Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2011
Publication Date: 1/2/2012
Citation: Gesch, R.W., Archer, D.W., Spokas, K.A. 2012. Can using polymer-coated seed reduce the risk of poor soybean emergence in no-tillage soil? Field Crops Research. 125:109-116.
Interpretive Summary: Not tilling the soil after crop production (i.e., no-tillage) and leaving it this way until the next crop is grown has both money savings and environmental benefits. No-tillage prevents soil erosion and improves soil health, which helps to sustain agricultural productivity of the soil for years to come. However, no-tillage is not a popular practice in the northern Corn Belt region because it takes longer for the soil to warm and dry in the spring than if deep tillage such as moldboard plowing is used. Therefore, farmers have to wait longer before they can plant no-tillage fields and that can mean lower yields. If farmers plant soybean into soil that is too cold, it can cause the seed to be weakened and die, leading to poor plant stand establishment, which further results in lower yields. A new temperature-activated polymer seed coating has been developed that potentially can protect seed from cold temperature injury even if it is planted early into cold soil. This seed coating may be a good tool to promote greater use of no-tillage in the northern Corn Belt. We tested the potential benefits of the seed coating by planting both polymer-coated and non-coated soybean seed (control) very early and at a more normal time in a no-tillage system. We also tested the coating on both a short and longer season soybean variety for the region of the study. We found that when seed were planted into cold soil in a no-tilled field and the seed sat in the ground for a long time before emerging, the polymer coating did indeed protect the seed and resulted in much better plant stands than non-coated seed planted at the same time. Results from this study do indicate that temperature-activated polymer-coated seed may take some of the risk out of planting soybean early into no-tilled soil. This research will help crop consultants and university extension specialists decide if this technology will benefit farmers in their region and this technology should help promote the use of no-tillage in the northern Corn Belt region.
Technical Abstract: Adoption of no-tillage in the northern Corn Belt has lagged behind other regions because of slow warming and drying of soils early in the spring coupled with a short growing season. Cold, wet soil can lead to seed damage resulting in poor stand establishment. Because of slow warming and drying, no-tilled soils are typically sown later than conventionally-tilled systems thus often requiring the use of early maturing crop cultivars. Temperature-responsive polymer seed coatings might allow soybean [Glycine max (L.) Merr.] to be sown earlier than normal under no-tillage while protecting seed against damage caused by cold, wet soil and perhaps allow the use of later maturing cultivars. These ideas were tested during 2005 and 2006 in west central MN on a Barnes loam no-tilled soil previously cropped in corn (Zea mays L.). Polymer-coated seed of a maturity group (MG) 0 and I soybean were sown as early as possible (early- to mid-April) and at an average recommended time (mid-May) for the study site. Only in 2005 did the polymer coating significantly influence emergence (p < 0.0001), where maximum emergence of early sown polymer-coated seed of the MG 0 and I cultivars was 51 and 35% greater than their uncoated counterparts. Conversely, for the average sowing date in 2006, under unusually dry conditions, the polymer coating slowed seedling emergence and reduced maximum emergence, although yield was not affected. The MG I soybean out yielded the early cultivar in both years, but sowing date did not have a significant effect either year. Results indicate that temperature-activated polymer-coated seed may reduce the risk of poor stand establishment in no-tilled soil in instances where low soil temperatures cause seed to remain in the soil for an extended time before emerging.