
Daniel Kaiser, Nutrient Management Specialist
Jeff
Vetsch, Soil Scientist
We had a late start to the
season, and planting is later than usual. Should you use a starter fertilizer? The
answer to that question is that it depends. Some research has shown later
plantings will still benefit from starter due to decreasing time to silking.
Decreasing the rate applied may be an option to speed up planting if you are
questioning whether to keep using starter. There is no right or wrong answer
whether to use starter or not in your production system. If you do choose
starter here are five tips which may help you get the most out of your
investment.
1. Make your decision
Research does not overwhelmingly
support the widespread use of starter fertilizer across Minnesota. The most
noticeable benefit to starter is increased early growth. However, this effect
can be purely cosmetic and not provide any benefits for yield. The primary
benefit to in-furrow application is enhanced uptake of nutrients, like nitrogen
and phosphorus, that are in short supply early in the growing season. Reduced
tillage systems may have a greater benefit when using in-furrow starter due to
cooler and wetter soils.
2. Weigh your placement
options
Placement options can vary
based on which nutrients you want to apply. Immobile nutrients like phosphorus,
potassium, and micronutrients like zinc need to be placed near the roots for
maximum benefit. Nitrogen and sulfur are mobile and too much of these nutrients
applied near the seed can reduce germination. In continuous corn, we’ve seen
some benefit to nitrogen and sulfur banded on the soil surface to the side of
the seed row. This also can work for corn following soybean in poorly drained
soils. Too much of any starter can present risks for stand damage. One way to mitigate these issues is placement
away from the seed with at least one inch of soil between the seed and the
starter band.
3. Choose a source
There are many options to
choose from when selecting liquid fertilizer for use as a starter. Corn yield
is mostly impacted by nutrients in the shortest supply. Selecting a starter
which will apply the needed nutrients is critical. If you want to enhance early
growth, select a starter with a high P2O5 content that
can economically supply 10 lbs P2O5 per acre and apply it
in-furrow. This will increase growth, hasten dry down at the end of the growing
season and possibly increase yield. For high residue systems, you’ll likely
need nitrogen and sulfur combinations of 28 or 32% UAN with ammonium
thiosulfate banded on the soil surface.
4. Ortho- versus poly-phosphate
The argument between whether
to use a 100% ortho-phosphate starter versus a source with polyphosphate
revolves around whether to buy a higher-cost low salt product versus 10-34-0.
While it is true that plants will not take up polyphosphate, 10-34-0 contains
both ortho- and polyphosphate. It can take time for polyphosphate to convert to
orthophosphate but it should occur rapidly in most soils. There may be some
benefit to the higher-cost products if you need to supply potassium, but the
best bet is to compare products by calculating the cost of the products per
unit nutrient applied. A product like 10-34-0 is still a good option as it
contains a greater concentration of P2O5 than other
products.
5. Decide on rate
Rate options vary by placement and what nutrients are being applied. Calculators
will aid in selecting the right rate, but keep in-furrow starter fertilizer
rates as low as required to get the desired effect. Remember that the amount of
fertilizer placed on the seed will vary based on soil dryness. Placement in a
sub-surface band away from the seed or one or two inches to the side of the row
on the soil surface allow greater flexibility. When selecting the right rate
account for the nutrients in the starter. Those applications should be
considered supplemental to what you apply in manure or dry fertilizer sources.
With any fertilizer source
the answer boils down to whether you need the nutrients. Yes, starter can
potentially pay by reducing drying costs but that is not guaranteed. The best
way to evaluate the practice is to turn off the starter for a few passes. See
if starter pays, then adjust your practices to ensure you are getting the most
profit for your investment.
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Support for this project was provided in part by the Agricultural Fertilizer Research & Education Council (AFREC).
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