I understand Rhizobium does not necessarily overwinter well and that there
are soil predators which feed on it. We are in a mild climate (soils
generally do not freeze although we do get a dusting of snow) and summer
day tempertures average in the 70's.
Is there a general rule of thumb, i.e., if the crop nodulated last year, no
need to inoculate this year. Or, if you have had the crop within the last
3 years and it nodulated, no need to inoculate this year. Or, inoculate
every year regardless of crop/nodule history. Or, to complicate things,
perhaps certain plant species need inoculum every year while others don't.
I look forward to some learned opinions.
Carol A. Miles, Ph.D.
Washington State University
Extension Agricultural Systems
360 NW North Street
Chehalis, WA 98532
PHONE 360-740-1295 FAX 360-740-2792