In 2011-2013, research was conducted on the fertilizer value of ash from municipal waste combustion used as an alternative source of phosphorus. A field experiment was set up on light soil. The design included 5 fertilization variants of maize, which was cultivated for grain and fertilized with mineral fertilizers and ash (P1, P2, P3): NK, NPK, NK+P1 (P1−21.80 kg P·ha-1), NK+P2 (P2−43.60 kg P·ha-1), NK+P3 (P3−65.40 kg P·ha-1). Nitrogen (80 kg N·ha-1) was applied in the form of ammonium sulphate and ammonium nitrate, phosphorus (21.80 kg P·ha-1) as enriched superphosphate and potassium (91.30 kg K·ha-1) as potassium salt. Ash, which was a substitute for phosphorus fertilizer, was obtained from the Pomorzany Sewage Treatment Plant in Szczecin in 2011-2013. It included 9.61%, and in 2013 – 7.11% of total P dissolvable in strong mineral acids. Maize harvest was done in the phase of full ripeness, afterwards the mass of grain and straw was determined as well as the total content of N, P, K, Ca, Mg and S in both yield components. The years with favourable weather conditions fostered high maize grain yield (average 10.75 Mg d.m.·ha-1) and maize straw (average 10.06 Mg d.m.·ha-1). Ash from sewage sludge combustion did not cause any significant differences in the crop volume in the particular years of research, in comparison with crop from NK and NPK treatments. The weighted average total content of macroelements in maize grain and straw from particular fertilization treatments did not vary widely, and only the highest dose of ash (P3) increased the average content of phosphorus in maize grain and straw as well as calcium in maize grain when compared to NPK. Regardless of the fertilization variant, and in relation to the feed value, an optimal N:S and ionic ratio was found in maize grain, while the ionic proportions between K:Mg and K:(Ca+Mg) were close to optimal ones. Independently of a fertilization variant, the balance of elements was negative for nitrogen and phosphorus and positive for sulphur.

20.2.2015