Wide Row Soybeans - Are They a Good Option for Ontario Growers

The majority of soybeans in Ontario are seeded in narrow rows (7 - 15"). The main issue with wide rows (30") is they often yield less than narrow rows in our climate. Research by the University of Guelph in the late 90's showed they yield 3-5 bu/ac less than narrow rows. Yield on 15" rows were equivalent to 7.5" rows. However, it may be possible to overcome this yield lag by promoting early season vegetative growth through starter fertilize and other management strategies with newer varieties. When using wide rows it also becomes possible to fertilizer in a 2X2 band which is an effective way to increase yields in a low soil testing field. Another strategy that could reduce the yield drag is the application of foliar fungicides.. Tramping losses are reduced on wide rows, and fungicide efficacy may be improved due to better spray penetration. With the widespread adoption of auto steer systems, strip tillage could play an important role in helping growers overcome the challenge of lower yields with wide rows.

Why consider wide rows? Wide rows have a number of advantages, including the need for only one piece of planting equipment for corn and soybeans, lower seeding rates, less lodging, and reduced disease pressure. It may also be possible to establish a late season cover crop in wide rows. Wide row (30") soybeans typically have less white mould because of increased air movement, sun penetration, and lower plant populations.

Replicated field trials were established at Elora, Bornholm, Ridgetown and Winchester in 2015. Pioneer Seeds also evaluated wide rows across a number of locations in Eastern Ontario. The results varied depending on the test site.

Figure 1. Spring strip tillage in 30" rows.

Figure 1. Spring strip tillage in 30" rows.

At the Elora research station the yield lag associated with wide rows could be won back through strip tillage in 2015 (Table 1). Fertilizer and fungicides also increased yields. However, the narrow rows were also highly responsive to management at that site. Overall yields were excellent, which likely contributed to the performance of wide rows.

Table 1. Closing the Yield Gap (Elora 2015)

  Yield
Bu/ac
1) 15" no-till (170 000 seeds/ac)
58.8
2) 30" no-till (170 000 seeds/ac)
54.0
3) 30" no-till (120 000 seeds/ac)
52.6
4) 30" strip-till
58.6
5) 30" strip-till + P K (2X2)
62.7
6) 30" strip-till + foliar fungicide
65.0
7) 30" all practices
68.4
8) 15" all practices
66.4

Treatments 3-8 = 120 000 seeds/ac
2 replicates, P = 11 ppm, K = 82 ppm

The yield lag could not be closed completely through management at the Bornholm location (Table 2). The highest yields were achieved in narrow rows with long season varieties. DS04-D3 have a relative maturity (RM) of 0.4 while Titanium's are a 1.3 RM.

Table 2. Closing the Yield Gap (Bornholm 2015)

 

Yield

Bu/ac

1) 15" no-till (170 000 seeds/ac)
56.3
2) 15" no-till (120 000 seeds/ac)
55.8
3) 30" no-till (170 000 seeds/ac)
51.9
4) 30" no-till (120 000 seeds/ac)
48.1
5) 30" strip-till
50.4
6) 30" strip-till + P K (2x2)
54.3
7) 30" strip-till + fungicide
54.2
8) 30" all practices
54.0
9) 15" all practices
60.8
10) 15" no-till (variety P12T82R)
65.3
11) 30" strip-till (P12T82R)
54.8
12) 30" all practices (P12T82R)
59.1
13) 15" no-till (variety Apex)
67.1
14) 30" strip-till (Apex)
62.5
15) 30" all practices (Apex)
61.8
16) 15" no-till (variety RR2 Titanium)
69.3
17) 30" strip-till (RR2 Titanium)
61.4
18) 30" all practices (RR2 Titanium) 6
62.5

Treatments 1-7 = variety NK S04-D3,
Treatments 4-8,11,12,14,15,17,18 = 120 000 seeds/ac
3 replicates, P = 15 ppm, K = 119 ppm

At the Winchester location (Table 3) the yield gap of wide rows could be gained back for the most part through management. This site was conventionally tilled.

Table 3. Closing the Yield Gap (Winchester 2015)

  Yield
Bu/ac
1) 15" (170 000 seeds/ac) 68.7
68.7
2) 15" (120 000 seeds/ac) 70.4
70.4
3) 30" (120 000 seeds/ac) 65.7
65.7
4) 30" (170 000 seeds/ac) 64.8
64.8
5) 30" (120 000 seeds/ac) + 80 lbs/ac 11-52-0,3 gal 6-24-6 68.4
68.4
6) 30" + 50 lbs/ac N 66.0
66.0
7) 30" + foliar fungicide 67.5
67.5
8) 30" + foliar fungicide + foliar feeding 69.3
69.3
9) 30" all practices 67.6
67.6

4 replicates

The Pioneer Seeds study showed no yield deficit to wide rows in eastern Ontario in 2015. On average the 30" rows yielded 62.1 bu/ac while the 15" rows yielded 60.1 bu/ac. It should be noted that these fields were highly productive and had white mould. The sites in western Ontario did not have white mould.

On average, the yield lag associated with wide rows was relatively small in 2015 and depended on trial location and variety. Since 2015 was an excellent soybean year with many treatments yielding over 60 bu/ac, these trials will be repeated in 2016. When there was a yield lag in wide rows it could potentially be won back with various management strategies including strip tillage, fertilizer, or foliar fungicides at most of the sites but not all. There was no evidence that wide rows responded more to these inputs than narrow rows. Overall, with adequate heat units and in fields that grow tall, bushy soybeans there may not be a yield lag associated with wide rows if the correct variety is planted. Success with wide rows will depend on good fertility, early planting, and excellent weed control. Wide rows are a good management choice for growers that have consistent white mould pressure and high yield potential. They are not a good choice for fields with lower yield potential, limited heat units, or late planting.


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