2. toseedingrate)atAberdeenandBeresfordlocations,SD,in2014and2015.

## Established plant population and percentage (%) established plants (relative

Table

two rows were harvested for yield data, while the outer two rows were buffers. For the 19 cm row spacing, soybean was planted in 16 rows that is 6.5 m long and trimmed back to 5.5 m at V3 stage. The eight center rows were harvested for yield data with eight buffer rows on either side. The data collected included the number

in the middle two rows for the 76 cm row spacing and eight rows for the 19 cm row

center rows (76 cm spacing) and eight center rows (19 cm spacing) with a smallplot combine (Massey Ferguson 8XP, Duluth, Georgia, USA). Seed subsamples from each plot were taken to determine moisture, protein, and oil content. Seed moisture was determined by weighing seed samples before drying at 60°C for 48 hours and reweighing the samples after drying to adjust seed moisture to 13% or

mittance (NIT) spectroscopy (Infratec 1229 Grain Analyzer, Foss Tecator AB). Weeds were managed with a preemergent herbicide application of

(2,2-dichloro-ethenyl)-2,2-dimethyl-cyclopropanecarboxylate] (Bayer

's protected LSD (0.05).

In 2014, the effects of row spacing on number of plants ha

S-metolachlor (Dual II) (Bayer CropScience, Research Triangle Park, NC) and two in-season application of glyphosate (PowerMax) (Monsanto Company, St. Louis, MO). The insecticide Baythroid [cyano(4-fluoro-3-phenoxyphenyl)methyl-3-

CropScience, Research Triangle Park, NC) was applied when soybean aphids (Aphis

Data were analyzed using PROC MIXED of SAS (SAS Research Institute, NC). Years and blocks were treated as random, and all other effects were considered

bined analysis revealed interactions between location and year, the data were split by year and then by location to analyze the significant interactions between row spacing, variety, and seeding rate within each location. Mean separation was

Average temperatures were slightly warmer at Beresford compared to Aberdeen, although in 2015, September was much warmer compared to 2014 at both locations (Table 1). Rainfall amounts and timing varied considerably for each location and each year. Aberdeen was drier (70.1 mm less rain) than long-term average in 2014 and wetter (28.1 mm more) than long-term average in 2015. Beresford was wetter than long-term average in both years with June 2014 receiving 132.1 mm more rain than average. The warmer and wetter conditions at Beresford in both years were conducive to overall better soybean growth and yield when

establishment (relative to seeding rate) were significant (<0.001) at both locations, while in 2015, row spacing effects were significant for the two traits (P = 0.02 and 0.01, respectively) only at Aberdeen (Table 2). Overall, plant establishment was greater in narrow rows compared with wide rows. On average, the difference in stand establishment between the two row spacings was greater at the Aberdeen location (10% points) compared to Beresford (6% points). Greater stand

's test was used to test for the homogeneity of variance. After com-

 1

<sup>1</sup> at the V4 growth stage determined by counting the number of plants

. Seed protein and seed oil were determined using a near-infrared trans-

. Seed yield was determined by harvesting two

<sup>1</sup> and percent stand

of plants ha

130 g kg

 1

fixed. Levene

performed using Fisher

3. Results and discussion

3.1 Climate and weather

compared to Aberdeen.

108

3.2 Established plant population

spacing and converting to plants ha

Soybean - Biomass, Yield and Productivity

glycines) reached economic thresholds.

establishment in narrow rows has been observed by others in the Upper Midwest [2, 16]. As expected increasing seeding rate increased the number of established plant ha<sup>1</sup> at both locations and in both years. Percent established plants relative to the target population, on the other hand, decreased significantly as the seeding rate increased, and this was true in three of the four location-years. The rate of decrease in percent established plants was variable among location-years ranging from a high 12% drop between the lowest and the highest seeding rates at Beresford in 2015 to the lowest drop of 6.1% at Aberdeen in 2015. The reason for this is not clear, but Bruns [30] also reported a decrease in percent established plants with increasing seeding rate. However, it is generally accepted that under optimal conditions, stand establishment is about 80% of the seeding rate [30, 31]. In this study we achieved 80% stand establishment for all seeding rates except for the highest seeding rate of 506,500 at Beresford in 2014 and 2015 and in Aberdeen in 2015.

The row spacing seeding rate interaction effects were significant at Aberdeen in both years (Tables 2 and 3). The interaction was due to the fact that the decrease in the number of established plants or percent stand establishment with increase in seeding rate was lower for the 19 cm row spacing when compared to the wider row spacing in both years (4.7% vs. 17.2% in 2014; 2.4% vs. 5.9% in 2015).

#### 3.3 Seed yield

Row spacing, seeding rate, and variety effects on seed yield were significant in both years at Aberdeen and in 2015 at Beresford (Tables 4 and 5). In 2014, only seeding rate significantly affected seed yield at Beresford. In all four location-years, the narrow row spacing of 19 cm outyielded the wider row spacing of 76 cm with the yield advantage ranging from 37 to 424 kg ha<sup>1</sup> or 0.8 to 10%. Our results agree with earlier finding by other researchers in the Upper Midwest [2–4]. The advantage of narrow rows in the Northern United States is attributed to a shorter growing season and related canopy development and light interception. Narrow rows speed the rate of canopy closure and hence increase light interception [11, 12]. Earlier canopy closure means less moisture loss through evapotranspiration and results in higher water-use efficiency [13]. However, it is important to note that the advantage of narrow rows can diminish under moisture stress. Soybean plants grown in


narrow rows can deplete soil water early in the growing season resulting in insuffi-

Seed yield, seed protein concentration, and seed oil concentration of soybean as influenced by row spacing,

506,500 seeds ha<sup>1</sup> yielded significantly higher than the other three seeding rates, while the three lower seeding rates of 247,000, 333,500 and 420,000 had similar yields at Aberdeen in 2014 and 2015 and at Beresford in 2015. Carpenter and Board [21], Cox et al. [32], and Thompson et al. [8] reported no yield response of soybean to seeding rate and attributed this to the fact that soybean compensates for space in the canopy by adding more branches. Similarly, Cox and Cherney [6] reported that soybean compensated with more biomass, pods, and seed plant<sup>1</sup> at lower seeding rates. On the other hand, other researchers have reported that increasing seeding rate can result in greater yield [22, 31]. While the present study supports the later research findings, it is important to note that the seed yield increase observed in this study due to seeding rate was very low ranging from 3 to 7%. This supports the reported [6] compensatory power of soybean plants at lower seeding rates.

Seeding rate effects for seed yield were significant for both years and locations

Row spacing seeding rate interaction for seed yield was significant only at one location-year (Beresford, 2015). The interaction was due to the fact that the narrow

cient available water during the reproduction stages of growth [14, 20].

Aberdeen Beresford

Seed oil (g kg<sup>1</sup> )

19 4189a\* 336.1 180.2 4765 347.9a 178.0 76 3765b 321.7 179.9 4728 344.3b 179.0

247,000 3863b 307.8b 180.9 4542c 343.5c 179.5a 333,500 3964b 333.2ab 180.2 4743b 344.4bc 179.2ab 420,000 3986ab 336.1a 179.6 4832ab 346.6b 178.1bc 506,500 4095a 336.4a 179.6 4868a 350.0a 177.4c

S <0.001 0.187 0.549 0.566 <0.001 0.121 SR 0.007 0.113 0.199 <0.001 <0.001 0.004 S SR 0.853 0.470 0.971 0.192 0.228 0.131 V <0.001 0.841 0.001 0.386 <0.001 0.258 V S 0.024 0.408 0.098 0.056 0.699 0.887 V SR 0.195 0.428 0.147 0.249 0.143 0.608 V S SR 0.823 0.461 0.777 0.639 0.705 0.393 \*Within each column and each treatment, means followed by the same letter are not significantly different (P 0.05). # Soybean varieties 0906R2 and 1108R2 were grown at Aberdeen and 2306R2 and 2408R2 at Beresford.

3888b 327.4 179.2b 4765 344.0b 178.8

4067a 329.3 180.9a 4727 348.2a 178.3

Yield (kg ha<sup>1</sup> ) Seed protein (g kg<sup>1</sup> )

Seed oil (g kg<sup>1</sup> )

Seed protein (g kg<sup>1</sup> )

Row spacing (S) (cm)

Variety (V)# 0906R2/ 2306R2

1108R2/ 2408R2

Table 4.

111

Seeding rate (SR) (seeds ha<sup>1</sup>

Yield (kg ha<sup>1</sup> )

DOI: http://dx.doi.org/10.5772/intechopen.80748

)

Row Spacing and Seeding Rate Effects on Soybean Seed Yield

Analysis of variance (P > F)

seeding rate, and variety at two locations in South Dakota in 2014.

(Tables 4 and 5). In all four location-years, the top seeding rate of

#### Table 3.

Interaction of row spacing and seeding rate for established plants ha<sup>1</sup> and percentage (%) stand establishment at Aberdeen, SD, in 2014 and 2015.


Row Spacing and Seeding Rate Effects on Soybean Seed Yield DOI: http://dx.doi.org/10.5772/intechopen.80748

\*Within each column and each treatment, means followed by the same letter are not significantly different (P 0.05). # Soybean varieties 0906R2 and 1108R2 were grown at Aberdeen and 2306R2 and 2408R2 at Beresford.

#### Table 4.

establishment in narrow rows has been observed by others in the Upper Midwest [2, 16]. As expected increasing seeding rate increased the number of established plant ha<sup>1</sup> at both locations and in both years. Percent established plants relative to the target population, on the other hand, decreased significantly as the seeding rate increased, and this was true in three of the four location-years. The rate of decrease in percent established plants was variable among location-years ranging from a high 12% drop between the lowest and the highest seeding rates at Beresford in 2015 to the lowest drop of 6.1% at Aberdeen in 2015. The reason for this is not clear, but Bruns [30] also reported a decrease in percent established plants with increasing seeding rate. However, it is generally accepted that under optimal conditions, stand establishment is about 80% of the seeding rate [30, 31]. In this study we achieved 80% stand establishment for all seeding rates except for the highest seeding rate of

The row spacing seeding rate interaction effects were significant at Aberdeen in both years (Tables 2 and 3). The interaction was due to the fact that the decrease in the number of established plants or percent stand establishment with increase in seeding rate was lower for the 19 cm row spacing when compared to the wider row

Row spacing, seeding rate, and variety effects on seed yield were significant in both years at Aberdeen and in 2015 at Beresford (Tables 4 and 5). In 2014, only seeding rate significantly affected seed yield at Beresford. In all four location-years, the narrow row spacing of 19 cm outyielded the wider row spacing of 76 cm with the yield advantage ranging from 37 to 424 kg ha<sup>1</sup> or 0.8 to 10%. Our results agree with earlier finding by other researchers in the Upper Midwest [2–4]. The advantage of narrow rows in the Northern United States is attributed to a shorter growing season and related canopy development and light interception. Narrow rows speed the rate of canopy closure and hence increase light interception [11, 12]. Earlier canopy closure means less moisture loss through evapotranspiration and results in higher water-use efficiency [13]. However, it is important to note that the advantage of narrow rows can diminish under moisture stress. Soybean plants grown in

2014 2015

333,500 323,209 96.9 288,825 86.6 420,000 397,359 94.6 362,975 86.4 506,500 484,963 95.7 429,052 84.7

333,500 252,786 75.8 265,055 79.4 420,000 293,908 69.9 327,694 77.9 506,500 354,304 69.9 367,908 72.6

Percentage (%) stand

Plant (ha<sup>1</sup> ) Percentage (%) stand

506,500 at Beresford in 2014 and 2015 and in Aberdeen in 2015.

Soybean - Biomass, Yield and Productivity

3.3 Seed yield

Row spacing (S) (cm)

Table 3.

110

at Aberdeen, SD, in 2014 and 2015.

Seeding rate (SR) (seeds ha<sup>1</sup>

)

Plant (ha<sup>1</sup> )

19 247,000 246,368 99.7 215,273 87.1

76 247,000 215,273 87.1 193,896 78.5

SE 3759 1.08 7306 1.9

Interaction of row spacing and seeding rate for established plants ha<sup>1</sup> and percentage (%) stand establishment

spacing in both years (4.7% vs. 17.2% in 2014; 2.4% vs. 5.9% in 2015).

Seed yield, seed protein concentration, and seed oil concentration of soybean as influenced by row spacing, seeding rate, and variety at two locations in South Dakota in 2014.

narrow rows can deplete soil water early in the growing season resulting in insufficient available water during the reproduction stages of growth [14, 20].

Seeding rate effects for seed yield were significant for both years and locations (Tables 4 and 5). In all four location-years, the top seeding rate of 506,500 seeds ha<sup>1</sup> yielded significantly higher than the other three seeding rates, while the three lower seeding rates of 247,000, 333,500 and 420,000 had similar yields at Aberdeen in 2014 and 2015 and at Beresford in 2015. Carpenter and Board [21], Cox et al. [32], and Thompson et al. [8] reported no yield response of soybean to seeding rate and attributed this to the fact that soybean compensates for space in the canopy by adding more branches. Similarly, Cox and Cherney [6] reported that soybean compensated with more biomass, pods, and seed plant<sup>1</sup> at lower seeding rates. On the other hand, other researchers have reported that increasing seeding rate can result in greater yield [22, 31]. While the present study supports the later research findings, it is important to note that the seed yield increase observed in this study due to seeding rate was very low ranging from 3 to 7%. This supports the reported [6] compensatory power of soybean plants at lower seeding rates.

Row spacing seeding rate interaction for seed yield was significant only at one location-year (Beresford, 2015). The interaction was due to the fact that the narrow


yield difference is attributable to season length and the longer duration variety maximizing yield due to extra growing days. This was supported by the fact that variety row spacing interaction effects on seed yield were significant only in one location-year (Aberdeen, 2014). Even then, the interaction was due to the longer duration variety (1108R2) yielding significantly higher than the shorter duration

rows. White mold, if present, would be a bigger problem under narrow rows due to high humidity under a dense canopy [4, 24]. The fact that the row spacing variety interaction was observed in only 1 year and under wider rows further confirms that

Variety seeding rate effects on seed yield were significant at both locations in 2015 (Table 5). The interactions are presented in Table 6. At Aberdeen the interaction was due to the fact that the longer duration variety showed an increase in seed yield with increasing seeding rate with the best yield obtained at a seeding rate

ent with the lowest seeding rate of 247,000 seeds ha<sup>1</sup> yield the same as the highest seed rate (Table 6). At Beresford, the variety row spacing interaction was, again, due to inconsistent performance of varieties at different seeding rates with the longer duration variety yielding highest at the lowest seeding rate. These results are not surprising as soybean plants respond to environmental conditions and can compensate for lower plant populations by producing more branches [32].

Row spacing, seeding rate, and variety effects for seed protein concentration were significant at Beresford in 2014 (Table 4). Seed from narrow rows had higher protein than from wider rows, while protein concentration increased with increasing seeding rate, and the longer duration soybean variety had higher seed protein

Yield (kg ha<sup>1</sup>

247,000 4103a\* 4034b 333,500 3985b 4099ab 420,000 3980b 4196a 506,500 4166a 4204a

247,00 4178b 4602a 333,500 4326a 4464b 420,000 4352a 4439b 506,500 4420a 4601a \*Within each column and year, means followed by the same letter are not significantly different (P 0.05).

Seed yield of soybean as influenced by seeding rate and variety at two locations in South Dakota in 2015.

)

Aberdeen (2015)

Beresford (2015) 2306R2 2408R2

) 0906R2 1108R2

. For the short duration variety, however, trends were differ-

the yield advantage of long duration varieties was related to season length.

) when seeded in 76 cm row spacings, but

) when seeded in 19 cm

variety (0906R2) (3906 vs. 3624 kg ha<sup>1</sup>

DOI: http://dx.doi.org/10.5772/intechopen.80748

3.4 Seed protein and seed oil concentration

of 506,500 seeds ha<sup>1</sup>

Seeding rate (seeds ha<sup>1</sup>

Table 6.

113

the two varieties yielding the same (4227 vs. 4151 kg ha<sup>1</sup>

Row Spacing and Seeding Rate Effects on Soybean Seed Yield

\*Within each column and each treatment, means followed by the same letter are not significantly different (P 0.05). # Soybean varieties 0906R2 and 1108R2 were grown at Aberdeen and 2306R2 and 2408R2 at Beresford.

#### Table 5.

Seed yield, seed protein concentration, and seed oil concentration of soybean as influenced by row spacing, seeding rate, and variety at two locations in South Dakota in 2015.

row spacing of 19 cm yielded significantly higher than the wider row spacing (76 cm) only at higher seeding rates of 420,000 (yield 5% higher) and 506,500 (yield 7% higher) (data not presented). Previous research results on row spacing seeding rate interactions are in dispute with some researchers [3, 6] reporting row spacing seeding rate interactions and soybean yielding greater at higher seeding rates and narrow row spacing as reported at Beresford in 2015. Other researchers have reported similar optimum seeding rates for both narrow and wider rows [8, 18, 19]. The current results are more in agreement with the later reports as 3 of 4 locationyears did not show significant row spacing seeding rate interaction.

Variety effects for seed yield were significant at Aberdeen in 2014 and 2015 and at Beresford in 2015. The varieties were chosen based on adaptation to the region but also were different in white mold ratings. At each location, the longer duration variety had a higher white mold rating (less resistant) than the shorter duration variety. In both years and in all instances, where varietal effects were significant, the longer duration variety was the higher yielding of the two. However, the difference was not considered to be related to white mold since white mold scouting showed little to no white mold infection in both years and locations. Instead, the

Row Spacing and Seeding Rate Effects on Soybean Seed Yield DOI: http://dx.doi.org/10.5772/intechopen.80748

yield difference is attributable to season length and the longer duration variety maximizing yield due to extra growing days. This was supported by the fact that variety row spacing interaction effects on seed yield were significant only in one location-year (Aberdeen, 2014). Even then, the interaction was due to the longer duration variety (1108R2) yielding significantly higher than the shorter duration variety (0906R2) (3906 vs. 3624 kg ha<sup>1</sup> ) when seeded in 76 cm row spacings, but the two varieties yielding the same (4227 vs. 4151 kg ha<sup>1</sup> ) when seeded in 19 cm rows. White mold, if present, would be a bigger problem under narrow rows due to high humidity under a dense canopy [4, 24]. The fact that the row spacing variety interaction was observed in only 1 year and under wider rows further confirms that the yield advantage of long duration varieties was related to season length.

Variety seeding rate effects on seed yield were significant at both locations in 2015 (Table 5). The interactions are presented in Table 6. At Aberdeen the interaction was due to the fact that the longer duration variety showed an increase in seed yield with increasing seeding rate with the best yield obtained at a seeding rate of 506,500 seeds ha<sup>1</sup> . For the short duration variety, however, trends were different with the lowest seeding rate of 247,000 seeds ha<sup>1</sup> yield the same as the highest seed rate (Table 6). At Beresford, the variety row spacing interaction was, again, due to inconsistent performance of varieties at different seeding rates with the longer duration variety yielding highest at the lowest seeding rate. These results are not surprising as soybean plants respond to environmental conditions and can compensate for lower plant populations by producing more branches [32].

## 3.4 Seed protein and seed oil concentration

Row spacing, seeding rate, and variety effects for seed protein concentration were significant at Beresford in 2014 (Table 4). Seed from narrow rows had higher protein than from wider rows, while protein concentration increased with increasing seeding rate, and the longer duration soybean variety had higher seed protein


#### Table 6.

row spacing of 19 cm yielded significantly higher than the wider row spacing (76 cm) only at higher seeding rates of 420,000 (yield 5% higher) and 506,500 (yield 7% higher) (data not presented). Previous research results on row spacing seeding rate

Seed yield, seed protein concentration, and seed oil concentration of soybean as influenced by row spacing,

ing seeding rate interactions and soybean yielding greater at higher seeding rates and narrow row spacing as reported at Beresford in 2015. Other researchers have reported similar optimum seeding rates for both narrow and wider rows [8, 18, 19]. The current results are more in agreement with the later reports as 3 of 4 location-

Variety effects for seed yield were significant at Aberdeen in 2014 and 2015 and at Beresford in 2015. The varieties were chosen based on adaptation to the region but also were different in white mold ratings. At each location, the longer duration variety had a higher white mold rating (less resistant) than the shorter duration variety. In both years and in all instances, where varietal effects were significant, the longer duration variety was the higher yielding of the two. However, the difference was not considered to be related to white mold since white mold scouting showed little to no white mold infection in both years and locations. Instead, the

interactions are in dispute with some researchers [3, 6] reporting row spac-

Aberdeen Beresford

Seed oil (g kg<sup>1</sup> )

19 4174a\* 325.8 195.3b 4521a 331.4a 195.0 76 4018b 326.7 198.7a 4325b 328.4b 195.8

247,000 4042b 323.2 197.7 4390b 329.4 195.4 333,500 4068b 328.3 196.8 4394b 330.1 195.8 420,000 4087b 325.4 197.1 4395b 329.8 195.5 506,500 4185a 326.2 196.6 4510a 330.3 194.9

S <0.001 0.956 0.041 0.003 0.021 0.372 SR 0.003 0.097 0.605 0.008 0.965 0.774 S SR 0.155 0.621 0.892 0.029 0.089 0.915 V 0.008 <0.001 0.839 <0.001 0.282 0.335 V S 0.895 0.018 0.160 0.269 0.069 0.771 V SR 0.004 0.675 0.008 <0.001 0.384 0.065 V S SR 0.038 0.682 0.221 0.487 0.948 0.154 \*Within each column and each treatment, means followed by the same letter are not significantly different (P 0.05). # Soybean varieties 0906R2 and 1108R2 were grown at Aberdeen and 2306R2 and 2408R2 at Beresford.

4058b 322.7b 197.1 4319b 328.1 195.7

4133a 328.8a 196.9 4526a 330.7 195.1

Yield (kg ha<sup>1</sup> ) Seed protein (g kg<sup>1</sup> )

Seed oil (g kg<sup>1</sup> )

Seed protein (g kg<sup>1</sup> )

Row spacing (S) (cm)

Variety (V)# 0906R2/ 2306R2

1108R2/ 2408R2

Table 5.

112

Seeding rate (SR) (seeds ha<sup>1</sup>

Yield (kg ha<sup>1</sup> )

Soybean - Biomass, Yield and Productivity

)

Analysis of variance (P > F)

seeding rate, and variety at two locations in South Dakota in 2015.

years did not show significant row spacing seeding rate interaction.

Seed yield of soybean as influenced by seeding rate and variety at two locations in South Dakota in 2015.

than the shorter duration variety. In 2015, variety row spacing effects were significant for protein at Aberdeen, while row spacing effects were significant at Beresford (Tables 4 and 5). The longer duration variety had higher seed protein at Aberdeen in 2015, while the narrow row spacing, again, had higher seed protein than the wider rows at Beresford in 2015. In 2014, variety effects were significant for seed oil concentration at Aberdeen, while seeding rate effects were significant at Beresford. The longer duration variety, 1108R2, had higher seed oil concentration than the shorter duration variety, 180.9 and 179.2 g kg<sup>1</sup> , respectively. At Beresford, seed oil concentration decreased with increasing seeding rate with the highest seeding rate of 506,500 seed ha<sup>1</sup> having 2.1 g kg<sup>1</sup> lower oil concentration than the lowest seeding rate. In 2015, row spacing and variety seeding rate effects for seed oil concentration were significant at Aberdeen (Table 5). The wider row spacing had significantly higher seed oil concentration than the narrow row spacing (198.7 vs. 195.3 g kg<sup>1</sup> ). There were no clear trends to explain the variety seeding rate interaction for seed oil concentration rather than that oil concentrations for both varieties were inconsistent from one seeding rate to the other. Research results on the effects of row spacing or seeding rate on protein content and seed oil concentration are not readily available. One consistent relationship, among studies, has been a negative correlation between seed protein and seed oil concentration. This negative correlation can be attributed to various genetic and environmental factors [33]. One possible explanation for the inconsistent relationship between row spacing and seeding rate and grain quality could be explained by water availability during seed filling. Rotundo and Westgate [34] found that water stress during seed filling (R5–R7) reduced protein and oil accumulation in soybean. Accounting for differences in water availability during seed filling and season could explain the major differences in research results for the row spacing and seeding rate studies. For example, longer duration varieties have prolonged seed maturation period resulting in greater oil or protein accumulation. Wider rows may preserve soil moisture making soil moisture conditions more favorable during the seed filling period and therefore greater oil concentration in the seed.

Acknowledgements

Author details

MN, USA

115

Matthew Schutte<sup>2</sup> and Thandiwe Nleya<sup>1</sup>

provided the original work is properly cited.

University, Brookings, SD, USA

\*

1 Agronomy, Horticulture, and Plant Science Department, South Dakota State

2 Business Development Representative, Bioverse Natural Solutions, Rushmore,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: thandiwe.nleya@sdstate.edu

The project was funded by the South Dakota Soybean Research and Promotion Council and South Dakota Agricultural Experiment Station. We thank Kevin Kirby,

Shawn Hawks, and Christopher Owusu for providing technical assistance.

Row Spacing and Seeding Rate Effects on Soybean Seed Yield

DOI: http://dx.doi.org/10.5772/intechopen.80748

## 4. Conclusions

A considerable number of growers in the Upper Midwest continue to grow soybean in wide row spacings (50–76 cm). Results from the present study and others indicate that soybean planted in narrow rows of 19 cm have higher yield potential when compared to soybean planted in wider rows. Soybean yield responded to seeding rate with maximum yield obtained at a seeding rate of 506,500 seeds ha<sup>1</sup> with no significant interaction between row spacing and seeding rate. In terms of soybean variety, the longer duration variety at each location had higher yield. Although the current results indicate that the best soybean yield can be obtained when the crop is seeded in row spacings of 19 cm at seeding rates of 506,500 seeds ha<sup>1</sup> , it must be noted that management choices for growers are influenced by a number of factors. In addition to yield potential, growers consider equipment costs associated with changing row spacings and disease and lodging problems associated with narrow rows or high seeding rates. And because of high costs of soybean seed, economic optimum seeding rates are usually less than seeding rates that result in highest yields. However, it is important that growers in the Upper Midwest consider seeding soybean in narrower rows as the current results and many others show that soybean planted with such row spacings have higher yield potential than soybean planted in wider rows.

## Acknowledgements

than the shorter duration variety. In 2015, variety row spacing effects were significant for protein at Aberdeen, while row spacing effects were significant at Beresford (Tables 4 and 5). The longer duration variety had higher seed protein at Aberdeen in 2015, while the narrow row spacing, again, had higher seed protein than the wider rows at Beresford in 2015. In 2014, variety effects were significant for seed oil concentration at Aberdeen, while seeding rate effects were significant at Beresford. The longer duration variety, 1108R2, had higher seed oil concentration

seed oil concentration decreased with increasing seeding rate with the highest seeding rate of 506,500 seed ha<sup>1</sup> having 2.1 g kg<sup>1</sup> lower oil concentration than the lowest seeding rate. In 2015, row spacing and variety seeding rate effects for seed oil concentration were significant at Aberdeen (Table 5). The wider row spacing had significantly higher seed oil concentration than the narrow row spacing (198.7

interaction for seed oil concentration rather than that oil concentrations for both varieties were inconsistent from one seeding rate to the other. Research results on the effects of row spacing or seeding rate on protein content and seed oil concentration are not readily available. One consistent relationship, among studies, has been a negative correlation between seed protein and seed oil concentration. This negative correlation can be attributed to various genetic and environmental factors [33]. One possible explanation for the inconsistent relationship between row spacing and seeding rate and grain quality could be explained by water availability during seed filling. Rotundo and Westgate [34] found that water stress during seed filling (R5–R7) reduced protein and oil accumulation in soybean. Accounting for differences in water availability during seed filling and season could explain the major differences in research results for the row spacing and seeding rate studies. For example, longer duration varieties have prolonged seed maturation period resulting in greater oil or protein accumulation. Wider rows may preserve soil moisture making soil moisture conditions more favorable during the seed filling

A considerable number of growers in the Upper Midwest continue to grow soybean in wide row spacings (50–76 cm). Results from the present study and others indicate that soybean planted in narrow rows of 19 cm have higher yield potential when compared to soybean planted in wider rows. Soybean yield responded to seeding rate with maximum yield obtained at a seeding rate of 506,500 seeds ha<sup>1</sup> with no significant interaction between row spacing and seeding rate. In terms of soybean variety, the longer duration variety at each location had higher yield. Although the current results indicate that the best soybean yield can be obtained when the crop is seeded in row spacings of 19 cm at seeding rates of

influenced by a number of factors. In addition to yield potential, growers consider equipment costs associated with changing row spacings and disease and lodging problems associated with narrow rows or high seeding rates. And because of high costs of soybean seed, economic optimum seeding rates are usually less than seeding rates that result in highest yields. However, it is important that growers in the Upper Midwest consider seeding soybean in narrower rows as the current results and many others show that soybean planted with such row spacings have higher

, it must be noted that management choices for growers are

). There were no clear trends to explain the variety seeding rate

, respectively. At Beresford,

than the shorter duration variety, 180.9 and 179.2 g kg<sup>1</sup>

Soybean - Biomass, Yield and Productivity

period and therefore greater oil concentration in the seed.

yield potential than soybean planted in wider rows.

vs. 195.3 g kg<sup>1</sup>

4. Conclusions

506,500 seeds ha<sup>1</sup>

114

The project was funded by the South Dakota Soybean Research and Promotion Council and South Dakota Agricultural Experiment Station. We thank Kevin Kirby, Shawn Hawks, and Christopher Owusu for providing technical assistance.

## Author details

Matthew Schutte<sup>2</sup> and Thandiwe Nleya<sup>1</sup> \*

1 Agronomy, Horticulture, and Plant Science Department, South Dakota State University, Brookings, SD, USA

2 Business Development Representative, Bioverse Natural Solutions, Rushmore, MN, USA

\*Address all correspondence to: thandiwe.nleya@sdstate.edu

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## References

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[2] De Bruin JL, Pedersen P. Effect of row spacing and seeding rate on soybean yield. Agronomy Journal. 2008; 100:704-710

[3] Cox WJ, Orlowski J, Ditommaso A, Knoblauch W. Planting soybean with a grain drill inconsistently increases yield and profit. Agronomy Journal. 2012;104: 1065-1073

[4] Lambert DM, Lowenberg-DeBoer J. Economic analysis of row spacing for corn and soybean. Agronomy Journal. 2003;95:564-573

[5] Pedersen P, Lauer JG. Corn and soybean response to rotation sequence, row spacing, and tillage system. Agronomy Journal. 2003;95:965-971

[6] Cox WJ, Cherney JH. Growth and yield responses of soybean to row spacing and seeding rates. Agronomy Journal. 2011;103:123-128. DOI: 10.2134/ agronj2010.0316

[7] Lee CD. Reducing row spacing to increase yield: Why it doesn't always work. Crop Management. St. Paul, MN: Plant Management Network; 2006. Available at: www. plantmanagementnetwork.org/cm/. DOI: 10.1094/CM-2006-0227-04-RV

[8] Thompson NM, Larson JA, Lambert DM, Roberts RK, Mengistu A, Bellaloui N, Walker ER. Mid-south soybean yield and net return as affected by plant population and row spacing. Agronomy Journal. 2015;107:979-989

[9] Burnside OC, Colville WL. Soybean and weed yields as affected by irrigation, row spacing, tillage, and Amiben. Weeds. 1964;12:109-112

[10] Dougherty CT. The influence of planting date, row-spacing, and herbicides on the yield of soybeans in Canterbury. New Zealand Journal of Agricultural Research. 1969;12:703-726 performance of indeterminate, semideterminate, and determinate soybean. Journal of Production Agriculture. 1991;4:391-395

DOI: 10.2134/agronj2004.1029

University; 2013

[19] Kratochvil RJ, Pearce JT, Harrison MR Jr. Row-spacing and seeding rate effects on glyphosate-resistant soybean for mid-Atlantic production systems. Agronomy Journal. 2004;96:1029-1038.

DOI: http://dx.doi.org/10.5772/intechopen.80748

Row Spacing and Seeding Rate Effects on Soybean Seed Yield

[27] USDA-NRCS. Web Soil Survey. Egan-Clarno-Chancellor complex. National Cooperative Soil Survey; 2017. http//:websoilsurvey.sc.egov.usda.gov/ App/WebSoilSurvey.aspx [Accessed: 25

[28] USDA-NRCS. Web Soil Survey.

Cooperative Soil Survey; 2017. http//: websoilsurvey.sc.egov.usda.gov/App/ WebSoilSurvey.aspx [Accessed: 25 July

[29] Channel Seeds. https//:www. channel.com/seedfinder/Pages/default.

[30] Bruns HA. Planting date, rate and twin-row vs. single-row soybean in the mid-south. Agronomy Journal. 2011;

[31] Heartherly LG. Early Soybean Production System (ESPS). In: Heartherly LG, Hodges HF, editors. Soybean Production in the mid-south. Boca Raton, FL: CRC Press; 1999.

[32] Cox WJ, Cherney JH, Shields E. Soybeans compensate at low seeding rates but not at high thinning rates. Agronomy Journal. 2010;102:1238-1243

Appearance and chemical-composition

[34] Rotundo JL, Westgate ME. Metaanalysis of environmental effects on soybean seed composition. Field Crops Research. 2009;110:147-156. DOI:

10.1016/j.fcr.2008.07.012

[33] Watanabe I, Nagasawa T.

of soybean seeds in germplasm collection of Japan. 2. Correlation among protein, lipid and carbohydrate percentage. Japanese Journal of Crop Science. 1990;59:661-666. DOI: 10.1626/

aspx [Accessed: 25 July 2018]

Great Bend-Beotia. National

July 2018]

2018]

103:1308-1313

pp. 103-118

jcs.59.661

[20] Ricks D, Christensen R, Carlson CG. Growing 100-bushel soybeans. In: Clay DE, Carlson CG, Clay SA, Wagner L, Deneke D, Hay C, editors. iGrow Soybean: Best Management Practices for Soybean Production. SDSU Extension, Brookings, SD: South Dakota State

[21] Carpenter AC, Board JE. Branch yield components controlling soybean yield stability across plant populations.

[22] Chen G, Wiatrak P. Seeding rate effects on soybean maturity group IV-VIII for the Southeastern production system: I. Vegetation indices. Agronomy

[23] Pennypacker BW, Risius ML. Environmental sensitivity of soybean cultivar response to Sclerotinia

sclerotiorum. Phytopathology. 1999;89:

[24] Crop Protection Network. White mold. Soybean Disease Management, CPN-1005; 2015. WhiteMold\_

[25] Hall R, Nasser LCB. Practice and precept in cultural management of bean diseases. Canadian Journal of Plant

[26] Buzzell RI, Welacky TW, Anderson TR. Soybean cultivar reaction and row width effect on Sclerotinia stem rot. Canadian Journal of Plant Science. 1993;

Pathology. 1996;18:176-185

Crop Science. 1997;37:885-891

Journal. 2011;103:32-37

CPN1005\_2015.Pdf

73:1169-1175

117

618-622

[11] Howe OW III, Oliver LR. Influence of soybean (Glycine max) row-spacing on pitted morning glory (Ipomoea lacunosa) interference. Weed Science. 1987;35:185-193

[12] Andrade FH, Calvino P, Cirilo A, Barbieri P. Yield responses to narrow rows depends on increased radiation interception. Agronomy Journal. 2002; 94:975-980

[13] Alessi J, Power JF. Influence of moisture, plant population, and nitrogen on dryland corn in the Northern Plains. Agronomy Journal. 1965;56:611-612

[14] Reicosky DC, Kaspar TC, Taylor HM. Diurnal relationship between evapotranspiration and leaf water potential of field-grown soybeans. Agronomy Journal. 1982;74:667-673

[15] Weber CR, Shibles RM, Byth DF. Effect of plant population and row spacing on soybean development and production. Agronomy Journal. 1966;58: 99-102

[16] Oplinger ES, Philbrook BD. Soybean planting date, row width, and seeding rate response in three tillage systems. Journal of Production Agriculture. 1992; 5:94-99

[17] Beurelein JE. Yield of indeterminate and determinate semidwarf soybeans for several planting dates, row spacings, and seeding rates. Journal of Production Agriculture. 1988;1:300-303

[18] Ablett GR, Beversdorf WD, Dirks VA. Row width and seeding rate

Row Spacing and Seeding Rate Effects on Soybean Seed Yield DOI: http://dx.doi.org/10.5772/intechopen.80748

performance of indeterminate, semideterminate, and determinate soybean. Journal of Production Agriculture. 1991;4:391-395

References

index.php.

100:704-710

1065-1073

2003;95:564-573

agronj2010.0316

2006. Available at: www.

Journal. 2015;107:979-989

116

and weed yields as affected by irrigation, row spacing, tillage, and Amiben. Weeds. 1964;12:109-112

[1] USDA-NASS, 2015. Crop Production Survey. https://www.nass.usda.gov/ Statistics\_by\_State/South\_Dakota/

Soybean - Biomass, Yield and Productivity

[10] Dougherty CT. The influence of planting date, row-spacing, and herbicides on the yield of soybeans in Canterbury. New Zealand Journal of Agricultural Research. 1969;12:703-726

[11] Howe OW III, Oliver LR. Influence of soybean (Glycine max) row-spacing on pitted morning glory (Ipomoea lacunosa) interference. Weed Science.

[12] Andrade FH, Calvino P, Cirilo A, Barbieri P. Yield responses to narrow rows depends on increased radiation interception. Agronomy Journal. 2002;

[13] Alessi J, Power JF. Influence of moisture, plant population, and nitrogen on dryland corn in the Northern Plains. Agronomy Journal.

[14] Reicosky DC, Kaspar TC, Taylor HM. Diurnal relationship between evapotranspiration and leaf water potential of field-grown soybeans. Agronomy Journal. 1982;74:667-673

[15] Weber CR, Shibles RM, Byth DF. Effect of plant population and row spacing on soybean development and production. Agronomy Journal. 1966;58:

[16] Oplinger ES, Philbrook BD. Soybean planting date, row width, and seeding rate response in three tillage systems. Journal of Production Agriculture. 1992;

[17] Beurelein JE. Yield of indeterminate and determinate semidwarf soybeans for several planting dates, row spacings, and seeding rates. Journal of Production

[18] Ablett GR, Beversdorf WD, Dirks VA. Row width and seeding rate

Agriculture. 1988;1:300-303

1987;35:185-193

94:975-980

1965;56:611-612

99-102

5:94-99

[2] De Bruin JL, Pedersen P. Effect of row spacing and seeding rate on

soybean yield. Agronomy Journal. 2008;

[3] Cox WJ, Orlowski J, Ditommaso A, Knoblauch W. Planting soybean with a grain drill inconsistently increases yield and profit. Agronomy Journal. 2012;104:

[4] Lambert DM, Lowenberg-DeBoer J. Economic analysis of row spacing for corn and soybean. Agronomy Journal.

[5] Pedersen P, Lauer JG. Corn and soybean response to rotation sequence, row spacing, and tillage system. Agronomy Journal. 2003;95:965-971

[6] Cox WJ, Cherney JH. Growth and yield responses of soybean to row spacing and seeding rates. Agronomy Journal. 2011;103:123-128. DOI: 10.2134/

[7] Lee CD. Reducing row spacing to increase yield: Why it doesn't always work. Crop Management. St. Paul, MN: Plant Management Network;

plantmanagementnetwork.org/cm/. DOI: 10.1094/CM-2006-0227-04-RV

[8] Thompson NM, Larson JA, Lambert DM, Roberts RK, Mengistu A, Bellaloui N, Walker ER. Mid-south soybean yield and net return as affected by plant population and row spacing. Agronomy

[9] Burnside OC, Colville WL. Soybean

[19] Kratochvil RJ, Pearce JT, Harrison MR Jr. Row-spacing and seeding rate effects on glyphosate-resistant soybean for mid-Atlantic production systems. Agronomy Journal. 2004;96:1029-1038. DOI: 10.2134/agronj2004.1029

[20] Ricks D, Christensen R, Carlson CG. Growing 100-bushel soybeans. In: Clay DE, Carlson CG, Clay SA, Wagner L, Deneke D, Hay C, editors. iGrow Soybean: Best Management Practices for Soybean Production. SDSU Extension, Brookings, SD: South Dakota State University; 2013

[21] Carpenter AC, Board JE. Branch yield components controlling soybean yield stability across plant populations. Crop Science. 1997;37:885-891

[22] Chen G, Wiatrak P. Seeding rate effects on soybean maturity group IV-VIII for the Southeastern production system: I. Vegetation indices. Agronomy Journal. 2011;103:32-37

[23] Pennypacker BW, Risius ML. Environmental sensitivity of soybean cultivar response to Sclerotinia sclerotiorum. Phytopathology. 1999;89: 618-622

[24] Crop Protection Network. White mold. Soybean Disease Management, CPN-1005; 2015. WhiteMold\_ CPN1005\_2015.Pdf

[25] Hall R, Nasser LCB. Practice and precept in cultural management of bean diseases. Canadian Journal of Plant Pathology. 1996;18:176-185

[26] Buzzell RI, Welacky TW, Anderson TR. Soybean cultivar reaction and row width effect on Sclerotinia stem rot. Canadian Journal of Plant Science. 1993; 73:1169-1175

[27] USDA-NRCS. Web Soil Survey. Egan-Clarno-Chancellor complex. National Cooperative Soil Survey; 2017. http//:websoilsurvey.sc.egov.usda.gov/ App/WebSoilSurvey.aspx [Accessed: 25 July 2018]

[28] USDA-NRCS. Web Soil Survey. Great Bend-Beotia. National Cooperative Soil Survey; 2017. http//: websoilsurvey.sc.egov.usda.gov/App/ WebSoilSurvey.aspx [Accessed: 25 July 2018]

[29] Channel Seeds. https//:www. channel.com/seedfinder/Pages/default. aspx [Accessed: 25 July 2018]

[30] Bruns HA. Planting date, rate and twin-row vs. single-row soybean in the mid-south. Agronomy Journal. 2011; 103:1308-1313

[31] Heartherly LG. Early Soybean Production System (ESPS). In: Heartherly LG, Hodges HF, editors. Soybean Production in the mid-south. Boca Raton, FL: CRC Press; 1999. pp. 103-118

[32] Cox WJ, Cherney JH, Shields E. Soybeans compensate at low seeding rates but not at high thinning rates. Agronomy Journal. 2010;102:1238-1243

[33] Watanabe I, Nagasawa T. Appearance and chemical-composition of soybean seeds in germplasm collection of Japan. 2. Correlation among protein, lipid and carbohydrate percentage. Japanese Journal of Crop Science. 1990;59:661-666. DOI: 10.1626/ jcs.59.661

[34] Rotundo JL, Westgate ME. Metaanalysis of environmental effects on soybean seed composition. Field Crops Research. 2009;110:147-156. DOI: 10.1016/j.fcr.2008.07.012

**119**

**Chapter 7**

**Abstract**

potential.

**1. Introduction**

Beneficial Plant Microbe

Resistance of Soybeans

*Alex Soupir and Heike Bücking*

endophytes, rhizobia, tripartite interactions

Interactions and Their Effect on

*Arjun Kafle, Kevin Garcia, Vincent Peta, Jaya Yakha,* 

Nutrient Uptake, Yield, and Stress

Plants are meta-organisms that are associated with complex microbiomes. Many

of the microorganisms that reside on plant surfaces (epiphytes) or within plant tissues (endophytes) do not cause any plant diseases but often contribute significantly to the nutrient supply of their host plant and can help the plant to overcome a variety of biotic or abiotic stresses. The yield potential of any plant depends not only on successful plant traits that improve, for example, the adaptation to low input conditions or other stressful environments but also on the plant microbiome and its potential to promote plant growth under these conditions. There is a growing interest to unravel the mechanisms underlying these beneficial plant microbe interactions because the activities of these microbial communities are of critical importance for plant growth under abiotic and biotic stresses and could lead to the development of novel strategies to improve yields and stress resistances of agronomically important crops. In this chapter, we summarize our current understanding of the beneficial interactions of soybean plants with arbuscular mycorrhizal fungi, nitrogen-fixing rhizobia, and fungal and bacterial endophytes and identify major knowledge gaps that need to be filled to use beneficial microbes to their full

**Keywords:** arbuscular mycorrhizal symbiosis, biological nitrogen fixation,

The plant rhizosphere and phyllosphere is colonized by a wide range of epiphytic and endophytic microorganisms, and these microorganisms can establish beneficial, neutral, or detrimental associations of varying intimacy with their host plant. Recent developments in sequencing technologies have enabled us to study the composition and function of plant microbiomes, but these microbiomes are dynamic and differ among different plant tissues and in response to the environment. The microbiome can also be seen as "the second plant genome" and can consist of 10 times more genes than typical plant genomes [1]. Beneficial microorganisms that

## **Chapter 7**
