Developing Tillage and Rotation Systems in NC – General Assumptions

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Best Management Practices for Crop Rotations

Peanut – 3 non-legume crops between peanut crops (following soybean behind peanut is generally acceptable but not preferred)

Tobacco – 2 non-legume crops between tobacco crops

Cotton, Corn, Grain sorghum, Soybean, and Wheat can be grown for two years in row without substantial yield loss. However, in general, for each year these crops are grown in a row the following percent yield loss can occur (Corn and Grain sorghum, 10%; Cotton, 5%; Soybean, 8%; Peanut, 25%; Tobacco, 12%; Wheat, 2%). Note that this estimate can change dramatically (decrease in yield or increase in percent yield loss) based on initial diversity and pressure of pests in the field. Nutrient balance also needs to be considered (“mining” by individual crops over and extended period of time.) Cost of production, primarily pest management, will increase with increasing number of years fields are planted in the same crop. Yield potential can be maintained in some instances but only as production costs increase. The major impact of poor rotation is observed during the first 3 years after which yields may not decrease substantially with continued “poor” rotation but will remain at a productivity level below potential.

Yield loss will be compounded after two or three years of repeating the same crop in the same field. For example, soybean yield could follow the following trend in yield loss.

Year 1 – 50 bu/acre;
Year 2 – 46 bu/acre;
Year 3 – 46 bu/acre;
Year 4 – 46 bu/acre;
Year 5 – 46 bu/acre

Total loss over 5 years of continuous soybean 32%.

Crop Response to Reduced Tillage versus Conventional Tillage

Yield of corn, grain sorghum, cotton, and soybean are generally the same in both systems when managed properly and can fluctuate depending on the season.

Yield of wheat on coastal plain soils can be lower in reduced tillage than yields in conventional tillage but will be similar on Piedmont soils.

Peanut yield is generally similar in both systems on coarse-textured soils while yields are 8% higher on finer-textured soils when peanut is planted in conventional tillage compared with reduced tillage.

Tobacco yield is generally 20% lower in reduced tillage compared with conventional tillage.

Note: The statements above are relative to a single year or group of years, especially in transitional years. However, long-term impacts of tillage, especially with respect to soil loss through erosion, can be substantial. For example, grain and cotton yields in the Piedmont might be the same in any given year comparing reduced and conventional tillage; however, long term sustainability is generally higher in reduced tillage systems because soil resources are protected in reduced tillage. In the Piedmont, but also to a degree in the Coastal Plain, soil tilth with long term, well managed no till is also a significant long term advantage. In some Piedmont fields, long term no till provides a consistent 7% yield increase over conventional tillage.

Article first appeared as North Carolina Peanut Note (PNNC-2013-015)