Mississippi Centennial Rotation - Yield, Nutrient Uptake and Removal, and Cropping System Value.

Long-term crop rotations have been studied for many years around the world dating as far back as the 1840’s in England.  Long-term crop rotations involving cotton date back to 1896 with the “Old Rotation” at Auburn University, the first experiment to demonstrate that a cotton/legume crop rotation could be used to support a cotton crop indefinitely.  In 2004, a long-term cropping systems research study was established involving cotton, corn, and soybean at the Delta Research and Extension Center located near Stoneville, MS.  The systems were set up to utilize the most up-to-date technology available including bio-technology in cultivars, high fertility management, improved cultural practices, and irrigation in replicated field trials.  The six systems have included 1) continuous cotton, 2) cotton/corn [2-yr system], 3) corn/cotton/cotton [3-yr system], 4) corn/soybean [2-yr system],  5) soybean/corn/cotton [3-yr system, and 6) soybean/corn/cotton/cotton [4-yr system].  It should take 12 years for all system to return to the same point and the cycle will repeat.  After six years, the 2-yr systems have completed three cycles and the 3-yr systems have completed two cycles.   Since the original plan was to evaluate cotton, only cotton has been grown continuously.  Soybean and corn have not been grown in mono-crop cultures and both crops have been shown to respond positively to rotation.  Soybean has been grown in a twin-row configuration on 102-cm beds while corn and cotton continue in a single-row configuration.  Nutrient uptake and removal calculations are estimated based on crop yields with soil samples taken following each crop year and fertilizer applications made to optimize production.  Cotton yields have been lower in the continuous cropping system as expected and result in the lowest nutrient removal.   The value of the cropping system has been estimated using average annual prices or the loan price whichever is higher.