Monitoring of soil nutrient levels by an EC sensor during spring onion (Allium fistulosum) cultivation under different fertilizer treatment

Abstract

Balanced nutrients are essential for healthy plant growth, but there is no sensor available to monitor essential nutrients such as N and K. Electrical conductivity (EC) is one of the key parameters that could be adopted to monitor these nutrient contents because soil EC is influenced by available nutrients. Therefore, the main objective of this study was to examine the effects of different basal fertilizers including inorganic, organic, and compost fertilizers, and the application ratio of basal and additional fertilizers on nutrient contents by EC sensor. The applied basal and additional fertilizer ratios were N 30:70, K 40:60, and N 20:80, K 20:80, respectively, for each fertilizer treatment. EC sensor value was positively associated with water content. Soil EC response increased with the application of inorganic fertilizer and fertigation and was positively correlated with soluble nutrients and exchangeable ammonium. The principal component analysis also determined that inorganic fertilizer was positively associated with sensor EC, soluble Na, Ca, Mg, and nitrate among the variables. This work suggested that soil available nutrients especially N can be monitored by an EC sensor which can be used to control soil nutrient status for better plant growth.