University of Manitoba: Natural Systems Agriculture: GLTR 2005 Yield
University of Manitoba Faculty of Agricultural and Food Sciences Department of Plant Science

Glenlea Long-Term Crop
Rotation: 2005 Yield Results

Crop Yields and Economics

The year 2005 was a disastrous year in many parts of Manitoba with excessive precipitation throughout the early part of the season. Cereal crops in the rotation were seeded early (first week of May) and hence were badly damaged by the early season precipitation. Cereal yields were very low (Table 1) and neither the wheat or oat crops resulted in positive net returns (Table 2). Organic cereal yields were significantly lower than conventional yields in both the forage-grain and the grain only cropping system. Averaged across both of these cropping systems, organic cereal yields were only 20% the yield of conventional crops.

Flax was seeded in mid-June and a long frost-free period in September allowed this late seeded crop to mature. The main difference in flax yields was due to rotation with flax in the grain only rotation yielding only 50% as much as flax in the forage-grain rotation (Table 1). Organic flax yields were between 88% and 66% of conventional yields in the forage-grain and grain only rotations, respectively.

Fababean yielded very well in the grain only rotation (Table 1). Fababean is a flooding tolerant crop and well adapted to wet seasons like 2005. The fababean green manure crop in the grain only organic rotation produced over 2000 kg/ha of legume dry matter; based on 3% N in the legume biomass, this translates into approximately 65 kg N/ha.

No alfalfa yields are presented for the 2005 crop year. Alfalfa was grown, however given that the rotation moved to a fully-phased format in 2005 (all rotation crops appear each year from now on), both alfalfa plots were seedling crops. Therefore, the economic analysis assumes that alfalfa hay crops provide $0 net return/acre. It should be noted that this move to a fully-phased format will greatly enhance the value of the Glenlea study to the farming and extension community.

Table 1. Yields of cereal, flax and fababean greain and green manure crops grown at the Glenlea long-term crop rotation study in 2005.
Crop Rotation Crop Input System Crop Yield kg/ha (bu/ac)
Wheat Flax Oat Fababean
Forage-grain system Conventional 1025
- -
Organic 334
- -
Grain only Conventional 891
1421 grain
Organic 83
Green manure plowdown = 2156 (64.7 kg N/ha) + 1116 weeds = 3272
Statistical Analysis Rotation (R) ns ** - -
System (S) ** ns ns (0.13) -
R x S ns ns - -
CV (%) 41 31 61 -

ns, not significant
**, significant at P<0.01
CV, coeffient of variation

Table 2. Gross returns (R), cost of production (C) and net returns (N) for cereal, flax and fababean grain and green manure crops grown at Glenlea in 2005. Rotation net returns averaged across a 4 year rotation.
Crop Rotation Crop Input System Net Returns ($/acre)
Wheat Flax Oat Fababean 1Rotation net return/yr over a 4-yr rotation
Forage-grain system Conventional R 62.32
C 125.00
N -62.68
R 146.40
C 130.00
N +16.40

R 39.80
C 80.00
N -40.80

R 302.40
C 90.00
N +212.40
Grain only Conventional R 54.12
C 125.00
N -70.88
R 91.80
C 130.00
N -38.20
R 61.40
C 100.00
N -$38.60
R 169.60
C 90.00
N +79.60
Organic R 9.60
C 80.00
N -70.40
R 138.60
C 90.00
N +129.60
R 12.60
C 100.00
N -87.40
Green manure
R 0.00
C 60.00
N -60.00

Calculation of returns based on the following prices:
Wheat: Conventional $4.10/bu; Organic $8.00/bu
Flax: Conventional $6.00/bu; Organic $14.00/bu
Oats: Conventional $2.00/bu; Organic $3.00/bu
Fababean: Conventional $8.00/bu
1Assumes that alfalfa hay in rotation had a $0 net return.

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This page created June 2006.