Mississippi's Centennial Rotation - Changes in Soil Nutrient Levels over Time in Multi-Crop Rotation Systems.

Mississippi’s Centennial Rotation was established in 2004 to commemorate the 100-year anniversary of the Delta Research and Extension Center.  Production was changing and technological advances were evident in all aspects of agriculture.  After 12 years, cotton acreage has declined and grain crops, corn and soybean, have appeared along with the infrastructure to handle the crops.  Rotations were initially set up with all crops grown during each growing season and included five system compared to continuous cotton.  The 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].  All rotations systems have four replicates allowing for statistical comparison after only a few years.  After 12 years, the 2-year rotations have completed six cycle, the 3-year rotations have completed four cycles, and the 4-year rotations have completed three cycles.   The annual crops were managed with the latest technology and cultural practices with yields determined along with an estimate of both nutrient uptake and nutrient removal.  Following harvest and prior to any primary tillage, soil samples are taken to monitor changes in pH, soil nutrients, and other soil test parameters.  Grain crops have taken up and removed more nutrients and should have more rapidly affected soil nutrient levels.  With record yields for corn and soybean for the last few years, producers have removed record levels of soil nutrients and should be relying heavily on soil testing in order to maintain soil productivity.  Sulfur deficiency has been to surface in some areas and will continue to get worse unless supplemental fertilizer S is supplied.  The Centennial Rotation is providing useful information with respect to the utilization of the latest technology and the advantages to crop rotation.  Soil tests levels have not changed from some things such as pH but has others.