This increase trend could be attributed to the increase of ions derived from mineralization of accumulated organicmatter. Increased FF reduced EC starting in wk 3. In both wk 3 and 4, ECs in 6 d1 and 4 d1 were lower than EC in 2d1
but were not different between them. PP also took effect in wk 3 that 24 h d1 had lower EC than 12 h d1
.