Comparison of nitrogen application via a trickle irrigation system with surface banding of granular fertilizer on red raspberry.

A field trial compared applications of ammonium nitrate N as soil-surface bands of granular fertilizer with applications as a solution through a trickle irrigation system (i.e., fertigation) on yield, plant growth and end-of-season extractable soil inorganic nitrogen of red raspberries (Rubus idaeous L.). The granular application was made once in early spring, and the fertigation was scheduled as eight weekly applications from early to late spring in each of 4 successive years. Three rates of N (33, 67 and 134 kg N ha−1) were applied by both methods and a zero N control was also included. The N treatments had relatively small effects on berry yields, being significant in the last 2 years (1988 and 1989) only. Applications of granular N resulted in equal or greater yields than the control, whereas the fertigation method resulted in equal or lower yields than the control. Granular applications tended to enhance cane growth and N concentrations in the fruiting cluster, laterals and leaves of fruiting canes. ...