Cullars Rotation - Experiment

Experiment

The Cullars Rotation consists of three sets of 14 soil treatments, with one set of treatments for each of the three crops (cotton, corn, and wheat and soybeans) in the rotation. Each treatment fills a roughly 2000 square foot (184 m²) plot, with a two foot (60 cm) buffer between plots. The 14 soil treatments are:

1. Legumes planted, but no nitrogen fertilizer
2. No legumes or nitrogen fertilizer
3. Nothing added to soil
4. Nitrogen fertilizer added, but no winter legumes
5. No phosphorus added
6. No micronutrients added
7. Excess potassium added
8. Rock phosphate added
9. No potassium added
10. Two-thirds of regular amount of potassium added
11. No lime added
12. No sulfur added
13. Complete fertilization with micronutrients
14. One-third of regular amount of potassium added

Continuous farming of the plots which have not been given treatments have made certain sections of the Cullars Rotation some of the most nutrient poor soil in the United States.