Effects of nitrogen form on the activity of nitrogen bacteria group and inorganic nitrogen in rhizosphere soil of winter wheat Rhizosphere Colonization and Effects of an Endophytic Fungus DZJ07 From Eucommia ulmoides on Enzyme Activities of Wheat Root Colonization of silicate bacterium strain NBT in wheat roots Effects of urea application rate on the quantity of microorganisms and activity of enzymes in wheat rhizosphere