A study was performed to investigate the positive impacts of humic substances (HS) on the growth of green barley, a type of green manure plant. The study was conducted in a pot culture using two different types of reclaimed soils that had been treated by land farming (DDC) and thermal desorption (YJ) methods, respectively. The experimental conditions consisted of three treatments: plant only (P), plant plus 2% HS, and no plant (control). After 89 days of culture in a controlled growth chamber, the growth of spring barley and activity of seven soil enzymes were measured. The results indicated that the addition of HS had a substantial (p<0.10) positive effect on shoot biomass in both types of soil. Furthermore, the addition of HS notably (p<0.05) enhanced all seven soil enzyme activities in both soils. Both the aboveground and belowground parts of barley plants were returned to soil and aged for 10 weeks in the same growth chamber, which resulted in notable enhancement in soil health indicators. These improvements included an increase in organic matter, a drop in bulk density, and an increase in the activity of seven different soil enzymes. When lentil seeds were planted in the aged soils, the development of the seedlings was more vigorous than that in the control in both soils, although allelopathy of barley suppressed lentil germination in soil with pH 7.0 but not in soil with pH 8.5.

Keywords: Allelopathy, Humic substance, Reclaimed soil, Soil enzyme, Green barley, Specific root length