Impact of Late Planted Soybeans - June 25, 2009
[Title Slide – Impact of Late Planted Soybeans, Dr. Jeremy Ross, Soybean Agronomist , Number 5 - June 25, 2009, Your Arkansas Soybean Podcast, University of Arkansas Division of Agriculture, Arkansas Soybean Promotion Board]
[Jeremy Ross standing in a field with a tractor.] I’m Jeremy Ross, Soybean Agronomist with the University of Arkansas Division of Agriculture, and today we are going to talk about the impact of late planted soybean.
[Line chart showing the effect of planting date on irrigated soybean yield by maturity group] [Slide – Late Planting Can Impact Yield - Research suggests that planting soybeans late may result in yield loss; Yield loss potential after June 15 – 1% - 2% per day; After July 1 as much as 2% - 3% per day. Picture of soybean pods.] Research findings suggest that planting after June 15 results in a 1 to 2 percent yield loss per day, with the yield loss potential increasing to 2 to 3 percent per day after July 1. [Slide – Minimize Late Planting Yield by – Changing variety; Selecting a variety with growth habits for a shorter growing season; Selecting a good herbicide; Adjusting row spacing and seeding rate. Picture of soybean pods. ] Some of the yield loss associated with late planting can be minimized by changes in variety, variety growth habits, and herbicide selection. [Picture showing soybean plant rows with a tape measure – decrease row spacing to 20 inches or less.] Additionally, research shows that decreasing the row space to 20 inches or less and [Picture showing soybean rows with a tape measure – increase seeding rate by 10% - 15% 8 seed per foot to 10 seed per foot.] increasing the seeding rate by 10 to 15 percent will help offset yield losses and decrease the number of competitive weeds. [Picture of a soybean field]
[Slide – Planting After July 15 - Not recommended; Some MG IV and MG V can produce mature seed, if emerged by August 1; Plant height and grain yields will be greatly reduced. Picture of soybean pods.] Plantings after July 15 are not recommended due to a greatly shortened growing season although some late MG IV and V varieties usually have enough time to produce mature seed before a fall frost if emerged by August 1. Plant height and grain yields will be greatly reduced in the July plantings.
[Slide – Late Planting Impacts - Number of days to flowering; Amount of time available for vegetative plant growth and development. Picture of soybean pods.] Soybean plants are photoperiod sensitive. Late planting impacts the number of days to flowering, the amount of time available for vegetative plant growth and plant development, which all are necessary for good yields. [Slide – Yields are reduced because – Poor stands due to hot soil temperatures; Short day lengths; Early flowering and reduced vegetative growth. Picture of soybean pods.] Planting too late can reduce yields because of poor stands due to excessively hot soil temperatures or because day lengths are too short. Short day length may result in plants flowering early and having reduced vegetative growth.
[Slide – High Quality Seed is Important – Helps to establish a good stand of vigorously growing seedings. Picture of soybean pods.] Obtaining soybean seed of acceptable quality for planting is highly recommended. This will help ensure establishing an optimum stand [Picture of a soybean field] of vigorously growing seedlings. [Slide – Seed Vigor is Key Especially when – Planting is delayed into June and July; Soil moisture is marginal; High soil temperatures occur. Picture of soybean pods.] As plantings are delayed into June and especially into July, the vigor of the seed becomes more important if marginal soil moisture and elevated soil temperatures occur. [Slide – Late Planting and Seed Quality – Seed with less than 80% germ may produce poor stands; Seed vigor, measured by the Accelerated Aging test, may have declined to 50% or less. Picture of soybean pods.] Seed that has less than 80 percent germination late in the planting season may produce poor stands [Picture of a soybean field showing skippy stands due to poor seed quality.] especially if there are significant adverse conditions at planting due to low seed vigor. [Slide – Late Planting and Seed Quality – Seed with less than 80% germ may produce poor stands; Seed vigor, measured by the Accelerated Aging test, may have declined to 50% or less. Picture of soybean pods.] Seed vigor, as measured by the Accelerated Aging test, may have declined to 50 percent or less by late June and July.
[Slide – Late Planted Soybeans – Limited root systems that can’t withstand long periods of drought; If planted by June 15 and irrigated, 50 bushels per acre or more; Dryland fields may have stand establishment problems. Picture of soybean pods.] Late-planted soybeans have more limited root systems and cannot withstand long periods of drought. With irrigation, yields of 50 bushels or greater are possible with proper management if planted by June 15. [Picture of a soybean field with a poor stand establishment] A late planted dryland soybean field is often at high risk for stand establishment due to inadequate soil moisture in mid- to late June. [Slide – Late Planting/Short Season increases all stresses to crop. Picture of soybean pods.] Also, the shortened season associated with late planting dates intensifies the effect of any stress on the crop.
[Slide – Control Weeds – Good burn down program needed; Lots of weeds could mean yield loss. Picture of soybean pods.] To combat weed problems, a good burn down program is needed to kill existing weeds at planting to allow soybean to germinate and insure a good stand. Too many weeds competing with soybean could result in yield losses.
[Slide – Monitor for Insects and Diseases – Late planted fields at high risk; Scout weekly during reproductive growth stages; Apply insecticides/fungicides only if pest pressure will have economic impact. Picture of soybean pods.] Late planted soybean fields are at a higher risk for attack by late season insect and disease pressure. Fields should be scouted weekly during the reproductive growth stages to monitor for pest pressure. Applications of insecticides and fungicides should only be made if the pest pressure is at an economic threshold.
[Narrator] Your Arkansas Soybean Podcast is a production of the University of Arkansas Division of Agriculture and was funded in part by the Arkansas Soybean Promotion Board. For more information on soybean farming in Arkansas contact your local county Extension Office. [Title slide - For more information contact your local county Extension office. Your Arkansas Soybean Podcast, University of Arkansas Division of Agriculture, Arkansas Soybean Promotion Board]