Effect of struvite (Crystal Green) application on microbial activity and soybean yield – a preliminary study

In comparison to mineral commercial phosphorus fertilizers, struvite is considered to be a promising P fertilizer, which – in the face of dwindling phosphate resources – may replace phosphate fertilisers in the future. The fertilising value of struvite arises from its significant phosphorus content as well as magnesium and nitrogen content, enhanced by the slow release of the components. The purpose of this study was to explore the response of the soybean cultivar Abaca to struvite fertilization in terms of the plant’s yield and chlorophyll content as well as changes in the soil’s microbiological life. A pot experiment was set up at the Pawłowice Research and Education Station, on soil low in phosphorus, and with two variable factors: different application methods of phosphorus fertilizer (band and broadcast), and two phosphorus fertilisers (superphosphate and struvite). The method of phosphorus application had a significant effect on the plant’s biometric traits, chlorophyll a content and the microbial activity of soil. Struvite fertilization caused significant changes in the chlorophyll and carotenoid content. Significantly higher content of chlorophyll a and carotenoids as well as a higher total chlorophyll content were noted under struvite fertilization. Fertilizer application techniques caused a significant effect on the chlorophyll a content. Both the application methods and the type of phosphorus fertilizer had a significant effect on microbiological activity at the two measurement dates. Total glomalins content was significantly higher only in the case of band application of phosphate fertilizers at the end of the experiment, and the dehydrogenase activity was significantly increased at the flowering time of soybean following the use of this fertilizer application method. Despite the lack of significant differences in the studied elements of yield structure, their values in many cases were comparable and even slightly higher; hence, a fertilizer that aligns with the assumptions of the circular economy is worth attention and further studies under field conditions. However, long-term studies are needed to test the cultivation of plants under field conditions and their reaction to struvite as well as the effect on the content of phosphatases, which stimulate the conversion of organic phosphorus compounds into inorganic phosphates, directly available to plants and soil organisms