This study was conducted to investigate the enhancing ability of cover crops to P availability of alternative phosphorus fertilizers under differing soil conditions by quantifying their effects on maize growth and P uptake traits. Three cover crops (CC) including buckwheat (Fagopyrum esculentum), red clover (Trifolium pratense) and phacelia (Phacelia tanacetifolia) and three phosphate fertilizers (PF) including rock phosphate, ash from sewage sludge and digestate were utilized in a greenhouse pot experiment with maize as the main crop. Growth and P uptake of maize were least under Buckwheat treatment while no significant differences were found between the control, Red clover and Phacelia. This can be attributed to the lower shoot P concentration as well as wider C/P ratio of Buckwheat residues, which favours P immobilization rather than mineralization. Slight impact of soil and PF were observed on shoot P concentration and C/P ratio of maize. While no significant interaction between the main factors during maize growing period was drawn in this study. No clear enhancing effect of CC on P from PF was detected, hence further research is recommended.