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ISSUE 11   JULY 15, 1999

 

IMPLICATIONS OF THIS SEASON’S WET WEATHER ON SOIL FERTILITY-

    I am betting that the situation that many producers are in around the state with late planted crops
and abandoned fields at this large scale is unique. I also suspect that the water received this spring in
the western part of the state is most unusual. Therefore I think it is appropriate to share some thoughts
regarding how to cope better with next year starting with this year.

Drainage issues-

    The best way to begin addressing drainage issues is right now when water is on the fields or you
at least remember where the wet spots are. In traditional dryland country (NW/SW) many producers
were immobilized this spring because they had no idea where their wet spots were and stuck the tractors
multiple times trying to figure them out. Map them now. Next time its wet, it will be wet in the same
spots and instead of abandoning fields in disgust and frustration, these areas can be avoided (consider
GPS). Maybe it will be 10 years before its wet in Amidon again. But that’s what people in NE North
Dakota thought in 1993.

    Talk to the local NRCS about thoughts you have on how to drain certain areas. There may be ways
that water can be drained off fields that you have not thought of. Sometimes, wetlands can be moved to
other areas to allow greater drainage from other parts of fields. Consider taking aerial photos of your
fields when its wet to illustrate the problems and possible solutions. Aerial photos are best taken fairly
high in the air, so that entire quarters can be shot straight down to avoid pasting and perspective issues.

Soil sampling-

    I was impressed when I arrived in 1994 that about 1/3 of North Dakota acres were soil sampled each
year for N. However, now that I have been around for awhile I am concerned that the percentage has
not increased. The excuses are numerous and some justifiable. The main concern by progressive producers
is that the composite soil test is not representative of the field. That can be very true, and no more truer than
in a wetter year. However, that does not mean that soil testing should be abandoned. It means exactly the
opposite. If soil sampling is not conducted, what’s the alternative? Doing the same thing you always did
before-which means that much of the field will be fertilized incorrectly.

    So what should a person do? Sample in a landscape-based manner. Hilltops (bumps near Bottineau),
slopes and depressions all sampled separately. Is it perfect? No. Can there be mistakes? Yes. Is it better
than a composite sample or fertilizing like you did in 1991? You bet it is! The cost should not be much
higher than taking a composite test. Instead of 20-30 sample cores per field to try to smooth out the extreme
highs and lows of a field and come up with a good field average, about 12 cores per landscape zone should
be sufficient. If there are unusual areas that you are curious about, don’t ignore them, sample them separately.
You spend good money on these areas every year, isn’t it time to figure out what’s wrong ( and if it’s
something you can’t control wouldn’t permanent grass be a good idea?)?

    Soil sampling is something that some growers may want to do themselves. A soil probe that goes down
to 2 feet costs about $50. Depending on the type of soil, a replaceable tip-style probe may be best (especially
in rocks) although I prefer the one-piece Hofer soil tube myself. It doesn’t seem to plug up as much for me in
heavier soils. I go through about 10,000 soil cores a year with mine and it usually lasts about 2 years.

    For those of you that are uncomfortable with soil sampling, there are crop consultants and ag-supply
dealerships gasping for any kind of business in the wetter areas of the state. I bet they have time to sample
this year. In fallow areas, beginning in mid-late September is probably as soon as you would want to
begin. Following small grains, as soon as the grain is off in August/September would be alright. There is
little N increase in the soil following a small grain crop. Following canola or another broadleaf crop, waiting
until the middle of September is probably best to allow the most easily deteriorated leaf tissues to give up
any excess N before sampling.

Fertilizer Application Timing-

    This year was a good indicator of how quickly and how deeply N can move when excess water is in the
field. So this fall, do not let convenience of application get ahead of the calendar and soil temperature. Wait
until at least the end of September even if it appears like cold weather is here or nearby. If the soil temperature
is warm until mid-October, wait until those morning soil temperatures reach at least 50 degrees before
beginning. Otherwise, the risks of loss are going to be there next year. I leave it to you to determine how
much they hurt this year after you take the grain in to sell. I suspect protein levels will not be high.

    What about sulfur for canola? Sulfur leached below the rooting zone in many fields this spring. It leached
regardless of whether the sulfur was applied in the fall or spring. However, over the years, the spring applied
materials will tend to leach less than fall applied. Will applying more sulfur in the spring be easy to do? No.
Do many fertilizer companies have the horses to apply the thousands of acres of sulfate fertilizers in a short
spring? Probably not. Is this the best thing to do agronomically? Yes. So figure out a way to apply sulfate
fertilizer (not elemental) in the spring at planting time by switching planter openers to something with seed
and fertilizer separation and thereby reducing your risk of seed injury and leaching losses.

General comments regarding this usual year-

    I am not sure that during my 18 year career in the fertilizer business that there was a year quite as nasty
as this one has been for some areas of the state, but I have been through wet cycles, dry cycles, crop
failures, PIK programs that took the crop acres in the county away from us and many other challenges.
I found that as the challenges grew, the need for more and better information grew. Try to get on top of as
many pieces of the farm operation as possible. Question everything. Rethink everything. Talk to suppliers
(and financial suppliers, too). Things will turn around. The way that this time is handled can put a grower into
position to benefit immediately from better times when they come.

Dr. Dave Franzen
NDSU Extension Soil Specialist
dfranzen@ndsuext.nodak.edu


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