Narrow Row - One More
I wanted
to revisit the narrow row corn issue, not because we haven’t had
enough written or said about it in the last ten years, but because a recently
published study from Michigan State University emphasizes some important
points. This particular study is attractive since it comes from nearby
Michigan; it also included 11 test sites over two years (1998 and 1999),
with various hybrids, 3 row widths (30”, 22” and 15”) and
five plant populations ranging from 22,400 to 36,000 plants per acre.
The study, conducted by William Widdicombe and Kurt Thelen, points to
a consistent increase of 2% in yield for 22-inch rows over 30-inch rows,
and a 4% increase for 15-inch rows compared to 30-inch rows (see Table
1). This yield increase resulting from row widths is more than others
have reported, especially from the Northeast where it has been rare to
see consistent narrow-row response. However, it is a more modest yield
advantage than the 8% increase that was discussed through the early nineties
and served as incentive for some of the early adopters to switch to narrow
rows.
Of note in this research is the wide range of plant populations that were
used within each row width and the fact that there was no population by
row width interaction. That is, increased plant population boosted corn
yields in a similar fashion in both the wide and narrow rows. Interestingly,
Table 2 illustrates that yield increases resulting from increasing plant
density were similar in nature to the increases resulting from narrowing
row widths.
Hybrids used in this study were selected based on maturity and on particular
characteristics in ear type (flex, determinate, indeterminate), in leaf
orientation (erect, semi-upright, wide) and in plant height (short, medium,
tall). As in most studies, the hybrid selected had a significant impact
on the yield, but there were no particular hybrids that did better in
narrow rows. In other words, hybrids that yielded better in wide rows
also yielded better in narrow rows. There were differences in the way
hybrids responded to the various populations, however. The researchers
could not explain hybrid response to population by examining the aforementioned
characteristics (ear type, height, leaf angle).
| Table
1 Row width effect on grain yield when averaged across plant populations, hybrids, locations, and years. Each value is the average of 880 observations. |
|
|
Plant
population (plants/acre)
|
Yield
(bu/ac)
|
|
30
inches
|
177
|
|
22
inches
|
181
|
|
15
inches
|
184
|
|
Source:
W.D Widdicombe and K.D Thelen, Agronomy Journal 94:1020-1023 (2002)
|
|
So as you
ponder this most recent report, you may be considering a switch to narrow
rows. I generally have been of the opinion that it takes a system approach
to pay for the narrow row conversion. If the twenty-inch planter is also
going to do soybeans and edible beans, and do them better with less seed
cost, then perhaps you can pencil it out. However, if the planter, tire
and header conversions all need to come out of a 2–4 per cent increase
in corn yield, then I am not very excited about the idea. More to the
point from this data set is the fact that you first should be optimizing
your productivity based on plant population where the extra capital costs
are zero and the yield responses are similar to narrowing rows.
| Table
2 Plant population effect on grain yield when averaged across hybrids, row widths, locations, and years. Each value is the average of 880 observations. |
|
|
Plant
population (plants/acre)
|
Yield
(bu/ac)
|
|
22,400
|
168
|
|
26,000
|
177
|
|
29,200
|
181
|
|
32,400
|
184
|
|
36,000
|
186
|
|
Source:
W.D Widdicombe and K.D Thelen, Agronomy Journal 94:1020-1023 (2002)
|
|
Perhaps the changes to your corn planter for this winter should be an accurate acreage meter and an accurate variable rate seed drive. I am not suggesting a GPS-driven variable rate seeding system, just one that allows you the flexibility to adjust seeding rates with confidence from the tractor cab for a range of conditions. The following conditions may require more seeding rate adjustment than you have traditionally done: