Mississippi's Centennial Rotation - the First Twelve Years: Yields, Nutrient Uptake and Nutrient Removal.

Mississippi’s Centennial Rotation was initiated on the Delta Research and Extension Center in 2004 and completed the first 12 years in 2015.  The rotation systems utilized the latest technology available for crop production and included cotton, corn, and soybean.  The rotation systems included 1) continuous cotton, 2) cotton/corn [1:1], 3) cotton/cotton/corn [2:1], 4) corn/soybean [1:1], 5) soybean/corn/cotton [1:1:1], and 6) soybean/corn/cotton/cotton [1:1:2].  Each crop is grown each year  for direct comparisons of the systems with respect to production and price.  Producers make their decision on crop mix based on prices and profit potential.  After 12 years, the 2-years rotation have completed six cycles, the 3-year rotations have completed four cycles, and the 4-year rotations have completed three cycles. In the 13^th season all systems have returned to their initial spots.  Grain prices reached all-time highs and crops have set all-time record yields in the last 12 years with a shift from cotton to grain crops.   Early planting, irrigation, and early harvest have given growers an advantage in the market place.  With comparable yields, nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) removal by grain crops could be two to three times higher than cotton.  This requires additional nutrient replacement to maintain high yields.  After 12 years, continuous cotton has removed far less nutrients compared to a corn/soybean rotation.  The more grain crops in a rotational system, the greater the N, P, K, and S removal and a potential need for replacement.  As these rotations continue the difference in nutrient removal will also continue to grow.  Unlike many of the long-term rotation studies, the Centennial Rotation is replicated and allows for statistical comparisons of systems with fewer years of data.  While profitability may change from year to year with varying prices levels and yields, the rotation benefits are still present.