Cost of Legume Establishment Depends on Planting Procedure
Dr. Dirk Philipp, Assistant Professor, University of Arkansas
A study conducted at the University of Arkansas Division of Agriculture reveals differences in establishment costs and survival of annual and perennial legumes. In an experiment conducted over three years, researchers evaluated broadcasting and no-till drilling of crimson and white clovers into bermudagrass pasture at standard and low seeding rates. In addition, cattle were grazed either before or after planting to evaluate possible effects of cattle hoof action on clover establishment success and survival.
While legumes have many potential benefits, several challenges for a widespread use on beef farms in Arkansas remain. This is mainly due to their site-specificity, adaptation of commonly used legumes to a cooler climate than we have in Arkansas, uncertainty regarding the amounts of N recycled and rather drastic oscillations in legume occurrence over the years. Successful establishment, therefore, depends on getting off to a good start, and costs involved will determine whether producers should be encouraged to adopt certain legume establishment practices or not.
This is where this study comes into play. The combination of broadcasting followed by grazing was considered the low-cost alternative to planting into a short canopy using a no-till drill. Seeding rates for crimson clover were 20 and 10 pounds/acre, while for white clover rates were 5 and 2.5 pounds/acre. Planting took place each year in early October. Five days prior to and after planting, depending on the assigned grazing treatment, three mature cows were stocked in bermudagrass paddocks measuring approximately 100 feet 5 100 feet for each of the three replications. Bermudagrass paddocks used for this research were prepared by haying them about four weeks prior, leaving a canopy of 6-8 inches high.
Results revealed that rate of seedling survival depended on species, seeding rate and planting method, but effects of grazing were insignificant. The period between planting in the fall and the following spring determined seedling survival rates that ranged between 17% and 23%. A low seeding rate resulted in a higher survival rate (21%) than a standard seeding rate (17%). This could be attributed to increased seedling competition within the clover stands at standard rates. With respect to planting method, no-till drilling resulted in higher rates of survival than broadcasting in addition to a generally much higher actual number of seedlings in the field.
In terms of costs of establishment, this study revealed crimson clover was more expensive (about $40/acre) to plant than white clover (about $30/acre). Reducing the seeding by half did not necessarily reduce the cost of establishment by the same factor. For example, a no-till drill establishment for crimson clover resulted in $53/acre at a standard seeding rate, while the low seeding rate (half of standard) resulted in a $34/acre establishment expense.
Let’s compare that to broadcasting crimson clover. The results were $45/acre for a standard seeding rate and $27/acre for a low rate. If we take into consideration that the actual number of seedlings observed in the field was about twice as high after no-till establishment than after broadcasting, then I think this is a compelling case for doing the best when it comes to establishing clovers in bermudagrass pastures, namely using a no-till drill.
This may be especially true for small seeds such as white clover. The economists involved in this study showed that the cost per established white clover seedlings was much lower under no-till than broadcasting, which is partly due to lower survival rates of that clover species when using the latter establishment procedure.
Although there were no grazing effects observed, pasture canopies should always be managed before overseeding clovers. A pre- razing canopy height of about 6-8 inches, as in our case, may not be detrimental to clover establishment with modern no-till drilling machines, but the risk of establishment success may be substantially higher with a canopy that is even just a few inches taller. Therefore, canopy control is crucial next to maintaining a planting depth of no more than one-fourth to one-half inch. To achieve this, no-till drills have to be set up meticulously without cutting corners during the process. Seed tubes can easily become blocked through spider webs or old seed. Coated seeds that are used more and more nowadays especially can clog the mechanism when they become moist, as soil can plug the coulters whenever insufficient care is taken while operating the drill. Costs for canopy control can be minimized by stocking cattle at relatively high densities that should leave the canopy as low as 2 inches.