Impact of Broussonetia papyrifera Biochar on the Biological Attributes of Cajanus cajan and Soil Enzymatic Activities

Biochar production utilising invasive species as feedstock is recommended due to its numerous benefits, hence assessing its impact on the growth of plants and soil properties is critical.

This study investigated the impact of biochar made from the leaf litter of Broussonetia papyrifera (L.) L’Hér. ex Vent. on the growth and biochemical attributes of a leguminous crop (Cajanus cajan (L.) Huth) and soil enzymatic activities. The study was conducted in laboratory and experimental dome conditions, with biochar amendment rates ranging from 0 to 4%.

The majority of the plant-related parameters were enhanced up to a 2% amendment rate, whereas an inhibitory effect was observed at 4%, except for carotenoids, total phenolic content, and the activities of enzymes (polyphenol oxidases and peroxidases). Growth attributes (10‒80%), protein content (8‒56%), carbohydrate content (3‒30%), total phenolic content (11‒111%), and related enzymatic activities (4‒201%) were increased significantly (P < 0.05) in both roots and shoots of C. cajan seedlings with an increasing amendment rate. The effects of biochar were more pronounced on the roots compared with the shoots. At higher doses, activities of proteases, ureases, dehydrogenases, and phosphatases in soil were increased by 8–155%, indicating improved microbial functioning. The Principal Component Analysis also revealed that majority of the soil and crop growth parameters were ordinated towards a 2% biochar amendment rate.

The findings of the study provide insight into biochar-assisted biochemical alterations in the leguminous crop C. cajan via modulation of soil microbial activity, paving the way for future research into sustainable agricultural practices.