Submitted to: Forage and Grazinglands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2005
Publication Date: 9/13/2005
Citation: Bartholomew, P.W. 2005. Comparison of Conventional and Minimal Tillage for Low-Input Pasture Improvement. Online. Forage and Grazinglands doi:10.1094/FG-2005-0913-01-RV. Available: http://www.plantmanagementnetwork.org/pub/fg/review/2005/minimal Interpretive Summary: Minimal-tillage techniques allow planting of seed without the cultivation that is necessary with conventional methods of sowing. Less cultivation means that farmers can save time and need less field equipment for sowing crops, and therefore reduce their costs of production. Minimal tillage may be particularly valuable for small livestock farmers with limited time and equipment, or on land that is prone to soil erosion when cultivated. When pasture is resown by conventional means, there may be significant production loss, compared with undisturbed pasture, during the ground preparation and establishment period. This production loss will be increased if the new seeding fails to establish. However, because minimal-tillage does not have to destroy existing pasture, there is a possibility that surviving old pasture will reduce the potential loss of production, in the event that a new seeding fails to establish. A study of scientific literature was made to review the state of knowledge on the use of minimal tillage for pasture improvement, and on its usefulness to small and resource-poor farmers. If minimal tillage is used simply as an alternative to conventional cultivation and sowing to replace an old pasture with a new seeding, subsequent forage ouput is reduced by an average of approximately 10%. However, when minimal tillage is used to plant new seed without destroying the existing pasture, there is usually a gain in year-round forage yield, if the new crop and original pasture have complementary growth patterns. There is no obvious difference in the persistence of pastures established by minimal tillage, or by conventional means. Research is needed to evaluate the risk of establishment failure in reseeded pasture and the impact of establishment-year production loss on long-term pasture output, compared with undisturbed pasture.
Technical Abstract: Farmer decisions on pasture improvement strategies are likely to be driven by considerations of cost, risk and productivity. Minimal-tillage seeding practices offer reduced cost for introduction of new seeds, but their impact on risk of establishment, pasture persistence and productivity, compared with conventional tillage and sowing, is less certain. Review of literature shows that the average forage productivity of crops established by minimal tillage is approximately 10% lower than that of comparable crops established by conventional tillage. Establishment of forages is generally less effective when minimal tillage is used, but established plant populations and forage yield can be improved by herbicide suppression of resident vegetation prior to minimal tillage seeding. Data available do not show a clear effect of planting method on persistence, and the risk of stand failure in reseeded pastures is not well-defined. In low-input farming systems minimal-tillage seeding is likely to be of greatest value when it is used to plant forages that complement, rather than replace, an existing crop, as this usually provides a gain in total annual forage output, and an improvement in seasonal distribution of production. The potential of minimal tillage seeding for mitigating the effects of stand failure and production loss during the establishment period, and thereby increasing cumulative productivity over repeated cycles of reseeding, compared with conventional tillage practices, requires further study.