Subject
- Beets -- Diseases and pests -- Control -- Oregon4
- Beets -- Diseases and pests -- Nutritional aspects -- Oregon4
- Soil fertility -- Oregon4
- Soils -- Oregon -- Willamette River Valley4
- Drainage -- Oregon3
- Drainage -- Oregon -- Willamette River Valley3
- Liming of soils -- Oregon3
- Soil moisture -- Oregon -- Willamette River Valley3
- Waterlogging (Soils) -- Oregon -- Willamette River Valley3
- Alkali lands -- Oregon2
- Boron in plant nutrition -- Oregon2
- Celery -- Diseases and pests -- Control -- Oregon2
- Celery -- Diseases and pests -- Nutritional aspects -- Oregon2
- Irrigation -- Oregon -- Willamette River Valley2
- Irrigation pumps2
- Reclamation of land -- Oregon2
- Soils -- Trace element content2
- Agriculture -- Oregon1
- Airplanes, Wooden1
- Alfalfa -- Irrigation -- Oregon1