This study was carried out to evaluate the correlations between soil physico-chemical properties and
onion (Allium cepa L.) plant nutrients in a long-term onion producing area over 30 years, during the
growing season of 2010–2011. Soil and plant samples were collected from 16 onion growing fields.
Each mineral content of onion plants showed different trends in conversion from the initial bulbing stage
to harvest.
Nutrient uptakes of leaf tissue decreased from the initial bulbing to harvest, while nutrient uptakes of onion bulb substantially increased.
In soil, water content, nitrate-nitrogen (NO3 N), and electric conductivity with high mobility decreased from the initial bulbing to harvest, but available phosphorus (av. P) or exchangeable cations with highly accumulated content did not change significantly.
At the initial bulbing, soil N or NO3 N and ex. K content were not positively correlated with each
counterpart in leaf tissue, while av. P content was positively related with leaf P content.
However, bulb N, P and K were not significantly correlated with each counterpart in the soil.
Soil N or NO3 N at the initial bulbing were negatively associated with bulb nutrients at harvest, especially Mg or soluble solid content.
Soil av. P content at the initial bulbing showed strongly negative correlation with dry matter (DM),
carbon (C), calcium (Ca), magnesium (Mg) and iron (Fe) at harvest.