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The extrusion process is very popular in industry. Nowadays, extrusion is also closely associated with the 3D printing process, but this article is focused on extrusion, as a process that is mainly associated with spheronization. The extrusion product is shaped in such a way that it is suitable for the ongoing spheronization process. With this two-step extrusion-spheronization (E–S) process, it is possible to create pellets with controlled high sphericity, which are desired in tablet and capsule production due to their easily characterized (and controlled) dosage profile and good flow properties. During extrusion, it is important to monitor several parameters. This post is dedicated to one of them and that is the length of the die and its effect on the extrusion pressure as well as the effect on the extrudate surface quality.

In this paper we investigate the effects of biochar alone and its reapplication and combination with N-fertilizer (1) on the soil pH, and (2) sorption parameters. The soil samples were taken during growing period in 2018 from plots with different biochar (first application in 2014 – A, reapplication in 2018 – B) at application rates: 0 t.ha−1 (B0 control), 10 t.ha−1 (B10) and 20 t.ha−1 (B20) and different nitrogen fertilization: N0 (no nitrogen) and N40 (40 kg.ha−1). Our results showed that the first application of biochar at the rate of 20 t.ha−1 (B20A) without N-fertilizer significantly increased the values of soil pH in H2O, soil pH in KCl, the sum of base cations (SBC) and cation exchange capacity (CEC) compared to control (B0). Similar effects were observed also after reapplication of biochar (B10B). All investigated parameters in fertilized control treatment (B0N40) were worst and the first application, as well as the reapplication of biochar with N, caused significant increase of soil pH in H2O, soil pH in KCl, SBC, CEC, BS and decrease of hydrolytic acidity.