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- Pears--Varieties 43
- Oregon Agricultural College. Experiment Station 41
- Agriculture 36
- Plants, Cultivated--Field experiments 34
- Croplands 30
- Sulfur fertilizers 28
- Agricultural machinery 21
- Orchards 13
- Oregon Agricultural College 10
- Livestock 9
- Vegetables 9
- Experiments 7
- Corn 6
- Potassium fertilizers 6
- Wheat 6
- Cows 5
- Flowering trees 5
- Nitrogen fertilizers 5
- Pasture plants 5
- Tillage--Research 5