February 2022 - 26

The Potato Association of America mission statement: The PAA and
its allied associations must strongly support the private sector through
Extension, research and commercialization efforts aimed at enhancing
the role of the potato as the premier food source for the 21st century.
Breeding red varieties that
require less nitrogen
By Thomas Stefaniak,
Laura Shannon
Potato Association of America
E
very grower reading this magazine
knows exactly what they spent
on nitrogen (N) fertilization in
their most recent growing season. They
also know what their crop yielded, and
what their " take home pay " was for that
season of hard work. Are these growers
asking themselves if they got the best
" bang for their N buck " ?
I am not sure, but I believe they should
be thinking about this, and that is why
Laura Shannon's potato breeding team
at the University of Minnesota has been
researching how their breeding lines
perform at different N application rates,
with the ultimate goal of releasing new
varieties that require less N. If growers
can plant potatoes that require less N,
then less N will unnecessarily be wasted.
We all know potatoes require a lot
of nitrogen relative to other crops. We
think that different red varieties have
different N requirements. It has been
estimated that fertilizer costs represent
14% of total production costs for
growing potatoes. If we consider $3,000
to be a reasonable number for total
production cost per acre, $420 of that
is for fertilizer, and much of the fertility
requirements are for N.
Small grains are often grown in
rotation with potatoes in the Upper
Midwest. Estimates for the percentage
of
production
costs
that
are
for
fertilizer for spring wheat are indeed
higher (around 16%). However, the total
production cost for wheat in the region
is about $260 per acre, 16% of that being
for fertilizer ($42).
26
Spudman.com
Figure 1. Tuber yield for eight clones in 2018 and seven in 2017 at
four nitrogen application rates.
N rate (lb/A):
2000 -
1500 -
1000 -
500 -
0 -
2018
45
90
120
180
2017
Genotype
As a researcher with little business
knowledge, I am always impressed with
the average potato grower's business
acumen. As a plant breeder, I feel that
reducing grower production costs is
equal in importance to increasing yield
as a breeding objective.
Research has shown that an acre of
tablestock red potatoes requires 160 ±10
lbs/acre of N. However, this amount is
only adequate as a total application rate if
no N is lost from the field. Substantial N
leaching is known to occur in the Upper
Midwest and potatoes contribute to this
loss. In fact, research in Minnesota has
shown that only about 33-56% of applied
N is taken up by the potato crop. Previous
research at the university has reported
that 85% of the N not taken up by a
potato crop is lost to the environment.
In an experiment published by the
Shannon team in January, we analyzed
total yield with eight red potato clones.
In Figure 1 we see tuber yield for eight
red potatoes grown in 2018 and seven
in 2019. For all the clones the lowest
rate resulted in the highest percentage
of the applied N actually being taken
up by the crop, and the highest N rate
resulted in the lowest percentage. How
did this affect yield?
In Figure 2 we see how those N
applied translated into plot yield. This
figure suggests the 180 lb/A N rate, never
Tuber Yield per Unit N applied
Chieftain -
Dark Red Norland -
MN1 -
MN2 -
MN3 -
ND1 -
Red LaSoda -
Red Norland -
Chieftain -
Dark Red Norland -
MN1 -
MN2 -
MN3 -
Red LaSoda -
Red Norland -
http://www.Spudman.com
February 2022

Table of Contents for the Digital Edition of February 2022
