Assessing Stachytarpheta jamaicensis (L.) Vahl growth response and rhizosphere microbial community structure after application of food waste anaerobic digestate as biofertilizer with renewable soil amendments

A combination of soil amendments (biochar, organic compost, and rice husk) and anaerobic digestate of food waste may ensure high cropland productivity and resource efficiency. This study evaluated the effectiveness of food waste anaerobic digestate (FWAD) as a replacement for commercial fertilizer in growing Stachytarpheta jamaicensis (L.) Vahl (ornamental plant) under different soil amendment conditions. The results of soil coupling amendments such as biochar, organic compost, and rice husk positively affected Stachytarpheta jamaicensis growth, with the added FWAD. Adding coupling soil amendments along with the added FWAD significantly enhanced the chlorophyll content index, height, and number of leaves in Stachytarpheta jamaicensis. Under the addition of FWAD, the chlorophyll content index of soil coupling biochar amendment revealed 53.08 +/- 0.07, while soil coupling rice husk amendment revealed 53.68 as compared to the control soil growing medium with 52.58 +/- 0.07. Meanwhile, the plant height and the number of leaves increased by up to 27%, for soil coupling biochar and rice husk amendment, respectively. The microbial community analysis of the rhizospheric zone of Stachytarpheta jamaicensis revealed the top phylum in all treatments is Acidobacteriota, Actinobacteriota, Bacteroidota, Cyanobacteria, Firmicutes, Fusobbacteria, Gemmatimonoadota, Halobacterota, Latescibacterota, Myxococcocccota, Proteobacteria, Spirochaetota, Synergistota, and Verrucomicrobiota. FWAD is shown to have significant effects on the growth of Stachytarpheta jamaicensis in this study, thereby providing practical implications for replacing commercial fertilizer with FWAD.