Enhancing productivity of onion plant using a mixture of organic and chemical fertilizers with charcoal powder

Abstract

This study aimed to evaluate the effect of the interaction between chemical and organic fertilizers and different charcoal levels (0%, 5%, and 10%) on the growth of onion (Allium cepa L.) and its content of essential mineral nutrients. The experiment included three treatments consisting of chemical fertilization (20–20–20 NPK and diammonium phosphate fertilizer, DAP 18–46%) combined with organic fertilization and varying charcoal application rates. Several vegetative and root growth parameters were evaluated, in addition to the plant contents of nitrogen, phosphorus, and potassium.

The results demonstrated that the third treatment (chemical fertilization + organic fertilization + 10% charcoal) significantly outperformed the other treatments in most of the studied traits. It recorded the highest mean plant height (57.76 cm) and the greatest mean leaf length (44.39 cm), along with superior root system development. Chemical analysis also revealed a significant increase in nutrient content in plants treated with 10% charcoal, with the highest values recorded for nitrogen (1.66%), phosphorus (0.31%), and potassium (2.14%).

This improvement may be attributed to the role of charcoal in enhancing the physical and chemical properties of the soil, increasing its capacity to retain nutrients, and improving their availability to plants. The findings indicate that integrating 10% charcoal with chemical and organic fertilization represents an effective strategy for improving onion growth and enhancing the uptake of essential nutrients.