Mary Miller, Bob Goodman, LeAnn Self-Davis, Randy Raper, and Wayne Reeves

In row-crop production, tillage usually improves the capacity of the soil to store water and nutrients. In recent years, agricultural implements capable of soil tillage in permanent sods, including pasture and hay lands, have become available. An AAES study has been comparing the effects of two renovation tillage implements on productivity of tall fescue-bermudagrass pasture cut for hay. Results suggest that the effectiveness of renovation may depend, in large part, on soil moisture conditions.

Little previous research information has been available relative to the effectiveness of renovation tillage for enhancement of forage yield or infiltration of rainfall and/or nutrients. Limited data from other regions has generally shown no vegetation response to renovation tillage. In some cases, yield decreases have been reported. The study examined responses of hayland to two types of tillage implements.

At least two basic types of tillage implements are commercially available for use in pasture renovation. The Aer-Way Renovator is an example of a ground-driven rolling-tined aerator/cultivator that resembles “pitting” implements used on rangeland. It is being marketed as an implement to improve pasture productivity through increased retention of rainfall and nutrients. The second class of implements includes the Paraplow or the more recently available Paratill, which loosen the soil by relatively deep tillage but do not invert it.

The study was conducted on Hartsells fine sandy loam soil at the Sand Mountain Substation, Crossville. Livestock were excluded from a two-acre area of a pasture that had been continuously used for grazing cattle since 1981. The experimental treatments were: 1) renovation with the Paraplow, 2) use of the Aer-Way pasture renovator and, 3) no renovation. Each treatment was replicated three times. Renovation treatments were applied each spring for three years. Researchers monitored hay yield and quality, vegetative cover composition, and root length density.

Cattle were excluded from plots so that hay yield data could be collected and because the presence of cattle on the land would have required more frequent renovation treatments because of soil compaction. Penetrometer measurements taken on soil that had been grazed indicated that soil compaction from cattle recurred soon after renovation, while the effects of renovation on soil physical properties continued for some time on plots where cattle were excluded.

No consistent yield increase resulted from annual renovation (see graph). The only statistically significant finding was that the yield of the Paraplow plots was significantly less than the Aer-Way or control plots in the June 1996, measurement. No other differences reported in this study were statistically significant at the 10% probability level. There were yield increases some years, and yield decreases in other years when compared to no renovation tillage. While limited replications and short duration of the experiment make statistical comparisons difficult, there were certain weather characteristics in each year that might have resulted in the slight yield advantage apparently evident for either of the renovators or, indeed, for the control plot.

Yield data from renovation studies, 1994-96.

Weather patterns in 1996 were similar to the previous year, with dry weather early in the year, then seasonal mini-droughts during the summer with adequate moisture only periodically. In April, yields were very low, and none of the three treatments had any advantage. In June (in an extra measurement) moisture conditions had improved and yields were higher, but growing conditions were not favorable enough to allow the deeper-tilled Paraplow plots to recover from any root damage.

Yields in the fall of 1996 were approximately equal for all treatments, and cumulative yields for the year were comparable to 1994. The difference between 1994 and 1996 was that the Paraplow plots seemed to show a slight yield advantage in 1994, but 1996 yields on the Paraplow plots seemed to be slightly lower than either the control or Aer-Way plots.

Prelimary interpretation of these results seems to indicate that damage to root systems observed with the Paraplow may be a factor in reduced forage production under drought conditions such as those experienced in 1995 and early in 1996. However, soil loosening at a deeper depth that occurs with Paraplow treatment may be a factor in increased forage production in high moisture conditions, such as were experienced in 1994. Renovation with the Aer-Way appears more likely to favorable affect forage production under droughtier conditions. These hypotheses mau be further tested when results of the companion experiment, where cattle were allowed acces to treatments, become available. Further, additional experiments that alter the renovation regimen may also be warranted.

These preliminary data indicate a yield increase for patures treated with renovation tillage may occur under some environmental conditions. The differences reported in this study were not statistically significant, and further research is warranted, but if the data are correct, renovation could provide positive net returns to hay producers. For example, if hay price was $60 per ton, and if renovation resulted in a 10% increase in production, break-even renovation total cost would be in the range of $6-9 per acre. Unfortunately, achieving such a low total cost of renovation is unlikely for most Alabama producers unless renovators can be held in some form of shared ownership to hold fixed costs per acre for renovation at a very low level.

Miller is an Assistant Professor of Agronomy and Soils; Goodman is an Associate Professor of Agricultural Economics and Rural Sociology; Self-Davis is a Graduate Student of Agronomy, Univ. of Arkansas; and Raper and Reeves are Research Scientists with the USDA-ARS National Soil Dynamics Lab.