Tuesday, July 10, 2012

Getting Additional Forage This Fall

Dan Undersander and Shawn Conley

Some farmers need additional forage and want to plant a second crop following wheat or corn taken early for silage due to drought.  As of July 15, the best option is to wait until after August 1, and then consider planting oats with or without peas.
While corn may yield as well as any other crop, it is more expensive to plant and will need a frost to dry down the forage sufficiently for ensiling.  Sorghum-sudangrass, sudangrass and millet require 80 degree or higher temperatures for significant growth.  Hot as it may seem now, those temperatures are not likely to occur on a daily basis after Sept 1.  So little fall growth will occur and yield will be low.
Oats, planted the first week of August can be expected to produce 2.5 to 3 t/a dry matter in an average year.  Other small grains will generally produce about half as much since they do not put out a stem.  Adding 20 lb/a peas to the oats will increase palatability but will not affect yield. 
Coblentz, USDA Dairy Forage Research Center, found that a late-maturing forage cultivar (ForagePlus) produced maximum annual yields ranging from 2 to 3.5 t DM/a.  Because the forage cultivar matured slowly it was better able to respond to sometimes erratic late-summer precipitation. These types mature later and produce more tonnage of quality forage.  If seed of a forage type is not available, plant a late maturing oat variety.  After the first week of August use of a forage type oat will provide less advantage and grain-type cultivars often may be better management choices.
The fall planted oat is higher in forage quality than spring planted oats.  Research at the University of Wisconsin by Albrecht found that maturation of summer-sown (August) oats was delayed, resulting in 10 to 15% less neutral detergent fiber (NDF), 18% greater digestibility, and 250% more water soluble carbohydrate than spring-sown oat.
The recommendation would be to plant 1.5 to 2 bu oats/acre (with or without peas).  Soil test to determine if sufficient residual nitrogen remains for the oat crop following the drought-reduced corn crop.  If not, fertilize with 60 to 70 lb nitrogen per acre at planting.  It is also important to check for any herbicide plant back restrictions prior to planting the oat or oat/pea mixture.  Planting should occur during the first week of August as earlier planting will result in earlier maturation and reduced yield. Selection of a forage-type cultivar likely will result in superior yield and nutritive value for planting dates as late as the first week of August.

Figure 1. Concentrations of total digestible nutrients (TDN) from oat forages planted on August 1 and harvested on five dates throughout the fall at Marshfield, WI (Coblentz et al., 2012).