Effect of Drip Irrigation and Fertilization Timing and Rate on Yield of Onion

Abstract

ABSTRACT There is insufficient information on the effects of drip irrigation and drip fertigation with nitrogen on growth and development of onions. The aim of the present work was to investigate the possibility of using these techniques in connection with fertilization, where nitrogen is split into preplant and side-dress application, that is used in onion (Allium cepa L.) production. Yield of spring sown onion (cvs. Riviera F1 and Utopia F1 in 1999 and cv. Riviera F1 only in 2000), were investigated in field experiments on a sandy-loam soil. Nitrogen fertilization consisted of a preplant application of 50 kg·ha−1 N incorporated in all treatments, and a side-dress application of: (1) 50 kg·ha−1 N in dry form without irrigation, (2) 50 kg·ha−1 N in dry form plus drip irrigation, or (3) 50, or (4) 150, or (5) 250 kg·ha−1 N in surface fertigation, applied through drip lines, and (6) 150 kg·ha−1 N in subsurface fertigation, applied through buried drip lines. In comparison with the not irrigated or fertigated control, addition of 50 kg·ha−1 N in dry form to the drip irrigated treatment 2 resulted in a significant marketable yield increase of both onion cultivars (cv. Riviera F1–18% and cv. Utopia F1–28%). Marketable yield increased as a result of application of 50 kg·ha−1 N, with fertigation (treatment 3, i.e., cv. Riviera F1–27% and cv. Utopia F1–55%). Fertigation N rates higher than 50 kg·ha−1 (treatments 4 to 6) did not increase onion yields. In 2000, the yield increase due to application of N in dry form and irrigation (treatment 2) was not significant. Higher marketable yields were produced when the 50 kg·ha−1 N rate was applied through drip fertigation (41% increase, treatment 3) and highest after applying 150 kg·ha−1 N (treatment 4) through fertigation (79% increase as compared to the control). Subsurface fertigation (treatment 6) had similar effects on yield as did surface fertigation. Irrigation and fertilization had little affect on total N concentration in onion plants.