Alterations in yield, physicochemical components and mineral composition of onion following organic manure and inorganic nitrogen application

Abstract

Onion is the one of the most important vegetable crops grown extensively throughout the world; hence, understanding the response of the crop to the form and amount of N provided is of immense importance. In a field experiment, poultry and cattle manure (at 10 t/ha) were compared with four inorganic nitrogen (N) application levels (0, 60, 90 and 120 kg N/ha), and six combinations of manure and N applications were investigated. Plant growth and total yield (kg/ha) significantly increased, when N application increased from 0 to 120 kg/ha, with or without added poultry manure. Plant height, leaf number and neck thickness were significantly reduced at 0 kg/ha N plus cattle manure. The bulb ascorbic acid concentration significantly increased with the use of poultry manure (15.94 mg/100 g) and cattle manure (15.94 mg/100 g), compared with 120 kg/ha inorganic N (11.42 mg/100 g). No significant effects were observed on total phenolics and total soluble solids of onion bulbs following the different fertiliser treatments. Cattle manure increased P and K concentrations, whilst poultry manure significantly increased Zn and Fe concentrations in onion bulbs. Onion bulb Ca and Mg concentrations were lower when cattle manure (0.19% and 0.12%) was used than when other organic or inorganic fertilisers were used. Therefore, organic manure increases the concentrations of certain minerals in onions, compared with inorganic N application, without negatively affecting bulb size.

Keywords

• allium cepa l. poultry manure
• cattle manure
• nitrogen