case of the sandy soil.
The organic soil additives analyzed in this study were biochar,
slurry and manure. We used commercially available biochar
(Verora GmbH, Switzerland) manufactured from woodchips by
combustion at 575 C, containing 77.4% C and 1% N (C/N = 77.4), and
produced according to the European biochar certificate (Schimmelpfennig
and Glaser, 2012). The biochar was dried at 40 C and
ground to pass a 53 mm sieve. The analyzed slurry and manure
were obtained from an organic cattle farm in Schwäbisch Hall
(Southern Germany). The manure was cut into smaller pieces in
order to allow a more homogenous application.