Within the region, minimal differences have been observed between April and May planted soybeans, although cooler weather and disease may reduce yields with earlier planting. Another issue uncovered in recent DSB research projects is the effects of Al and Fe uptake on reducing early planted soybean yields. One way to reduce the effects of these metals is maintaining a
higher soil pH, reducing the solubility of Al and Fe. By increasing soil pH, soybean producers may find that earlier planting on our coastal soils can take advantage of a longer pre-solstice growing season and obtain greater yields.

Alternatively, higher pH may reduce the availability of other metal micronutrients, including Mn, Zn and Cu. It may also give rise to greater edge site cation exchange capacity, allowing for greater leaching of B and SO4 from the soil surface. Rather than having a net sum reduce the effectiveness of liming, we must determine the liming effects on all nutrients taken up in these
soils.

1) Lime soils at five rates to observe soybean growth and yield
2) Plant soybeans at two different timings within the lime plots to observe Al uptake.
3) Compare the effects of lime and planting timing on yield.

Using a regional farmer field, we will establish 10 by 30-foot plots to receive lime treatments as a randomized complete block design (RCBD). There will be five lime rates (0, 0.25, 0.5, 0.75, and 1.0 tons acre-1), two planting timings (April and late May), and three replications for a total of thirty combined plots. Lime treatments will be hand applied in the spring prior to soybean
planting. Soil samples will be taken prior to lime application to establish each plots baseline. Soybean tissue samples will be taken at V3 and R1 to establish nutrient uptake over the season. All samples will be submitted to the UD soil testing lab for analyses. Yield will be collected at the end of the growing season using a plot combine. Tissue nutrient content will be correlated to yield and initial soil nutrient levels. Using SAS statistical software, we will compare the plot data
as a factorial RCBD to determine treatment effects. Results will be reported to the board as well as at regional extension meetings.

Updated August 8, 2024:
A section of a rye cover crop was terminated in March 2024, plots were established and then limed followed by a turbo-tilled to incorporate into the upper 2 inches of the soil. The first soybean timing was planted in early April 2024, and the second timing was planted in late May 2024. Due to persistent deer feeding, a fence was placed around the plots for two weeks, limiting feeding to outside the plots so they could recover. At this point in the season both April and May planted soybeans have reached reproductive growth stages, so that tissue samples from both vegetative and the R2 growth stage have been sampled and placed in a drier. Pre-plant soil samples were taken in April. Soybeans have been irrigated earlier than expected due to drought conditions, and weed control has been performed to prevent herbicide resistant weeds from growing in the plots. Drone flights have been performed over the plots before and during the project duration.

Soybean farmers will be able to apply the lime necessary for both maximum yield benefits while limiting aluminum uptake into the plant.