April
2018 weather. Meteorologists
and climatologists tend to relate current weather conditions to a 30-year
“normal”. Until 2021 our current weather
is related to conditions that occurred during 1981 through 2010.
According to the Midwest Regional Climate Center, In April
2018 NW MN counties have accumulated between 0.6 and 1.2 inches less
precipitation than normal (See map).
The
many dangers to planting before soils are fit. Even
though fields are warming and drying
out a little bit slower than normal, waiting until soil dries out and warms up
to begin planting corn and soybeans is advised.
Any compaction that is caused by planting into unfit soils
in 2018 may reduce a soil’s productivity and limit crop yield potential long after 2018 has
come and gone.
Some of the worst corn stands I have ever seen were the
result of people planting into wet soils. I was glad to have visited the field in the
pictures below alone so that the farmer or landowner weren’t present to hear my
audible gasp. In this field, planting into wet soils resulted in horrible side-wall
compaction. Roots then grew just in the furrow made by the planter and didn’t form
a nice root ball instead fanning out in the furrow (top R). There was also poor, uneven
emergence overall with gaps between plants so large that some plants actually
sent out tillers (top R). Even when damage is not as severe, wet or cloddy soil can
lead to poor seed to soil contact and poor stands (bottom).
Soybean plants have some ability to compensate for missing
neighbors by forming side branches. Corn stands, however, are particularly
vulnerable to uneven emergence. Research has shown between 6 and 9% of yield can
be lost when some plants emerge 1 ½ weeks later than their neighbors. Yield
losses can be greater than 20% when a portion of a stand emerges 3 weeks later
than the rest (Carteret al. NCR 344). Later emerging plants are unable to compete with larger
neighbors that can access more sunlight, water and nutrients due to their
comparatively larger size and are often barren. The bottom line: yields are
often similar or higher when planting is simply delayed until soils are drier.
Even if fields are dry enough to plant into, planting into
low temperature soils is risky. Seeds passively absorb water from the soil
around them and are particularly vulnerable to cool soils during the first 24
hours after planting. If seeds absorb water colder than about 50 degrees, cell
damage can lead to poor seedling vigor or even death (Licht,
2014). Both corn and soybean seed can germinate at soil temperatures
around 50 degrees, but germination is really slow. Plants aren’t warm-blooded and
have to rely on the heat in their environment to drive the cellular processes
needed for growth and development.
While the network of NDAWN
weather monitoring stations can give us some clue as to soil temperatures around
the region, there is no substitute for checking soil temperatures in your own
fields as differences in topography, crop residue, water-holding capacity and
soil type can affect soil temperature.
Some farmers perennially battle seed and
seedling diseases in certain fields. A seed is particularly vulnerable to soil-borne
pathogens when it absorbs water and low temperatures slow germination and emergence.
Seed often comes coated with seed treatment fungicides. But these expensive
inputs can only protect the seed for so long (~21 days) before they begin to lose
efficacy. Planting into cold, wet soils can put seeds and seedlings at risk,
even when they come armored with seed treatment fungicides.
Bottom line: with warmer air temperatures and windy
weather, soils are drying quickly. To set up our 2018 crops for success, it is
important to remind ourselves to be patient and wait to plant until soils
are drier and warmer.
