Impact of P release from bone char on soil properties in a field experiment

Acceptability of bone char (BC) fertilizers depends on their phosphorus (P) release and how the released P can be utilized by plants. We investigate P release of sulfur enriched bone char (BCplus, produced by pyrolysis of degreased animal bone chips at 800 °C and enriched with reduced sulfur compounds) in a multi-annual field experiment . Therefore, a field experiment with three different P-fertilizer treatments was carried out from 2017 to 2019 Northeastern Germany: BCplus (KK, 600 kg ha-1 every sixth year) and triple superphosphate (Min, 35 - 45 kg ha-1 annually) are compared with a non-P-fertilized control (P0). We performed measurements of soil total and plant available element concentrations to investigate P-fertilizer effects on P release and P uptake by the crop plants.
In 2019 and 2020, deviating from the plan, only one sampling was carried out: in 2019, the crops were cut after the interim harvest due to the prolonged drought. Thus, a final harvest was not possible. The following year, due to the effects of the Corona restrictions, an intermediate harvest was not possible.