Abstract: In the present study， temporal and spatial variation characteristics of salt in greenhouse soils were explored under different irrigation frequencies （every 5， 10， 15 d） during pepper growth by simulated experiments of soil box in greenhouse. It was shown that the whole monitoring period could be classified into 3 phases based on the changes of soil electrical conductivity （EC）: rapid decrease phase （1-20 d after first irrigation）， slow decrease phase （21-40 d after first irrigation） and stable phase （41-62 d after first irrigation）. In rapid decrease phase and stable phase， EC value in 0-20 cm soil layer decreased as every 5 d > every 10 d > every 15 d. In slow decrease phase， EC value in 0-20 cm soil layer decreased as every 5 d > every 15 d > every 10 d. In both slow decrease phase and stable phase， the smallest salt accumulation in 0-20 cm soil layer was found under the irrigation frequency of every 10 d， indicating a stronger saltleaching effect of this irrigation frequency.

Key words: irrigation frequercy, secondary salinization, soil salinity, spatial and temporal dynamic