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Title: IMPACT OF DEEP RIPPING OF PREVIOUS NO-TILLAGE CROPLAND ON RUNOFF AND WATER QUALITY

Author
item Endale, Dinku
item Schomberg, Harry
item Franzluebbers, Alan
item Sharpe, Ronald
item Jenkins, Michael

Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 6/25/2002
Publication Date: 6/25/2002
Citation: Endale, D.M., Schomberg, H.H., Franzluebbers, A.J., Sharpe, R.R., Jenkins, M. 2002. Impact of deep ripping of previous no-tillage cropland on runoff and water quality. Annual Southern Conservation Tillage Conference for Sustainable Agriculture.

Interpretive Summary: The Parplow or Paratill is an implement that can be used to loosen soil without inversion with minimal disturbance of residue on the soil surface. It is an ideal implement to loosen dense soil layers that can sometimes develop below the surface in some conservation tillage systems, and which can lead to restricted plant rooting. The minimal disturbance of the residue on the surface is very important. The effect of this residue is what has made conservation tillage an economically and environmentally friendly farming system. The 2000 Crop Residue Management Survey by the Conservation Technology Information Center found that since 1990, the number of U.S. cropland acres planted without tillage has increased more than 200 percent to 51 million acres. We compared runoff from 4 small (1.3-2.7 ha) catchments that have been under no-till for at least ten years prior to and after paratilling two of them every fall since 1998. We found that runoff volume is significantly reduced from the catchments that have been paratilled, indicating that the loosening of the soil helped induce more infiltration and soil water storage. While the effect of paratilling on nitrate-nitrogen (NO3-N) and soluble orthophosphate (PO4-P) losses is not yet clear, losses of iron (Fe) and aluminum (Al) have been higher from the paratilled catchments, suggesting that any surface soil disturbance to a long standing no-till system could lead to immediate disruption of an established equilibrium. An on going severe drought reduced the size of the potential data set from the experiment.

Technical Abstract: Long-term conservation tillage practice might lead to soil compaction in some soils altering water and chemical movement and resulting in environmental problems. The problem gets exacerbated where restrictive horizons are near or close to the surface. Farming practices are needed that allow loosening of such natural or human-induced restrictive layers so as to reduce water runoff and associated off-site chemical losses. We have been monitoring surface runoff volume and associated nutrient concentrations, since 1998, from four catchments that have been under a no-till cropping system for at least ten years. We paratilled two of the catchments to 12-16 inches every fall during this experiment. We have found that runoff volume is significantly reduced from catchments that have been paratilled (P=0.06). While the effect of paratilling on nitrate-nitrogen (NO3-N) and soluble orthophosphate (PO4-P) loss is not yet clear, losses of iron (Fe) and aluminum (Al) have been higher from the paratilled catchments, suggesting that any surface soil disturbance to a long standing no-till system could lead to immediate disruption of an established equilibrium. An on going severe drought reduced the size of the potential data set from the experiment.