Is it true that soil organisms can improve soil tilth, preserve soil nutrients, and reduce a growers ...

Is it true that soil organisms can improve soil tilth, preserve soil nutrients, and reduce a growers
  work?

Is nitrogen fixation the process by which certain microorganisms absorb ammonium and convert it to
  nitrogen that plants can use?

Does the burrowing of worms, ants, and larger soil mammals mix soil layers and slow the aging of a
  mature soil?

a. inoculation
  b. improving soil conditions
  c. controlling harmful organisms
  d. tillage practices

a. Better root absorption of water and some minerals and elements
  b. Resistance to nematodes
  c. Glomalin production that enhances aggregating
  d. Longer rootlet life