Slow-released bio-organic–chemical fertilizer improved tomato growth: synthesis and pot evaluations

Purpose Bio-organic–chemical fertilizer (BCF) has great potential to enhance agricultural production, protect environment, and improve sustainability. However, current BCFs are used only in a limited scope mainly due to the low activity of beneficial bacteria. It is significant to develop new BCFs with high beneficial bacteria activity for sustainable agricultural production. Materials and methods In this study, a novel slow-release bio-organic–chemical fertilizer (SBCF) was prepared from activated lignite, bacillus AMCC100153 (B153) (beneficial bacteria for tomato), and slow-release fertilizer (CSF) with suitable pH and low dissolubility salt content (to protect the bacterial activity). The pH and EC of different types of SBCFs with different compositions were determined and compared with those of BCFs derived from common chemical fertilizers (BCCF). The B153 activities were measured and compared with the optimum formula of SBCF. The bacillus colonization rules of SBCF and BCCF in tomato pot soil were explored by the Real-time qPCR. Results and discussion SBCF had higher bacillus activity than the corresponding BCCF. Pot experiments also showed that the bacillus formed colonization rapidly on tomato roots and secreted substances to promote root growth. The HPLC analysis found that the promoting substances were auxin and zeatin. Compared with no fertilizer control (CK) and the BCCF treatments, the SBCF treatment increased tomato yields by 73.08% and 29.04%, respectively. Conclusions Findings of this work suggest that SBCF with high biological activity and growth promoting effect has great potential in agriculture production system in the future.