Mineral phosphorus is a non-renewable resource that is constantly decreasing due to intensive fertilizer production. In total, 90% of mined phosphate ore is used for fertilizer purposes, so the demand for phosphorus is the highest in this sector. In this respect, it is advisable to strive to close the phosphorus cycle. In addition, economically viable phosphate-bearing deposits are concentrated in just a few locations worldwide. This comes down to the fact that most countries are simply dependent on imports of this raw material. This and the growing amount of waste have contributed to the search for alternative sources of phosphorus. One example of such phosphorus-containing waste that has fertilizer potential is sodium–potassium phosphate waste from polyol production. This article describes the effect of suspension fertilizers based on polyol production waste on the content of macronutrients in maize intended for green fodder. Fertilizers containing only basic nutrients (NPK) and fertilizers enriched with secondary components (S, Mg) and micronutrients (Zn, Mn, B) were evaluated. The conducted studies confirmed the effectiveness of the tested suspension fertilizers. The content of macronutrients in the dry mass of maize was at a similar level compared with the results obtained in the control, in which Fosdar was used for fertilization, which confirms the suitability of these products for agricultural use.