The P was measured using a spectrophotometer and the K was measured
using a flame photometer. Cation exchange capacity (CEC) was 12.9 cmolc kg1. The CEC was calculated following Summer and Miller (1996). Total C (20.5 g kg1) and N (1.6 g kg1) contents were analyzed by dry combustion with a graphite furnace (FlashEA 1112,Thermo Finnigan, Milan, Italy). For more details about the soil and experimental area see Aita et al. (2014).