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).
