April 16, 2010

After learning about Dr. Jim Specht’s archive/-/asset_publisher/VHeSpfv0Agju/content/research, producers in the Greater Quad County and Nebraska Soybean and Feed Grains Profitability Project archive/-/asset_publisher/VHeSpfv0Agju/content/research groups were curious as to how early planting dates would work on their farms in 2008-2009. They conducted on-farm archive/-/asset_publisher/VHeSpfv0Agju/content/research of early and late planting dates at a number of sites and found that early planted soybeans consistently outyielded later planted beans, even with cooler springs.

2008 Studies

The cold, wet spring in 2008 was a challenge as it was hard enough getting corn in at a decent time in 2008. In 2008, four producers conducted the soybean planting date study in irrigated no-till or ridge-till conditions on 30-inch rows. Early planting dates ranged from April 23 to April 30 and later planting dates ranged from May 14 to May 19.

At all sites in 2008, the early planting date out-yielded the later one. At two locations (six replications), a study looked at early/late planting dates and rates of 90,000, 120,000, 150,000, and 180,000 seeds per acre. Average early planting yield was 1.8 bu/ac better than the late planted soybeans. Two locations (containing a total of 15 replications) were planted at 150,000 with the early planting yielding 3.5 bu/ac better than the late.

2009 Studies

The cold spring in 2009 also was a challenge for the early planting dates as it led to more days than normal from planting to emergence and then to V1 (when the node accrual of one new node every 3.7 days kicks in). The early planting dates lost their quick-start advantage, but, like the later planted soybeans, benefited from the generally cool summer and good growing conditions.

In 2009, we had two rainfed locations (Saunders County on 15-inch rows and Clay County on 30-inch rows) and four irrigated locations. The irrigated trials were conducted on 30-inch rows in ridge- or no-till. All irrigated early planting dates were from April 24 to April 27 and later plating dates were from May 15 to May 20. For the rainfed studies, the early planting dates ranged from April 27 to May 3 with the later planting dates from May 18 to May 21.

In spite of the cold spring, the early planting date out-yielded the later planting date at all sites, except the dryland Clay County site which was a wash due to major jackrabbit infestation. There was no statistical difference between the early and later planted yield for any location in 2009 and the early planted soybeans out-yielded the later dates by 1-2 bu/ac. Combining the irrigated data (total of 15 replications), the early planted soybean yields were statistically significant at both the 95% and 99% levels and yielded 1.4 bu/ac better.

Seed Treatments

Both the early and later planted beans were treated with a combination of fungicide and insecticide seed treatments to prevent problems with seedling diseases and bean leaf beetles on the early planted soybeans. While we would recommend this for early planted soybeans, it was also applied to the later planted seed for archive/-/asset_publisher/VHeSpfv0Agju/content/research consistency. If treatment costs an estimated $9.50/ac and the soybean price is $9.00/bu, the early planted yield increase would need to be 1.1 bu/ac to break even.

Recommendations

Based on Dr. Specht’s archive/-/asset_publisher/VHeSpfv0Agju/content/research and these producers’ on-farm archive/-/asset_publisher/VHeSpfv0Agju/content/research, early planting does seem to provide a yield advantage, even in cold springs. A broad recommendation would be for the southern two-thirds of Nebraska to begin planting soybeans the last week of April and the upper third begin planting the first week of May. For planting rainfed soybeans early, it is recommended to extend the growing season to take advantage of August rains. Change to a quarter or half longer relative maturity (RM) than you would use for a later May planting. For example, in a southern Nebraska rainfed field you might change from a 3.0 to a 3.3 or a 3.5 relative maturity so that the seed-filling period is more likely to occur when temperatures are cooler but before the first fall frost.

While we can’t control the weather, planting soybeans early allows you to take advantage of warmer springs and weather conditions that favor high yielding soybeans. With early planting we recommend treating the seed with an insecticide and a fungicide. If your field has a history of Sudden Death Syndrome (SDS), we recommend not planting early as the fungus causing SDS is favored by cool soil conditions during early planting.

Resources

• View the archive/-/asset_publisher/VHeSpfv0Agju/content/research reported in this article in more detail.
• Learn more about conducting archive/-/asset_publisher/VHeSpfv0Agju/content/research on your farm or view other archive/-/asset_publisher/VHeSpfv0Agju/content/research reports from on-farm archive/-/asset_publisher/VHeSpfv0Agju/content/research studies in the Farm Research site in CropWatch.  

Jenny Rees
Extension Educator, Clay County