Crop On Crop - How Common?

Table 1. Previous crop (stubble) distribution (%) of large acreage fields (>120 acres) sown to the major field crops in Manitoba during the period 1994-1998 (source - Manitoba Crop Insurance Corporation).
 

Stubble Crop	Crop Sown
	RS Wheat	Barley	Oats	Argent. Canola	Flax	Field Peas
	Percentage of Sown Acreage
All Wheats	30	40	32	68	72	75
Barley	4	15	7	14	11	10
Oats	2	3	9	6	5	4
Canola	44	30	30	2	8	4
Flax	11	6	13	4	1	3
Field Peas	3	2	1	1	0	0
Other	6	4	8	5	3	4

Type on Type - How Common?

Table 2. Previous crop class (stubble) distribution (%) of large acreage fields (>120 acres) sown to the major field crops in Manitoba during the period 1994-1998 (source - Manitoba Crop Insurance Corporation).
 

Stubble Crop	Crop Sown
	RS Wheat	Barley	Oats	Argent. Canola	Flax	Field Peas
	Percentage of Sown Acreage
Cereal Crops	39	60	52	90	90	90
Broadleaved Crops	61	40	48	14	11	10

Crop Rotation Bushel Yields

Table 3. Five year (1994-1998) average yield of major Manitoba crops sown on large (>120 acre) fields of various previous crops (stubble) in rotation (source - Manitoba Crop Insurance Corporation).
 

Crop Sown	Previous Crop (Stubble)
	RS Wheat	Barley	Oats	Arg. Canola	Flax	Field Peas
	Five Year Average Yield (Bu/Ac)
RS Wheat	31	33	34	36	35	37
Barley	60	52	56	62	64	64
Oats	81	74	71	88	87	82
Arg. Canola	28	28	29	25	29	32
Flax	21	21	20	19	14	NSD*
Field Peas	33	33	30	29	26	NSD*

*NSD - Not Sufficient Data

Crop Rotation Relative Yields

Table 4. Relative yield response (% of 1994-1998 average) of major Manitoba crops sown on large (>120 acre) fields of various previous crops (stubble) in rotation (source - Manitoba Crop Insurance Corporation).
 

Crop Sown	Previous Crop (Stubble)
	RS Wheat	Barley	Oats	Arg. Canola	Flax	Field Peas
	Relative Yields (% of Average)
RS Wheat	90	98	99	106	103	108
Barley	101	88	97	105	107	107
Oats	99	90	87	108	107	100
Arg. Canola	100	101	103	88	104	113
Flax	102	102	101	92	69	NSD*
Field Peas	101	101	93	89	82	NSD*

*NSD - Not Sufficient Data

Figure 1. According to Bourgeois & Entz (1996) although the rotational benefits of non-cereal crops prior to wheat has been observed on small plots, few quantitative studies are available at the field scale. This graph summarized the yield data reported to MCIC between 1982 and 1993 from fields 160 acres in size throughout agro-Manitoba. During this period, the yield of wheat following flax, peas and canola was on average 16%, 11% and 8% higher, respectively, than wheat following wheat. In one year (1987) the yield of wheat increased an average of 41% following a field pea crop.