J.C. Laughlin
This paper deals with the yield and quality effects of nitrogen (N), phosphorus (P) and potassium (K) fertilisers with emphasis on the method and timing of N application. In a spring sown field experiment factorial combinations of zero, 50, 100 and 200 kg/ha of both N and P were banded at drilling. The N fertiliser had no effect on either yield or quality but P increased bulb yield by 27% and also increased storage rots. In an autumn sown experiment, N as ammonium nitrate was top dressed at zero, 50, 100, 200 and 400 kg N/ha in mid July, mid September or mid November and compared with 50 kg N/ha banded at drilling. Similar bulb yield increases of 26% were given by top dressing 50 kg N/ha at all times of application with no further increases at higher rates. Banded N had no effect on yield and there were no detrimental effects of top dressed N on quality. A second autumn drilled experiment investigated the yield response of onions to soil K levels ranging from 180 to 260 ppm and the influence of top dressed ammonium nitrate at 50 kg N/ha on the response. There was no response to soil K without top dressed N but in the presence of top dressed N, bulb yield increased by up to 50% at 240 ppm soil K. There were no quality effects from any K treatment.
Laughlin, J.C. (1989). NUTRITIONAL EFFECTS ON ONION (ALLIUM CEPA L) YIELD AND QUALITY. Acta Hortic. 247, 211-216
DOI: 10.17660/ActaHortic.1989.247.39

Acta Horticulturae