active rooting zone of the crop. The advantage of point-injection over conventional methods of application was highly variable, ranging from approximately 0 to over 100%, in part because of variations in precipitation patterns. The results of these microplot studies suggest that point-injection has potential for significant enhancement of fertilizer use efficiency in winter wheat, particularly in semi-arid production regions. Key words: 15N, nitrogen, urea, ammonium nitrate, fertilizer placement
Nitrogen Fertilizer Use Efficiency in Steer Gain on Old World Bluestem
