¹ Indian Head Research Farm, Indian Head, SK; ² Brandon Research Centre, Brandon, MB; Saskatchewan Irrigation Development Center, Outlook, SK; ³ Lacombe Research Station, Lacombe, AB; ⁴ Brandon Research Center, Brandon, MB; ⁵ Saskatchewan Agriculture and Food, Scott Research Farm, Scott, SK; ⁶ Melfort Research Farm, Melfort, SK; ⁷ Swift Current Research Centre, Box 1030, Swift Current, SK; ⁸ Montana State University, Bozeman, Mt; ⁹ AG-Quest, Minto, MB.

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

Although one could argue that for certain crops the risk of reduced yields with row spacings in the range of 10-12" is frequent enough to cause concern, one has to keep in mind what the absolute differences are and what the overall benefits are when considered on a whole farm basis. There are some implied economic and agronomic benefits with the use of wider row spacing under no-till that are never considered in the field studies. Some of the agronomic benefits are reduced soil disturbance and the ability to take advantage of the stubble height for trapping snow and the micro-climatic benefits. Some of the economic benefits are reduced draft, reduced costs due to fewer openers, and reduced energy costs. In deciding which way to go, a producer has to appreciate the risks. Based on the results presented, it appears that there were enough positive studies to show that in absolute terms, high yields can be obtained with 12" spacings without compromising the yield potential. When the yield potential was compromised, it could be explained on the basis of confounding effects due to seeding rates, experimental design and methodology. In some cases fertilizer placement and availability resulted in biases against the wide row spacing.

In order to establish the full potential of wide row spacings, it has to be evaluated in the context of a zero tillage production system because it can utilize the benefits of standing stubble and the mulch effect of crop residues.

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

In order to understand the discussion about row spacing, you have to go back to the early eighties and remember all the excitement about European intensive cereal production techniques 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 and fungicides to control plant diseases. However, from the mid-eighties to the early nineties, severe problems with heat and drought led to low yields and/or crop failures on the prairies. This resulted in an urgency to develop crop production systems that would protect the soil from further degradation and conserve more water. This culminated with the adoption of zero tillage, sometimes called low disturbance direct seeding systems and its adoption on a wide scale.

In the process of developing and promoting these new production systems, producers faced an important dilemma. Tall stubble for trapping snow can create problems for the seeding operation because the rule of thumb is that the height of stubble should generally not exceed the 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 with the responsibility of seeking a balance between stubble height for conserving moisture and the need 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 or not the yield penalty suffered from using 12" row spacings could be offset given the benefits in terms of tall stubble for trapping snow, low soil disturbance, draft power requirements and cost of purchasing new equipment, ease of seeding and whether changes could be made to avoid the yield penalty when using a 12" spacing.

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

2.1 Lentil

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

Table 1: The effects of row spacing on grain yield (lbs/acre) in lentil at Morden, MB using 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 Ali-Khan and Kiehn, 1989. Can. J. Plant Sci. 69:377-381.

Table 2. The effects of row spacing on plant populations (#/m²) and grain yield (lbs/ac) in Lentil at Unity and Swift Current, 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
Row Spacing (")	Seeding rate (lbs/acre)	Plants/m2	Grain Yield (lbs/acre)
8	95	70a	1361
	64	59b	1298ab
12	95	70a	1235bc
	64	51b	1181c
Means followed by the same letter are not significantly different at p=0.05. From McConkey and Miller, unpublished data for the period 1995 - 1998.

2.2 Field Pea

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

Further research is required under a wide range of conditions to determine the effect of row spacing on field pea.

Table 3. The effects of row spacing on plant populations (#/m²) and grain yield (bus/ac) in field pea at Unity, SK in 1994 and Swift Current, SK from 1995-1998.

Unity, SK	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 for the Unity site.

Swift Current, SK		Normal Leaved (1995-1998)		Semi-leafless (1005-1998)
Row Spacing (")	Seeding Rate (lbs/ac)	Plants/m2	Grain Yield (lbs/ac)	Plants/m2	Grain Yield (lbs/ac)
8	155	41a	2258	42a	2095a
	104	32b	2153	32b	1976a
12	155	37a	2297	38a	2065a
	104	31b	2077	31b	1823b
Means followed by the same letter are not significantly different at p=0.05. Taken from McConkey and Miller, unpublished data..

2.3 Canary Seed

Only one study was found for this crop and there was no difference in yield between a 9 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, 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.:69:1193-1198.

2.4 Oat

Only one study with oat was found and there was no difference in yield between the 6 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.

Row Spacing (inches)	1966	1967
6	99.5	56.6
12	101.4	55.8
Taken from Austenson and Larter, 1969. Can. J. Plant Sci. 49:417-420.

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 between the other studies. The important point to note is that high yields of flax can be obtained with 12" row spacings and providing that adequate attention is given to fertilizer placement, maximum economic yields in flax are possible with 12 inch row spacings. It should be noted that flax is very susceptible to fertilizer damage and fertilizer should be placed away from the seed to minimize seedling damage. Flax is not a competitive crop and as such careful attention to weed control is necessary at all times, and possibly more so if wide row spacing is combined with high soil disturbance.

Table 6. The effects of row spacing on grain yields (bus/ac) of flax at five 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: 375-382. Zero-tillage.					R. Blackshaw, pers. communication. Zero tillage			Stevenson and Wright, 1996. Can J. Plant Sci.76:537-544. Conventional tillage

Swift Current (1995-1998)
Row Spacing (inches)	Plants/m-2	Grain Yield (lbs/acre)
8	151a	21a
12	108b	19b
Means followed by the same letter are not significantly different at p=0.05. Taken from McConkey and Miller, unpublished data..

2.6 Durum

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

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	19931	19941	19931	19941	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	41	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: 703-711 and 1 Lafond (unpublished results).									Solid Seeding	76.0
									B. Irvine, pers. communication

Swift Current 1995-1998
Row Spacing (")	Seeding Rate (lbs/ac)	Plants/m2	Grain Yield (bus/ac)
8	90	129a	34a
	60	97b	31a
12	90	97b	28b
	60	86b	27b
Means followed by the same letter are not significantly different at p=0.05. Taken from McConkey and Miller, unpublished data..

2.7 Winter Wheat

Research trials looking at row spacing in winter wheat span the years 1985 to 1994. During those years, conclusions of no row spacing effects on grain yield all the way to a linear decrease in grain yield with row spacing have been reported (Table 8, 9, 10 and 11). It is very difficult to conclude what is the best approach given that producers want to use practises that will give them the greatest probability of success for attaining the highest yield possible. In Table 9, a difference was observed between 7" and 10" but then no difference between 10" and 11". It is important to note, that high yields of winter wheat were reported with wide row spacings and that at those high yield levels, using a narrow row spacing did not improve grain yields. Although a definitive conclusion cannot be made about the best row spacing to use, it is important to make sure that adequate plant populations are established and that damage as a result of seed-placed fertilizer be minimized. In the brown soil zone at Swift Current, no difference in row spacing between 11" and 14", were reported, regardless of stubble and year except for one year but the 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.

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, unpublished results, Indian Head, SK.

Table 9. The effects of row spacing on grain yield (bus/ac) of winter wheat at selected sites in Northeast , SK.

Row Spacing (")	Melfort1 (1986)	Aylsham1 (1986)
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.

Table 10. The effects of row spacing on grain yield (bus/ac) in winter wheat at selected locations in SK.

	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
1Averaged over 6 seeding rates ranging from 0.3-1.8 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	15.4	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, Universisty of Saskatchewan, S'toon, Sk.

Table 11. The effects of row spacing on grain yields (bus/acre) of winter wheat in the brown 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	40	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. 76:207-214.

2.8 Barley

A large number of row spacing studies in barley were found and unlike winter wheat, the evidence was such that the greater majority most of the studies showed no effect on grain yield due to row spacing (Table 12, 13, 14). In this case, it is easy to conclude that with barley, high 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 locations resulted in no significant difference between row spacings ranging from 6-12". A drop in yield was only observed at 16" (Table 14). However, in situations where no herbicides are used, as would be the case for in organic production, barley yields were higher with higher seeding rates 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, SK and Brandon, MB.

Row Spacing (inches)	Indian Head1 (zero-till)						Indian Head2 (summerfallow)			Brandon3 (zero-till)
	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: 74:703-711 2 Lafond and Derksen, 1996. Can. J. Plant Sci. 76:791-793. 3 Lafond et al., 1996. Better Crops 4:20-22.

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. 49:417-420.

Table 14. The effects of row spacing on plant populations and grain yield in barley at Unity, Foam Lake and Naicam, in SK.

	1994
Row Spacing (inches)	Plants/m2	Grain Yield (bus./acre)	Plants/m2	Grain Yield (bus./acre)	Plants/m2	Grain Yield (bus./acre)
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	30.0	90	23.0	80	27
16	130	30.0	90	18.0	90	35
Taken from annual reports prepared by Eric Johnson for projects funded by the Farm Based Canada Saskatchewan Green Plan Agreement.

2.9 Spring wheat

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

Table 15. The effects of row spacing on grain yield (bus/ac) of spring wheat at Indian Head, SK and Brandon, MB.

	Indian Head1 (zero-till)						Indian Head2 (conventional-till) (summerfallow)			Brandon3 (zero-till)
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: 74:703-711 2 Lafond and Derksen, 1996. Can. J. Plant Sci. 76:791-793. 3 Lafond et al. 1996. Better Crops 4:20-22.

Some studies showed a yield reduction from 6-9" but no differences between 6 and 12" (Table 17). In some, yield differences are observed in certain years favouring narrow row spacing but not in others, even though the yield levels are the same no difference (Table 16).

Table 16. The effects of row spacing on grain yield (bus/ac) for spring wheat at different locations in Saskatchewan.

	Scott (1985-86)1		Melfort1
Row Spacing (inches)	Plants/m2	Grain Yield (bus/ac)	Grain Yield (bus/ac)
4.5	171	60.2	74.8
9.0	136	54.4	61.5
18.0	107	45.8	-
1Averaged 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
1Averaged 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.

Swift Current (1995-1998)
Row Spacing (inches)	Seeding Rate (lbs/ac)	Plant/m2	Grain Yield (bus/ac)
8	60	183a	29a
	40	86bc	28ab
12	60	97b	26bc
	40	75c	26c
Means followed by the same letter are not significantly different at p=0.05. Taken from McConkey and Miller, unpublished data.

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

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

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 Side-Band Opener	38	37
Paired Row	38	37
Sweep	37	34
	Zero Tillage
Narrow Side-Band Opener	34	33
Paired Row	37	36
Sweep	34	32
Xie, H. S., D.. R.. S.. Rourke and A. P. Hargrave. 1998. Effect of row spacing and seed/fertilizer placement on agronomic performance of wheat and canola in zero tillage systems. Can. J. Plant Sci. 78:389-394

Table 19. The effects of row spacing on the yield of spring wheat (bus/acre) at Melfort, Brandon and Beaverlodge for the period 1995-1998.

Row Spacing	Melfort	Brandon	Beaverlodge
9"	50.6	51.3	25.2
12"	48.3	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 on canola but for this discussion we restricted ourselves to discussing information developed in Western Canada. It is generally accepted that higher seeding rates and narrow row spacings result in greater weed competition. However, these conditions can result in greater lodging potential and higher incidences of crop diseases. Since direct seeding openers are expensive and wider spaced openers clear trash better, it would be a great advantage if row spacings of at least 12" could be 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 narrow 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's competitive ability with weeds. It is my opinion that a uniform stand which emerges quickly is more important than row spacing in the normal 6-12" range of row spacings. While a narrow row spacing (more openers) will place seed in contact with a greater volume of soil and may improve the uniformity of plant emergence this is also possible using superior openers capable of placing seed shallow on a moist and firm seed-bed even on wider rows. When good seed to soil contact allows rapid and uniform plant emergence, the value of narrow row spacings is 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 spacings. Under centre pivot irrigation, where this work was done, evaporation from the soil surface is of limited 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, we assume hand weeding was done. Hand weeding would tend to favour narrow row spacings since 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 the differing number of times the operator walked over the field. While some studies report yield reductions using current management practices on fallow these results differ from those obtained by the Canola Council under direct seeding conditions and under 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/tillage	% of 6" spacing
			3-4"	8-9"	12"	16-18"
Scott1	4	fallow	118		92
Winnipeg	3	fallow			81
Unity	3	stubble direct		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 ft Seeding Equipment Double disc press

Fertilization Phosphorous was seed placed at 0 and 22 lbs P₂O₅ /ac

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

Seed placed phosphorous fertilizer reduced plant numbers to a greater extent at the wide row spacings. In this study 12" spacings produced 8% less seed with or without fertilizer. The difference between the 8 and 12 inch spacings was less than between the 4 and 8 inch spacings. There was no effect of seeding rate on yield
although higher seeding rates increased plant 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/ac 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. 1985-89. 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 18' long Seeding Equipment Double disc press

Fertilization 34 lb/ac N as ammonium nitrate and 13 lb/ac elemental sulfur broadcast and 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 side of the yield test being removed just prior to harvest. In this trial, 12" rows gave 19% lower yields than rows spaced 6" apart. All seeding rates greater than 1.3 lb/ac had similar yields. The narrower row spacings had greater leaf area throughout the season and the higher seeding rates gave greater leaf area early in the season. The greater weed competition from narrow rows and high seeding rates is due in large part to the more rate development of canopy. It has been reported that some of the hybrid canola cultivars have the genetic potential to rapidly develop a large crop canopy (Table 22).

Table 22. Effect of row spacing on plant numbers and yield of rapeseed in Manitoba 1985-86.

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. 70:127-37.

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 rows 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 P₂O₅ broadcast and incorporated prior to planting. Seeding rates 6.2 and 12.4 lb/ac Previous Crop (not mentioned in report)

The extremely high yields resulting from the 3 inch row spacing are difficult to explain unless weed competition was high early in the season. Wider row spacings were not tested but it is interesting to note that yield differences between 6" and 9" spacings were very small relative to 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. 64:1011-13.

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 relative to wider row spacings. It is interesting to note that the largest differences are between 6" and 9" 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	1971	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