Effect of Chromolena Odorata and Citrus Sinensis Extract Treated Rice Husk and Maize Cob on Sandy Soil and Maize

ABTRACT This study investigated the effects of Chromolaena odorata (Akintola) and Citrus sinensis (orange) leaf extracts applied to rice husk and maize cob on the physical and chemical properties of sandy soil and the growth performance of maize (Zea mays L.). A total of 60 plots were used in a Randomized Complete Block Design, and treatments were applied at 0%, 5%, 10%, 15%, and 20% concentrations. The results showed that the combination of Chromolaena odorata extract with maize cob at 20% significantly improved soil bulk density (1.88 g/cm³), indicating enhanced soil structure and reduced compaction.In contrast, the combination of Orange Leaf + Maize Cob at 5% showed the least improvement in bulk density (1.057 g/cm³), indicating a relatively weak effect on soil structure. Similarly, porosity was most enhanced by Chromolaena odorata + Maize Cob at 20% (53.8%), while the lowest improvement was recorded under Orange Leaf + Rice Husk at 5% (34.0%). For hydraulic conductivity, the highest value was observed in Orange Leaf + Rice Husk at 10% (1.521 cm/sec), whereas the lowest was found in Chromolaena odorata + Maize Cob at 15% (0.842 cm/sec). On chemical properties, the highest nitrogen content was recorded in Chromolaena odorata + Rice Husk at 15% (5.29%), while the same treatment at 20% dropped to a lower value (0.42%), suggesting potential inconsistencies at higher concentrations. Organic carbon content peaked under the same treatment at 15% (2.83%). These results demonstrate that both the type of extract and the amendment level significantly influenced the outcomes. The study concludes that Chromolaena odorata and orange leaf extracts, particularly when combined with maize cob or rice husk at 15–20%, can significantly improve soil fertility and maize growth. However, lower concentrations, especially with orange leaf extract, had limited effects on key soil parameters. The study recommends further research into the optimal combinations and application levels of organic residues and leaf extracts to support sustainable agricultural practices.