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The Old Rotation circa 1896 |
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The Old Rotation circa 1896 |
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Photo Gallery Click on any picture below to see a larger version. |
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| The Old Rotation (circa 1896) was placed on the National Register of Historical Places in 1988. Today, it is the oldest, continuous cotton experiment in the world and the third oldest, continuous field crop experiment in the United States. | ||
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The Old Rotation was started by Professor J. F. Duggar to demonstrate the benefits of winter legumes as a cover crop and crop rotation on cotton and corn production in the South. | |
| The Old Rotation consists of 13 nonirrigated plots on one acre of land. |
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| Fall-seeded legume (crimson clover) residue provides the nitrogen for cotton and corn, which are planted in April (corn) through early May (cotton). Since 1996, corn and cotton have been planted directly in the clover residue using conservation tillage. This photo shows crimson clover (foreground) and rye (far background) in early April. |
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Cotton is planted every year in Plot 1 (foreground behind sign) with no winter legumes and no N fertilization. Cotton is also planted in Plot 2 (the next adjacent plot) and demonstrates the benefits of a winter legume with no additional N fertilization.(This is a view of the Old Rotation as seen looking south in late June.) | |
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Cotton is ready for harvest. Cotton in Plot 1 (left) was grown with no winter legumes and no N fertilizer; cotton in Plot 2 (right) was grown with winter legumes but without N fertilizer. | |
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Plot 6 is a replicate of Plot 1 (cotton grown with no winter legumes and no N fertilizer). It produces an average of 400 pounds of lint per acre per year. The N removed in the lint and the seed is about what is received in rainfall during the growing season. Soil organic matter is around 0.5% in this plot. | |
| A three-year rotation of cotton (winter legume), corn (small grain harvested for grain), soybean results in more than 2.5% soil organic matter and the highest average cotton lint yields (two bales per acre). Only 60 pounds N is applied during the three-year rotation and that is applied to the small grain, which is either wheat or rye. |
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| A two-year rotation of cotton (winter legumes) and corn with or without N fertilization produces about the same cotton (two bales per acre) and corn yields (120 bushels per acre) as the three-year rotation. |
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Planting cotton every year with 120 pounds N per acre as fertilizer and no winter cover crop has resulted in poor soil quality (less than 1% soil organic matter) and severe soil crusting in the spring. In spite of the difficulty of getting a stand of cotton with conventional tillage, long-term average yields have been only slightly less than the two-year or three-year rotation. This is typical of most cropping situations in the South. | |
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Soybean yield has averaged 35 bushels per acre on the three-year rotation when double-cropped after wheat or rye harvest. | |
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