- Winter wheat -- Fertilizers -- Oregon7
- Fertilizers -- Oregon4
- Nitrogen fertilizers -- Oregon4
- Winter wheat -- Fertilizers -- Oregon, Western4
- Winter wheat -- Varieties -- Oregon, Eastern4
- Soft wheat -- Fertilizers -- Oregon, Western3
- Wheat -- Fertilizers -- Oregon, Eastern3
- Winter wheat -- Varieties -- Washington (State), Eastern3
- Herbicides2
- Peppermint -- Fertilizers -- Oregon, Eastern2
- Soft wheat -- Soils -- Oregon, Western2
- Soils -- Nitrogen content -- Oregon, Western -- Measurement2
- Weed control -- Oregon, Eastern2
- Wheat -- Economic aspects -- Oregon, Eastern2
- Wheat -- Oregon, Eastern2
- Winter wheat -- Fertilizers -- Oregon, Eastern2
- Winter wheat -- Soils -- Oregon, Western2
- Alfalfa -- Fertilizers -- Oregon, Eastern1
- Arid regions agriculture -- Oregon1
- Arid regions agriculture -- Oregon, Eastern1