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Starter fertilizer is a significant
cost in many corn producers' budgets. The addition of a starter is known to be
especially important during early, sometimes stressful planting conditions.
Typically, a 2x2 application of fertilizer high in phosphorous at planting
helps to jump start the corn during adverse conditions. A standard application
of MAP or 10-30-10 can cost anywhere from 10$-15$ per acre.
Pennsylvania has an abundance of fields
that are considered high in phosphorous, (over 50 ppm) mostly due to a history
of manure applications. At Penn State, I am currently studying starter
fertilizer alternatives for corn on soils with high phosphorous soil tests with
Drs.Doug Beegle and Greg Roth in the Department of Crop and Soil Sciences. In
this study, we're questioning whether or not it's necessary for a starter on
these high P soils at planting, or can our money be better spent on a nitrogen
fertilizer like ammonium sulfate?
In 2001, with the help of farmers and
cooperators, we collected data from 19 on-farm sites throughout the state, and
1 in New York. Soil P tests in 2001 sites ranged from 52 ppm to 191 ppm.We also
established three similar field experiments in Centre and Dauphin Counties. At
each of these high P sites, corn was planted using three starter fertilizer
treatments (no starter, 10-30-10, and ammonium sulfate). Plant samples were
collected for nutrient uptake analysis and dry matter yield when the corn was
between the V6 and V9 leaf stage. This was done to compare the impact of
starter fertilizers on early season growth. We also measured their influence on
moisture and grain yield on these high P soils.
Early Growth
In 2001 the early season growth
response to starter fertilizer was quite variable across all locations. We
found a significant increase in dry matter yield at the V6-V9 leaf stage at 11
of 22 locations when a starter was used. Averaged over all locations, the
10-30-10 treatment was 17% higher in dry matter when compared to the treatment
with no starter. The ammonium sulfate treatment also had a 23% increase over
the no starter treatment. These results confirmed to us what we have seen in
the past- despite high soil P levels you will often notice a growth response to
a starter fertilizer. We have also shown that you can get the same growth
response with a N based starter rather than one that contains P.
Grain Yield & Moisture
The grain yield response to starter
fertilizers was generally smaller and less frequent than the early growth
response. We found significant effects from a starter occurred at 5 locations,
each of them having a soil P test between 52 and 75 ppm. There were no
significant positive yield responses due to starter when the soil tested from
76 to 191 ppm. So far, our data seems to indicate a greater positive impact
from starter fertilizer when the soil test P levels are at the low end of the
high P range. Averaged overall sites we saw a 3.7% yield advantage due to using
a starter. We found a similar response using either the 10-30-10 or the
ammonium sulfate starter. From this we conclude that a) the starter yield
response is often small and b) the starter benefit can often be achieved with
an alternative like ammonium sulfate.
Averaged over all locations, there was
less than 1% difference in moisture between all treatments. Although a
significant treatment effect was found at four locations, no conclusions can be
drawn from this preliminary data. Generally starter fertilizers have resulted
in slightly lower grain moistures in other studies.
Starter Formulation Study
In 2001, a starter formulation trial
was conducted in conjunction with the Farm Operations staff at Penn State. A
field was selected that tested 56 ppm P and 142 ppm K, with a pH of 6.0 that
had been cropped to wheat in 2000. Corn was planted no-till on May 2 in plots
four rows wide and 700 feet long. Each treatment was replicated four times and
harvested with a commercial combine in mid November. The treatments were
designed to compare various dry blends of ammonium sulfate and P and K, as well
as several liquid pop-up fertilizers applied in the row with the seed at 3
gallons/acre.
Early Growth
Differences in early growth were subtle
and not statistically different, but there was a tendency for several
treatments to have greater early season dry matter accumulation than the check.
These included the pop-up treatments, the 10-30-10 and the 16-8-8. Conditions
for emergence and early season growth were good at this site.
Grain Yield
The grain yield response to the starter
fertilizers was mixed at this site. Most of the 2x2 fertilizers tended to have
lower yields than the check. We have observed this on several other occasions
where the crop is impacted with a midsummer drought, similar to what happened
here. This yield depression did not occur with the pop-up fertilizers, however.
The pop-up treatments yielded significantly higher than the 2x2 treatments by
about 10 bushels per acre and averaged about 4% higher yields than the check.
There were no differences among the pop-up fertilizer treatments.
These studies suggest a need for
further evaluation of pop-up fertilizers as well as other fertilizer
alternatives on high P soils. We plan to continue our research efforts in 2002
to refine our ability to make efficient recommendations of starter fertilizers
on high P soils. |
