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Topic
- Oregon Agricultural College. Experiment Station 43
- Plants, Cultivated--Field experiments 32
- Sulfur fertilizers 27
- Oregon State Agricultural College. Agricultural Experiment Station 12
- Potassium fertilizers 6
- Universities and colleges--Faculty 6
- Nitrogen fertilizers 5
- Tillage--Research 5
- Hens 3
- Knowlton, Frank L. (Frank Lester), 1894-1940 3
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Work Type
- black-and-white photographs 60
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Decade
- 1920-1929 60