Many of my previous articles have touted planting soybeans early in the midsouthern US to achieve greater yields and returns. However, there are other reasons for planting early that, if not achieved, may result in increased costs and/or lost income.
When planning for early planting, producers select top varieties from an early maturity group. If planting is delayed to late May and beyond, these early-maturing varieties may be unsuitable. Therefore, it is probable that the already-purchased seeds of early-maturing varieties will have to be replaced with those of later-maturing varieties, resulting in additional cost.
In stale seedbed late plantings, there probably will be additional preplant herbicide weed control costs beyond those for the normal late February/early March application of burndown herbicides. Where tillage is used to prepare a seedbed for plantings that are delayed into late May and beyond, additional operations likely will be required to kill weeds that emerged since earlier tillage or application of burndown herbicides. According to the Mississippi State Budget Generator, disking and field cultivation costs are about $8 and $6 per acre, respectively.
Planting late results in later maturity and the concurrent risk of detrimental late-season insect infestations (See Aug. 18, 2006 Delta Farm Press). This results either in increased cost associated with more spraying, or yield loss if control measures are not applied. A rule of thumb is that early plantings will require treatment for stink bugs, but only rarely will require treatment for foliage- and pod-feeding insects. Late plantings will require treatment for stink bug control and likely a treatment for control of foliage- and pod-feeding worms.
Planting late results in later maturity and the concurrent risk of detrimental late-season effects from drought. Late plantings generally require more irrigation, and this translates to $8 to $10 per acre higher costs. Escalating fuel prices will increase this extra cost for more irrigation of late-planted soybeans.
Harvest of early-planted soybeans in the midsouth generally occurs from mid-August through mid- September when soil usually is dry. Later-maturing varieties used in late plantings will be harvested in October and November when there is a greater probability of rain and wet soil. Harvesting at this time usually results in some level of rutting. If tillage is required to remove these ruts the following spring, the opportunity for an early planting date may be missed.
Weather and pest problems that often afflict late-planted soybeans may lead to soil conditions or yield potential that results in the crop not being harvested. According to the National Agricultural Statistics Service, an annual average of 2.8% or 178,000 acres of the Arkansas, Louisiana, Mississippi, and Tennessee soybean crop was not harvested from 2001 through 2005. It is likely that most of this unharvested acreage was late-planted. This can translate to an annual loss of over $25 million income to the region.
The threat of Asian soybean rust to the midsouth soybean crop was a major concern in 2005 and 2006. However, rust was not detected in soybean sentinel plots in the extreme southern part of the region until late July of both years. Its progression was minimal through mid-August. By this time, soybeans in early plantings were past the stage (R6 or full seed) for measurable damage from rust, or had been harvested. Thus, it appears that early plantings will avoid late-season rust infestations when the inoculation source is from re-introduction of the rust pathogen into the major soybean-producing areas of the US. Conversely, late plantings likely will require treatment to prevent or control anticipated late-season rust infestations.