Use of Stabilised Amine Nitrogen (SAN) Reduces Required Nitrogen Input and Increases Yield of Onions (Allium cepa L.)

Abstract

Nitrogen is the main nutrient required by plants for growth. The production of onions (Allium cepa) results in low nitrogen use efficiency (NUE) as nitrogen is applied when it is not required by the plant; resulting in loss to the environment. This work assessed the ability of stabilised amine nitrogen (SAN) to increase the NUE and yield of onion. In a glasshouse, two onion cultivars (F1 Hybound (pelleted) and Ramrod) were grown and fertilised with 150 kg N ha−1 as urea applied to the soil or 2.7 kg N ha−1 as SAN applied foliarly at the three, four and five leaf stages. The survival percentage, number of leaves, height, weight, bulb diameter and stem diameter were recorded. For both cultivars, the survival percentage was increased with the SAN, with the increase being significant for Ramrod. While for all other parameters, SAN resulted in significant increases for both cultivars. In field plot trails, applications of 150 kg N ha−1 were compared to applications of 7.56 kg N ha−1 as SAN, which gave statistically similar yields and increased the NUE. This work shows that considerably reduced N as SAN was a significant improvement over the traditional 150 kg N ha−1 for onion production. Commercial application of this work would significantly improve the profitability of onion production due to reduced purchase of N and increased yield.