ROW SPACING: IS IT AN ISSUE OR AN OPPORTUNITY?

Guy Lafondi, Byron Irvine2, George Clayton3, Douglas Derksen4, Eric Johnson5, Adrian Johnston6, David Rourke7.

1 Indian Head Research Farm, Indian Head, SK; 2 Saskatchewan Irrigation Development Cen Lacombe Research Station, Lacombe, AB; 4 Brandon Research Center, Brandon, MB; 5 Saskat and Food, Scott Research Farm, Scott, SK; 6 Melfort Research Farm, Melfort, SK; 7 AG-Qu

EXECUTIVE SUMMARY

The objective of this review was to summarize all known studies dealing wit spacing effects on various crops conducted in western Canada during the past 30 y An attempt was made to present as much data as possible in order to present data favouring both narrow and wide row spacings. The crops discussed were lentil, fie canary seed, oat, flax, durum, winter wheat, barley, spring wheat and canola with most information available for spring wheat and canola.

Although one could argue that for certain crops the risk of reduced yields row spacings in the range of 10-12" is frequent enough to cause concern, one has in mind what the absolute differences are and what the overall benefits are when considered on a whole farm basis. There were enough positive studies to show that absolute terms, high yields can be obtained with 12" spacings without compromising yield potential. If the yield potential is compromised, then in most cases it can explained on the basis of confounding effects due to seeding rates, experimental and methodology. In some cases fertilizer placement and availability resulted in against the wide row spacings. The discussion consisted of providing answers to frequently asked questions about row spacing.

In order to establish the full potential of wide row spacings, it is necessary evaluate this concept in the context of a zero tillage production system because utilize the benefits of standing stubble and the mulch effect of crop residues. R required comparing spacings under conventional and zero tillage production system These studies have not been done at the present time and until such a study is conducted of the true benefits of using wider row spacings will not be fully known.

1.0 INTRODUCTION

When we use the word issue, we usually associate it with a problem. In the context paper, we want to discuss how changes in row spacing can be a solution to the problem dealing with crop residues at the soil surface.

In order to understand the discussion about row spacing, you have to go back to eighties and remember all the excitement about European intensive cereal production tec which promoted concepts such as narrow row spacings, high seeding rates, high rates of fertilizer, split applications of nitrogen, plant growth regulators to control lodging to control plant diseases. However, from the mid-eighties to the early nineties, severe with heat and drought led to low yields and/or crop failures on the prairies. This resulted in urgency to develop crop production systems that would protect the soil from further degeneration and conserve more water. This culminated with the adoption of zero tillage, sometimes c low disturbance direct seeding systems and its adoption on a wide scale.

In the process of developing and promoting these new production systems, producer faced an important dilemma. Tall stubble for trapping snow can create problems for the operation because the rule of thumb is that the height of stubble should generally not spacing between the rows. However, the widely accepted view has been that narrow row spacings produce higher yields than wide row spacings. The producer was therefore left responsibility of seeking a balance between stubble height for conserving moisture and to maintain a narrow row spacing for maximizing grain yield.

This dilemma resulted in the need to evaluate the performance of wide spacings under zero tillage or low disturbance direct seeding systems. The question asked was whether yield penalty suffered from using 12" row spacings could be offset given the benefits in tall stubble for trapping snow, low soil disturbance, draft power requirements and cost purchasing new equipment, ease of seeding and whether changes could be made to avoid t yield penalty when using a 12" spacing.

The objective of this paper is to summarize all the research work that was done 0 spacing and on all crops with this type of information in Western Canada and to discus results in the context of a zero-tillage or low disturbance direct seeding system.

2.0 DISCUSSION OF RESULTS

2.1 Lentil

Two studies were found for lentil. In one study (Table 1) , the research was done conventional tillage using two varieties while the second study (Table 2) was direct se stubble using one variety. In the first study, no difference in two of the three years lower yields recorded in the third year but the yield levels were very low indicating 0 serious problems than row spacing limiting yield. Overall, no yield difference occurred 1500-2100 lbs/acre range. With Eston, yields on 12" spacing were clearly superior in on and inferior in the two other years. In the second study, no difference in yield between spacing even when using row spacings as wide as 16". In the second study, plant populated were monitored and populations tended to drop when the row spacings become wider. The d in plant populations could be due to damage from seed-placed fertilizer which could als the inoculation of the plants.

Based on the results presented, when good crop management is practised, it is possible to produce high yields of lentil, even when going to row spacing greater than 8 inches, in 12" and 16".Table 1: The effects of row spacing on grain yield (lbs/acre) in lentil at Morden, MB two different varieties.Table 2. The effects of row spacing on plant populations (#/m2) and grain yield (lbs/ac Lentil at Unity, SK.

Table 1. The effects of row spacing on grain yield (lbs/acre) in lentil at Morden, MB two different varieties
Row Spacing inches	1980	1981	1983	Average
	Laird
6	2089	1565	878	1510
9	1994	1668	681	1448
12	2103	1631	577	1436
	Eston
6	2739	2103	1578	2140
9	2715	2280	1335	2110
12	2318	2434	1240	1997
Taken from AliKahn and Kiehn, 1989. Can. J. Plant Sci. 69:377381.

Table 2. The effects of row spacing on plant populations (#/m2) and grain yield (lbs/acre) Lentil at Unity, SK
	1994		1995
Row Spacing inches	Plants/m2	Grain Yield	Plants/m2	Grain Yield
6	120	1476	175	600
8	108	1060	135	625
12	107	1263	125	590
16	86	1422	135	725
Taken from annual reports prepared by Eric Johnson for projects funded by the Farm Based Canada Saskatchewan Green Plan Agreement.

2.2 Field Pea

Only one study was found for row spacing effects on field pea using direct seeding 3).With one variety, there was no difference in yield among row spacings in the range inches. With the other variety, there was a decrease in yield going from 6-16" with a corresponding decrease in plant populations. It could be argued that the decrease in yield spacing increased could be due to the reduction in plant population. It should be noted producers have obtained very high field pea yields on 12" spacings without having to us spacings. The increase in concentration of seed-placed fertilizer at wide row spacings affecting not only plant populations but the vigour of the plants as a result of subtle to the root system and nitrogen fixation.

Further research is required under a wide range of conditions to determine the effect row spacing on field pea.Table 3. The effects of row spacing on plant populations (#/m2) and grain yield (bus/ac field pea at Unity, SK in 1994.

Table 3. The effects of row spacing on plant populations (#/m2) and grain yield (bus/ac) field pea at Unity SK in 1994.
	Green Pea (var. Radley)		Yellow Pea (var Express)
Row Spacing inches	Plants/m2	Grain Yield	Plants/m2	Grain Yield
6	64	21.3	71	52.9
8	74	23.8	83	51.0
12	70	19.4	64	46.1
16	50	24.8	52	35.8
Taken from annual reports prepared by Eric Johnson for projects funded by the Farm Based Canada Saskatchewan Green Plan Agreement.

2.3 Canary Seed

Only one study was found for this crop and there was no difference in yield between and 12" spacing (Table 4). The study was done using a conventional tillage system.Table 4. The effects of row spacing on grain yield of canaryseed at Indian Head, 5k. The results are based on three years of research.

Table 4. The effects of row spacing on grain yield of canaryseed at Indian head, Sk. The results are based on three years of research.
Row Spacing (inches)	Grain Yield (lbs/ac)
9	1433
12	1424
Taken from Holt, 1989. Can. J. Plant Sci.: 69:11931198.

2.4 Oat

Only one study with oat was found and there was no difference in yield between the and 12" spacing (Table 5). The study was conducted under a conventional tillage system.Table 5. The effects of row spacing on grain yield in oat in Saskatoon.

Table 5. The effects of row spacing on grain yield in oat in Saskatoon
Row Spacing (inches)	1966	1967
6	99.5	56.6
45	101.4	55.8
Taken from Austenson and Larter, 1969. Can. J. Plant Sci. 49:417420

2.5 Flax

A number of row spacing studies were reported over the period 1988-1995 (Table 6) Only one of eight studies showed a lower yield with 12" spacings with no differences be the other studies. The important point to note is that high yields of flax can be obtained row spacings and providing that adequate attention is given to fertilizer placement, ma economic yields in flax are possible with 12 inch row spacings. It should be noted that very susceptible to fertilizer damage and fertilizer should be placed away from the see minimize seedling damage. Flax is not a competitive crop and as such careful attention control is necessary at all times, and possibly more so if wide row spacing is combined soil disturbance.Table 6. The effects of row spacing on grain yields (bus/ac) of flax at four locations Western Canada.

Table 6. The effects of row spacing on grain yields (bus/ac) of flax at four locations in Western Canada.
	Indian Head			Ituna	Lethbridge			Melfort
Row Spacing inches	1989	1990	1991	1990	1993	1994	1995	Row Spacing inches	1988/1990
4	12	33	28	17				3.5	21
8	13	33	28	18	17	6	17	7.0	20
12	12	32	29	16	16	6	15	10.5	19
	From Lafond, 1993. Can. J. Plant Sci. 73: 375382. Zerotillage.				R. Blackshaw, pers. communication. Zero tillage			Stevenson and Wright, 1996. Can J. Plant Sci. 76:537544. Conventional tillage

2.6 Durum

Results from 3 separate studies conducted at three different locations and over a range of yields (12 to 76 bus/acre) showed that yields of durum were not affected by rows ranging from solid seeding to 12 inches. All studies were done under zero tillage.

< TD>41

Table 7. The effects of row spacing on grain yield (bus/ac) in durum at three locations
	Indian Head						Brandon		Outlook (irrigation)
Row Spacing inches	1989	1990	1991	1992	1993 1	1994 1	1993 1	1994 1	Row Spacing inches	Average (5 station years)
4	12	24	49	60	58	40	34	49	3	76.3
8	13	24	51	61	61	35	49	6	76.2
12	14	26	52	62	61	42	35	47	8	76.4
From Lafond, 1994. Can. J. Plant Sci. 74: 703711 and 1 Lafond (unpublished results).									Solid Seeding	76.0

2.7 Winter Wheat

Research trials looking at row spacing in winter wheat span the years 1985 to 199 During those years, conclusions of no row spacing effects on grain yield all the way to decrease in grain yield with row spacing have been reported (Tables 8, 9, 10 and 11). It difficult to conclude what is the best approach given that producers want to use practi give them the greatest probability of success for attaining the highest yield possible. difference was observed between 7" and 10" but then no difference between 10" and 11". important to note, that high yields of winter wheat were reported with wide row spacing at those high yield levels, using a narrow row spacing did not improve grain yields. A definitive conclusion cannot be made about the best row spacing to use, it is important sure that adequate plant populations are established and that damage as a result of see fertilizer be minimized. In the brown soil zone at Swift Current, no difference in row between 11" and 14", were reported, regardless of stubble and year except for one year yield was higher at 14" than 12" (Table 11).

Table 8. The effects of row spacing on grain yield (bus/ac) of winter wheat at Indian Head, Sk. The results are based on three years of research.
Row Spacing inches	1990	1991	1992	1993	1994	Average
4	48.5	43.1	77.9	35.2	42.0	49.3
8	48.2	44.3	77.3	38.4	45.2	50.7
12	48.1	41.5	78.1	41.1	43.4	50.5
Lafond, unpulished results, Indian Head, SK.

Table 9. The effects of row spacing on grain yield (bus/ac) of winter wheat at selected in Northeast , SK.
Row Spacing (")	Melfort(1)	Aylsham(1)
3.5	54.9	51.6
7.0	52.5	53.4
10.6	46.8	46.9
14.2	45.6	46.8
Taken from Brandt et al. 1987. Proceedings of the 1987 Soils and Crops Workshop, University of Saskatchewan, S'toon, SK.

15.4

Table 10. The effects of row spacing on grain yield (bus/ac) in winter wheat at selected locations in 5K.
	1985/861				1986/871
Row Spacing (")	Watrous	Carlyle	Clair	P.Plain	Watrous	Carlyle	Clair	S'toon
6	10.3	43.4	32.3	34.3	8 .9	30.5	33.8	17.9
12	8.3	46.2	32.6	29.3	8 .6	30.6	30.1	15.8
1 Averaged over 6 seeding rates ranging from 0.31.8 bus/ac.
	1985/862				1986/872
Row Spacing (")	Watrous	Carlyle	Clair	P.Plain	Watrous	Carlyle	Clair	S'toon
6	16.3	50.7	38.5	32.4	20.0	35.4	38.1	24.7
8	49.7	32.9	32.6	16.9	29.2	37.1	22.1
12	11.8	47.0	31.0	28.3	17.9	28.5	31.6	18.3
18	13.2	42.0	26.8	25.6	16.6	26.3	30.0	26.5
24	10.9	39.7	22.5	21.6	13.2	21.3	27.5	14.1
2 Seeding rate of 1.3 bus/ac. Taken from Hultgreen et al. 1988. Proceedings of the Soils and Crops Workshop, University of Saskatchewan, S'toon, Sk.

Table 11. The effects of row spacing on grain yields (bus/acre) of winter wheat in the soil zone at Swift Current when grown on spring wheat, winter wheat and chemical fallow stubble in different years.
Row Spacing (inches)	Winter wheat		Spring wheat (silt loam)			Chemical fallow			Spring wheat (fine sandy loam)
	86	88	86	87	88	86	87	88	86	87	88
11	28	8	23	21	13	25	41	12	18	18	4
14	28	8	25	20	12	27	38	13	18	16	5
Level of sign.	ns	ns	*	ns	ns	ns	ns	ns	ns	ns	ns
Taken from: McCleod et al. 1996. Can J. Plant Sci. 76:207214.

2.8 Barley

A large number of row spacing studies in barley were found and unlike winter wheat evidence was such that the greater majority most of the studies showed no effect on gra due to row spacing (Table 12, 13, 14). In this case, it is easy to conclude that with b yields can be obtained even when using row spacings as wide as 12". The range in yields reported are 16 to 124 bus/acre. A combined analysis of barley yields across years and resulted in no significant difference between row spacings ranging from 6-12". A drop i was only observed at 16" (Table 14). However, in situations where no herbicides are use would be the case for in organic production, barley yields were higher with higher seed and narrow spacings (Kirkland. 1993. J. Sust. Agric. 3:95-104).

Table 12. The effects of row spacing on grain yield (bus/ac) of barley at Indian Head, and Brandon, MB.
Row Spacing (inches)	Indian Head1 (zerotill)						Indian Head2 (summerfallow)			Brandon3 (zerotill)
	1989	1990	1991	1992	19933	19943	1993	1994	1995	1993	1994
4	16.4	91.8	61.9	124.2	88.0	64.8	115	85.5	73.4	57.4	74.9
8	18.3	90.3	61.2	124.3	90.4	65.3	120	86.9	71.3	60.1	80.0
12	20.6	95.5	60.7	124.4	90.9	62.4	115	86.3	73.1	60.2	77.4
1 Lafond, 1994. Can. J. Plant Sci: 74:703711 2 Lafond and Derksen, 1996. Can. J. Plant Sci. 76:791793 3 Lafond et al., 1996. Better Crops 4:2022.

Table 13. The effects of row spacing on grain yield in barley at Saskatoon.
Row Spacing (inches)	1966	1967
6	80.6	46.4
12	77.0	43.3
Taken from Austenson and Larter, 1969. Can. J. Plant Sci. 49:417420.

Table 14. The effects of row spacing on plant populations and grain yield in barley at Unity, Foam Lake and Naicam, in SIC.
	1994
Row Spacing (inches)	Plants/m2	Grain Yield (bus./ac re)	Plants/m2	Grain Yield (bus./ac re)	Plants/m2	Grain Yield (bus./ac re)
6	66	54.3	70	69.1	133	53.1
8	72	52.8	89	65.9	96	48.7
12	76	54.7	77	69.8	71	48.6
16	66	53.0	89	58.3	71	46.2
	1995
6	245	34.0	155	29.0	145	33
8	160	33.0	100	24.0	137	36
12	170	30.3	90	23.0	80	27
16	130	30.3	90	18.0	90	35
Taken from annual reports prepared by Eric Johnson for projects funded by the Farm Based Canada Saskatachewan Green Plan Agreement.

2.9 Spring wheat

By far the largest data set with respect to effects of row spacings on grain yield spring wheat. Some studies like those summarized in Table 15 show no difference due to spacing among 4, 8 and 12" over a yield range of 7 to 82 bus/acre involving many years locations.

Some studies showed a yield reduction from 6-9" but no differences between 6 and (Table 17). In some, yield differences are observed in certain years favouring narrow r but not in others, even though the yield levels are the same no difference (Table 16).

In one study, a shank spacing of 10 and 15" was used onto which different openers bolted (Table 18). The openers consisted of a narrow side-banding opener type, which p1 fertilizer to the side and below the seed. The paired-row opener puts the fertilizer in below two seed row spaced about 5" apart while the sweep opener spreads the seed and fe together over a 6-8" area at the same level. Under conventional tillage, no difference narrow and paired row with 10" and 15" shank spacing but a slight reduction for the swe opener with the 15" shank spacing. Under zero tillage, no difference between the narrow sweep opener even though they tended to be lower than the paired row opener. The author that problems with seed and fertilizer separation occurred with the narrow opener which explain the yield reduction. The loose soil condition under conventional tillage probab for better separation.

Although a very clear and precise statement to the effect that row spacing in the 4-12" has no effect on grain yield in spring wheat is not possible, we can nonetheless providing proper crop production practises are used with wide row spacings, a yield red should not occur. The practises to be careful with will be discussed in the last section paper.

Table 15. The effects of row spacing on grain yield (bus/ac) of spring wheat at Indian SIC and Brandon, MB.
	Indian Head1 (zerotill)						Indian Head2 (conventional till) (summerfallow)			Brandon3 (zerotill)
Row Spacing (inches)	1989	1990	1991	1992	19933	19943	1993	1994	1995	1993	1994
4	6.8	42.0	49.3	52.1	47.3	39.7	78.5	70.7	51.2	22.5	38.9
8	7.5	41.9	49.4	52.1	49.9	41.4	82.2	66.3	51.5	23.3	41.6
12	7.4	42.2	49.1	51.2	51.2	41.9	82.2	65.1	50.4	24.1	38.1
1 Lafond, 1994. Can. J. Plant Sci: 74:703711 2 Lafond and Derksen, 1996. Can J. Plant Sci. 76: 791793. 3 Lafond et al. 1996. Better Crops 4:2022.

Table 16. The effects of row spacing on grain yield (bus/ac) for spring wheat at differ locations in Saskatchewan.
	Scott (198586)1		Melfort1
Row Spacing (inches)	Plants/m2	Grain Yield	Grain Yield
4.5	171	60.2	74.8
9.0	136	54.4	61.5
18.0	107	45.8
1 Averaged over the varieties Neepawa and HY320
Row Spacing (inches)	Melfort (1986)1	Carrot River1 (1986)	Saskatoon1 (1986)
3.5	35.3	35.0	40.1
7.0	35.1	31.1	43.2
10.6	34.7	30.4	40.5
14.2	33.2	27.8	38.3
1 Averaged over the varieties Neepawa and HY320. Taken from Brandt et al. 1987. Proceedings of the 1987 Soils and Crops Workshop, University of Saskatchewan, S'toon, SK.

Table 17. The effects of row spacing on the yield of spring wheat grown in Alberta for Edmonton area.
Row Spacing	Grain Yield (bus/acre)	Plant Height (cm)	1000 Seed Weight (g)
6	37a1	99.4a1	35.5b1
9	31b	97.0ab	36.4ab
12	34ab	94.9b	38.0a
1 Values followed by the same letter are not significantly different at the 5% level. Taken from Briggs 1975. Can. J. Plant Sci. 55:363367. The values were averaged over three varieties, three seeding rates, two locations and two years.

Table 18. The effects of shank spacing and opener type on the yield of spring wheat (bus/acre) at Minto, MB using two different tillage systems over two years (1994-1995).
	Conventional Tillage
Opener Type	10"	15"
Narrow SideBand Opener	38	37
Paired Row	38	37
Sweep	37	34
	Zero Tillage
Narrow SideBand Opener	34	33
Paired Row	37	36
Sweep	34	32
Xie, H.D. Rourke, A. Hargrave, 1996. Conservation Tillage Productivity Centre, Minto, MB. Annual Report.

Table 19. The effects of row spacing on the yield of spring wheat (bus/acre) at Melfort Brandon and Beaverlodge in 1996.
Row Spacing	Melfort	Brandon	Beaverlodge
9"	53.4	51.3	25.2
12"	52.5	50.3	28.9
Source	Johnston, Melfort Exp. Farm	Derksen, Brandon REs. Ctr.	Clayton, Lacombe Research Stn.

2.10 Canola

There are a significant number of papers dealing with the effect of row spacing 0 but for this discussion we restricted ourselves to discussing information developed in Canada. It is generally accepted that higher seeding rates and narrow row spacings resulting in greater weed competition. However, these conditions can result in greater lodging pote higher incidences of crop diseases. Since direct seeding openers are expensive and wid openers clear trash better, it would be a great advantage if row spacings of at least 1 used without having to experience decreases in yield.

Higher seeding rates and narrower row spacings have generally not improved Western Canadian canola yields greatly (Table 1). When the same amount of seed is planted in rows a greater number of plants establish and survive. This results in the more rapid development of the crop canopy. The development of a large canopy will improve the crop competitive ability with weeds. It is my opinion that a uniform stand which emerges qui more important than row spacing in the normal 6-12" range of row spacings. While a narrow spacing (more openers) will place seed in contact with a greater volume of soil and improve the uniformity of plant emergence this is also possible using superior openers of placing seed shallow on a moist and firm seed-bed even on wider rows. When good see soil contact allows rapid and uniform plant emergence, the value of narrow row spacings reduced providing weeds are adequately controlled.

Under direct seeding conditions, the residue from the previous crop will slow evaporation from the soil surface and thus may mitigate the effect of wider row spacing centre pivot irrigation, where this work was done, evaporation from the soil surface is importance since water is applied at 3-4 day intervals.

Early work was done by hand seeding and since no mention is made of weed control, assume hand weeding was done. Hand weeding would tend to favour narrow row spacings 5 hand weeding can not be done until the crop is well established, by which time significant competition may have occurred. Hand seeding may result in differential packing due to differing number of times the operator walked over the field. While some studies report reductions using current management practices on fallow these results differ from those by the Canola Council under direct seeding conditions andunder irrigated cropping conditions (moisture not limiting)

Table 20. The effect of row spacing on Brassica napus yields in Western Canada.
Site	# of years	previous crop/till	% of 6" spacing
			34"	89"	12"	1618"
Scott1	4	fallow	118		92
Winnipeg	3	fallow			81
Unity	3	stubble		107	98	100
Foam Lake	3	stubble direct		93	92	85
Naicam	3	stubble direct		97	95	84
Outlook small plot	3	irrigation	89		97	97
Outlook large plot	6	irrigation	101	104
Beaverlodge	2	fallow	144	93
Edmonton2	4	fallow		82	72	57
1 % of 8"; 2 Variable plot width and therefore questionable data in my opinion.

2.10.1 Studies Showing Reduced Yields at Wider Row Spacings.

Effect of row spacing and rates of seeding on response of canola to rates and placement of phosphate fertilizer.

Site Dark Brown Scott Loam and Dark Brown Sutherland Clay conventional tillage and weed control using herbicides.

Plot Size 6 x 19 fSeeding Equipment Double disc press

Fertilization Phosphorous was seed placed at 0 and 22 lbs P205 /ac

Seeding rates 2.7, 5.3, 8 lb/ac Previous Cron Fallow

Seed placed phosphorous fertilizer reduced plant numbers to a greater extent at the wid spacings. In this study 12" spacings produced 8% less seed with or without fertilizer difference between the 8 and 12 inch spacings was less than between the 4 and 8 inch sp There was no effect of seeding rate on yield although higher seeding rates increased p1 population (Table 21).

Table 21. Influence of row spacing on canola plant populations, grain yields and seed quality at Scott and Saskatoon 1985-1989.
Row Spacing inches	Plants/m2 2 year mean	Grain yield bu/zc 4 year mean	Protein % 3 year mean	P % 3 year mean	Oil % 2 year mean
4	112	46.8	27.0	.57	41.8
8	67	39.6	27.1	.57	41.9
12	45	36.5	26.9	.57	42.2
LSD (0.05)	11	1.7	.19	ns	.24
Ukrainetz, H. 1990. 198589. Final Report to the Canola Council of Canada Agronomic Research Program Grow with Canola.

Row spacing and seeding rates on canola in southern Manitoba.

Site Riverdale silty loam and Red River clay (Winnipeg, Manitoba)

Plot Size 16 rows 18Ì loSeeding Equipment Double disc press

Fertilization 34 lb/ac N as ammonium nitrate and 13 lb/ac elemental sulfur broadcast a

incorporated in the fall prior to planting. Seeding rates 1.3, 2.7, 5.3 and 10.7 lb/ac

Previous Crop (not specified in report)

Yields were measured on a 16.4 long section of 2 rows with one guard row on each of the yield test being removed just prior to harvest. In this trial, 12" rows gave 19% than rows spaced 6" apart. All seeding rates greater than 1.3 lb/ac had similar yields narrower row spacings had greater leaf area throughout the season and the higher seeding gave greater leaf area early in the season. The greater weed competition from narrow r high seeding rates is due in large part to the more rate development of canopy. It has reported that some of the hybrid canola cultivars have the genetic potential to rapidly large crop canopy (Table 22).

Table 22. Effect of row spacing on plant numbers and yield of rapeseed in Manitoba 198
Row Spacing (inches)	plant numbers/m2			yield (bu/ac)
	loam 1985	loam 1986	clay 1986	loam 1985	loam 1986	clay 1986
6	102 (75)	193 (75)	63 (34)	62.6	53.9	42.2
12	91 (55)	166 (69)	57 (32)	53.0	44.2	33.5
	ns	ns	ns	7.1	6.8	6.1
1 numbers in brackets are % of seeds planted. Morrison M.J. McVetty, P.B.E. and Scarth, R. 1990. Can. J. Plant Sci. 70:12737.

Effect of row spacing and seeding rate on canola yield in north west Alberta.

Site Beaverlodge

Plot Size 3' x 10' with varying number of Seeding Equipment Double disc hand seeder. The centre 1.5' x 8' area was harvested.

Fertilization 100 lb/ac N as ammonium nitrate and 45 lb/ac P205 broadcast and incorporated prior to planting. Seeding rates 6.2 and 12.4 lb/ac Previous Crop (not mentioned in r

The extremely high yields resulting from the 3 inch row spacing are difficult to unless weed competition was high early in the season. Wider row spacings were not test is interesting to note that yield differences between 6" and 9" spacings were very small the difference between 3 and 6 inch row spacings (Table 23).

Table 23. Effect of row spacing on plant numbers and yield of rapeseed in Northwest Alberta 1982-83.
Row Spacing (inches)	Plant numbers/m2		Yield (bu/ac)
	1982	1983	1982	1983
3	121	140	29.3	61.3
6	151	83	18.3	48.1
9	110	75	15.8	48.0
Christensen J.V. and Drabble J.C. 1984. Can. J. Plant Sci. 64: 101113.

Effects of row spacing and seeding rate on canola yields in Central Alberta.

The varying plot width may have contributed to the high yields at the 6" spacing to wider row spacings. It is interesting to note that the largest differences are between with fewer differences between 9 and 12" (Table 24).

Table 24. Effect of row spacing on the yield of rapeseed near Edmonton 1971-72.
Row Spacing (inches)	Yield (bu/ac)
	Brassica rapa				Brassica napus
	Parkland		Ellerslie		Parkland		Ellerslie
	1971	1972	1971	1972	1972	1972	1971	1972
6	48.8	47.9	37.1	45.6	55.9	61.4	42.4	53.2
9	42.4	42.5	28.5	40.1	35.4	55.1	35.4	47.9
12	41.5	41.1	30.2	36.8	32.1	47.7	35.8	38.6
24	31.7	25.8	26.4	33.8	24.6	37.4	24.8	34.8
Kondra, Z.P. 1975. Can. J. Plant. Sci. 58:549550.

2.10.2 Studies Showing no Yield Differences at Wider Row Spacings.

PAHI, 1995. Row Spacing trials 1993-95, Canola Production Centre Annual Reports

Site Unity, Naicam and Foam Lake.

Plot Size 30' x 400' with 20 harvested froSeeding Equipment Direct seed

with hoe openers Fertilization P, K and S seed placed as per soil test Nitrogen broadcast

70 lb/ac of N as urea Seeding rates 6 lb/ac Previous Crop cereal grain

The effect of row spacing was limited up to 12" but the 16" spacings were lower yielding but 2 of the 9 site years (Table 25). When this work was conducted, only grass weed c was possible with post emergence products and weed control was a problem in some tests higher infestations at wider row spacings. In 1994 both the Unity and Naicam sites ha volunteer barley which reduced plant stands at wider row spacings and weeds were a more serious problem at wider row spacings in Unity.

Table 25. Effect of row spacing on canola under direct seeded conditions 1993-95.
Row Spacing (inches)	Yield (bu/ac)
	Foam Lake			Naicam			Unity
	1993	1994	1995	1993	1994	1995	1993	1994	1995
6	24.0	28.1	28.6	15.4	28.4	28.0	41.0	33.5	14.1
12	21.6	25.7	28.1	15.1	27.0	27.2	41.1	34.3	16.5
12	24.0	23.0	27.3	14.7	26.2	27.4	40.7	33.1	13.5
16	22.0	21.8	24.9	11.4	24.4	25.8	40.9	30.7	15.3
PAMI, 1995. Row Spacing trials 199395, Canola Production Centre Annual Reports.

Canola production under irrigation (row spacing, seeding rates and fungicide application).

Site Outlook under centre pivot irrigation Plot Size 16' x 65', centrSeeding Equipment

Fertilization 100 lb/ac nitrogen was broadcast and incorporated or banded and 40 lb/ac

deep banded prior to seeding

Seeding rates 80, 150 and 220 seeds/m2 (approx 3,6 and 9 lb/ac) Previous Crop Wheat

With the exception of 1990 when plant stands were slow to establish due to an ext packing operation done on the broadcast seeded plots, yields were not affected by the seeding. Narrow rows and higher plant numbers had more plants but this did not influence grain yield Table 26). When sclerotinia infections occurred they were higher where the lodged more; generally this was with narrow rows and high seeding rates.

Table 26. Effect of seeding method on canola yields under irrigation 1990-92
Row Spacing (inches)	Yield (bu/ac)
	Outlook 1989	Outlook 1990	Riverhurst 1991	Outlook 1991	Outlook 1992	Riverhurst 1992
	346.8	43.9	42.0	29.1	48.2	33.3
6.5	43.9	46.6	41.5	29.1	49.2	30.8
8	53.6	43.7	43.5	23.3	54.9	33.5
Solid seed with sweeps	48.3	45.0	44.1	29.2	50.4	30.4
broadcast	39.6	42.8	42.3	29.2	52.3	32.0
Irvine, B. 1992. Saskatchewan Irrigation Development Centre Annual Report.

Effect of row spacing and seeding rate on canola grain yields and Sclerotinia infections.

Site Outlook under centre pivot irrigation

Plot Size 10' x 30' with varying number of row depending on row spacing. Approximately outside 2' on each side of the plot was removed prior to swathing

Seeding Equipment Amazone narrow row drill was used for all plots Fertilization 100 lb/ac nitrogen was broadcast and incorporated or banded and 40 lb/ac deep banded prior to seeding

Seeding rates 2.7 lb/ac Previous Crop wheat

Higher seeding rates increased lodging and Sclerotinia infection levels but row 5 had very little impact (Table 27). Thus while high plant populations may suppress weed increase in lodging under high moisture conditions results in harvest problems and potential reductions due to increased lodging and Sclerotinia levels. With the exception of the spacing, grain yields were not affected by row spacing.

Table 27. Effect of row spacing on lodging sclerotinia and yield under centre pivot irrigation.
Row Spacing (inches)	Lodging cm from soil		Sclerotinia % infection			Yield (bus/ac)
	1992	1993	1991	1992	1993	1991	1992	1993
3.2	75	115	1.5	13.3	6.0	26.2	52.7	36.0
6.3	69	112	5.0	11.5	4.7	30.5	56.2	41.7
12.5	77	117	2.7	15.3	11.7	28.8	56.3	39.7
18.8	73	121	3.8	13.5	7.0	27.6	54.5	43.6
25.2	80	126	2.0	12.8	11	20.4	59.4	34.9
9" band 19" space	72	109	2.2	10.3	3.0	25.1	57.2	41.7
LSD	12	11	ns	ns	ns	5.5	7.8	4.6
Irvine, B. and D. Duncan. 1993. Saskatchewan Irrigation Development Centre Annual Report.

Effect of row spacing on the yield of canola at selected sites in the Parkland soil zone

Site Melfort, Sk, Brandon, MB, Beaverlodge, AB.

Plot Size 24' x 60' with varying number of row depending on row spacing.

Seeding Equipment: Conserva-Pak plot seeder on 9" and 12" spacing

Fertilization 70 lbs/ac nitrogen was side-banded with phosphorus and sulfur.

Seeding rates 6 lbs/ac Previous Crop wheat

When the fertilizer is placed in such a manner as not to bias against any row spa and providing that no damage from side-banding will be incurred, then no yield difference should be expected as shown in Table 28. At both locations, the canola yields were not between 9 and 12 inches.

Table 28. The effects of row spacing on the yield of canola (bus/acre) at Melfort, Bra and Beaverlodge in 1996.
Row Spacing	Malfort	Brandon	Beaverlodge
9"	40.0	31.6	7.8
12"	43.1	31.3	8.9
Source	Johnston, Melfort Exp. Farm	Derksen, Brandon Res. Ctr.	Clayton, Lacombe Res. Stn.

Effect of shank spacing and opener type on the yield of canola at Minto, MB.

Site Minto, MB.

Plot Size 10' x 23' with varying number of row depending on row spacing.

Previous Crop wheat

It is very obvious from the data presented in Table 29, that going from of a shan of 10" to 15" did not have a negative effect on grain yield in canola regardless of the system or opener type used. In fact, there was a slight improvement with the 15" shank under zero tillage with all the opener types used. The paired row system tended to do b the narrow or the sweep opener. However some problems of poor seed and fertilizer separ was encountered with the narrow opener which would have biased the results downward emphasizing the importance of proper fertilizer separation to minimize damage to the em and growing crop.

Table 29. The effects of shank spacing and opener type on the yield of canola (bus/acre Minto, MB using two different tillage systems over two years (1994-1995).
	Conventional Tillage
Opener Type	10"	15"
Narrow SideBand Opener	27	27
Paired Row	30	30
Sweep	28	29
	Zero Tillage
Narrow SideBand Opener	33	35
Paired Row	36	39
Sweep	32	35

3.0 IMPLICATIONS OF RESULTS.

3.1 What are some of the advantages with the use of wide row spacings under zero-tillage?

• zero tillage has to do with the challenge of seeding through very heavy residue conditions, especially when combined with wet soil conditions i.e. less soil and r disturbance
• prairies, producers are encouraged to maintain tall stubble to trap more snow and increase soil moisture levels. However, the rule of thumb is that stubble height similar to row spacing. This means that by going to wider row spacing, we can or taller stubble and trap more snow. It is also well known that stubble cut at 10-1 reduce wind speed at the soil surface by 60% relative to a tilled surface. This b very critical in the drier parts of the prairies.
• Equipment Consideration: Adopting wider row spacings reduces the costs and the dr requirements because of the fewer number of openers present on the tool bar. However the are far reaching. For example, a 33' seeder with 9" spacing has 44 openers. B to 12" spacing, you have effectively increased the width of the machine to 44' for the same horsepower. This means that you have reduced your seeding time and tractor h by roughly 33%. This is important because it allows for greater timeliness in the operation, especially if the weather has not been cooperating. One could therefor that changes in row spacing can actually improve the timeliness of your seeding 0 and lower your long term machinery costs at the same time.

3.2 Can wider rows be used successfully with a conventional tillage system?

• til1age system (refer to Table 12, 15, 18 and 29) for barley, spring wheat and c those studies, the response did not change with tillage system. This means that a arguments used previously (refer to 3.1) with respect to equipment consideration applies for the conventional tillage system. The only important consideration would the implication for weed management.

3.3 Are weeds an important concern when using wide row spacings?

No studies in the past have tried to quantify the impact of row spacing on weeds, it pertains to weed communities, densities or control. One study is currently under Brandon in MB, at Melfort in SK and at Beaverlodge in AB where the effects of row spacing and fertilizer management on weed communities and densities are being quantified. It is too early at this time to make a recommendation. Problems with wide rows have been reported in the past. At this point, we can postulate that hi of soil disturbance will encourage weed growth relative to low soil disturbance. means that in a zero tillage systems, wide row spacings combined with narrow open will reduce weed growth because of less soil disturbance. We can therefore speculate weed problems will likely not change with the use of wider row spacings. There are numerous producers seeding on wide row spacings at the present time and if weeds such a problem with wide row spacings, it would have been noted, but it is not the missing in original

3.4 Are adjustments in seeding rates required when changing row spacing?

Most of the studies reported in section 2.0 of this paper were done at different rates and no statistical interactions between row spacing and seeding rate were r This is a clear indication that no changes in seeding rates are required when row changes are made.

3.5. Are changes in harvest management required?

An important concern expressed by producers with regards to the use of wide row spacings has to do with harvest management If your operation is set up with aerat and a grain dryer and straight combining is a normal part of your harvesting oper adjustments are required when changing to wide row spacings. However, if your harvest operation revolves around swathing, then switching to wide row spacings will require some adjustments. It will not be a problem for crops like field pea, lentil, canola becomes an important concern with cereals, especially if the crop is thin. Some p ways to minimize problems is to swath at a different angle to the direction of se This can easily be done with a self-propelled swather. With a pull-type swather, have to seed at an angle. Producers who use wide row spacings and regularly swath crops have made the observation that with moderate to heavy cereal crops, it is n concern, even if when swathing in the same direction as the seeding operation.

3.6 Does row spacing have an effect on plant diseases?

Work at the Saskatchewan Irrigation Development Centre in Outlook, SK on canola showed that row spacing had very little influence on sclerotinia infection levels work on wheat and barley at Indian Head and Brandon showed that root diseases act decreased at the wide row spacings. Work at Minto on wheat showed that at high le the increase in grain yield using narrow rows was only obtained when a foliar fun was used. Although very few studies examined the impact of row spacing on plant diseases, the few that have would indicate that there could be some potential ben terms of disease reduction with wide row spacings. For the sake of providing a recommendation, we can argue that using wide row spacings will not necessarily in plant diseases.

3.7 Are adjustments in fertilizer management practises required when using wide row spacings?

One aspect of fertilizer management that requires special attention is placement. from 9" to 12" will increase the concentration of the fertilizer near or with the 30%. Consequently, it is advised that care and attention be given to fertilizer p Even with crops like field pea, where phosphorus is sometimes the only fertilizer reductions on the order of 10-15% in plant stands can occur when the fertilizer i with the seed. It is therefore recommended that every effort be made to provide 5 separation between the seed and fertilizer to minimize the risk of crop damage.

3.8 What are some of the implications of row spacing for the wetter parts of the prairies?

One of the most important advantages of using wide row spacings has to do with ability to seed through heavy crop residues. In the wetter areas of prairies, this is cri of the higher level of crop residues being produced. However when heavy crop residues are combined with heavy textured soils, using wide row spacings won't resolve all problems because of the soil remaining wet for too long and delaying the seeding operation, not to mention making it very challenging. However, the other advantages of wide row spacing in terms of equipment, timeliness of operation, reduced field ti tractor hours still apply.. There may also be some advantages in terms of reduction foliar and root diseases.

3.9. Why do recommendations about row spacing effects on grain yield vary among the various crops and studies done in Western Canada for the last 25-30 years?

All field experiments have some inherent biases built into them. In some cases, biases can have a significant influence on the results. Examples of biases in the row spacing studies might involve: (1) confounding effects with seeding rates (2) the calculation of effective harvested area (3) border effects which become magnified when only a few rows are used per plot (4) problems with fertilizer placement fav one spacing over another due to availability or damage. We therefore contend that major reason why there are so many conflicting results with the effects of row 5 grain yields has to do with unplanned biases introduced into the studies and having effect on the results. The fact that high yields can be maintained with spacings 12" is a clear indication that the high yield potential of crops will not be comp long as plant populations are maintained and fertilizer is managed properly, pro should not experience reduced yields because of the use of wide row spacings. How it is possible that under certain circumstances, yields on wide row spacings may be lower and it is important through appropriate research to try and define what conditions might