Abstract
Sewage sludge ash (SSA) is considered to be a valuable secondary raw material for the production of phosphorous fertilisers. This method of recycling may also be a solution to the problem posed by the growing amount of this waste. An innovative suspension fertiliser (SSAB) was produced from SSA and the phosphorus-solubilising bacteria Bacillus megaterium and was tested in a field experiment in the presence of spring wheat as the test plant in comparison to conventional fertilisers (superphosphate, phosphorite). Two variants of plant protection were also adopted: full chemical plant protection (+PP) and no plant protection (−PP). Besides affecting yield, it was expected that SSAB would not worsen the state of the soil environment. This paper presents SSAB effect on soil moisture and temperature, soil pH, content of toxic elements (As, Cd, Cr, Ni and Pb) in the soil, abundance of heterotrophic bacteria and fungi and the occurrence of earthworms. SSAB did not affect the tested soil characteristics when applied in reasonable doses. Plant protection had an individual effect on soil properties but did not modify the fertiliser action. SSAB may be a potential substitute for P fertilisers produced from non-renewable raw materials in times of shortage. Further long-term research is recommended to confirm these findings.
Highlights
The issues of P scarcity, its squandering and environmental pollution with P compounds call for a sustainable, circular economy of this element, which is based on the prudent use of mined resources, limited P accumulation in agricultural soils and enhanced P use efficiency and recycling [5]
This paper focuses on the assessment of SSAB effect on selected soil environment properties with a test plant, i.e., soil moisture and temperature, soil pH, content of toxic elements (As, Cd, Cr, Ni and Pb) in the soil, abundance of heterotrophic bacteria and fungi and occurrence of earthworms (Lumbricidae)
The research was based on the following assumptions: (i) soil moisture, temperature and pH, as well as the abundance and availability of P, have a direct bearing on the level of microbial activity in the soil [30] and on the activity of B. megaterium introduced with SSAB, (ii) the form of P
Summary
The application of phosphorus (P) fertilisers is accompanied by a number of negative environmental effects [1], modern agricultural production cannot do without them, and it is hard to imagine that this dependence will change if we take into account the biological importance of phosphorus [2] and the need to meet the food needs of the fast-growing world human population [3]. The research was based on the following assumptions: (i) soil moisture, temperature and pH, as well as the abundance and availability of P, have a direct bearing on the level of microbial activity in the soil [30] and on the activity of B. megaterium introduced with SSAB, (ii) the form of P fertiliser added to the soil can affect soil acidity, principally through the release or gain of H+ ions by the phosphate molecule depending on soil pH [31] and because, under P stress conditions, the plants can change the pH of the substrate through the release of organic acids which dissolve the poorly soluble phosphates [32], (iii) the potential presence of heavy metals and other toxic elements in SSAB may increase their accumulation in soil [33], (iv) the introduction of B. megaterium, as an ingredient of SSAB, to the soil environment could modify soil biology due to an increase in the strain population size followed by the reorganisation of the microbial community structure [34] and the modification of the chemical parameters of the soil environment (acid production) [30], (v) the intensity of microbiological processes [35] and the possible stimulation of crop growth resulting from the application of SSAB could indirectly lead to changes in soil moisture and temperature, (vi) changes in habitat parameters could affect the abundance of earthworms which are soil health bioindicators [36]. It was hypothesised that SSAB would not deteriorate the properties of the soil environment, i.e., that its impact would be similar or more favourable than that of traditional P-fertilisers and that plant protection would not modify SSAB effect on the analysed parameters
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
