Experiment Description
The Glenlea long-term rotation study is located 20 km south of Winnipeg, Canada (Lat/Long. N 49,39,0 / W 97,7,0). The soil type is a rego Black Chernozem consisting of 12% sand, 32% silt, 55% clay, with an organic matter content of 5.5%. Annual precipitation is 535 mm with approximately 30% of annual precipitation as snow. The average frost-free period is 120 days and the growing degree days (>5 C) is 1755.

The study was established in 1992 and has since undergone several modifications.

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Experimental design is a split plot randomized complete block with three replicates (See Plot Plan 1). Main plots are composed of the crop rotation treatments and measure approximately 90 × 60 m. Subplots consist of four combinations of crop inputs and measure approximately 45 × 30 m. Each block also contains a restored prairie treatment (45 × 60 m).

Crop Rotations
Three 4-year crop rotations were included in the study. Flax served as a "test crop" in the 4th year of each rotation to allow for rotation comparisons. Flax was chosen because it is not a very competitive crop and the rotational effects on weed populations should be evident.

The three crop rotations were:
1) WPWF: Wheat-Pea-Wheat-Flax
2) WGmWF: Wheat-Green manure (clover)-Wheat-Flax
3) WAAF: Wheat-Alfalfa-Alfalfa-Flax

Crop Inputs
The crop input treatments consisted of four combinations of herbicide and fertilizer inputs. Herbicide applications were based on economic thresholds and fertilizer applications were based on annual soil tests.

The four crop input treatments were:
F+H+: fertilizer and herbicide added (conventional system)
F+H-: only fertilizer added
F-H+: only herbicide added
F-H-: no inputs (organic system)

Prairie
The prairie contains a mixture of cool and warm season grasses typical of the tallgrass prairie that once dominated southern Manitoba. Species include: big bluestem, indian grass, switchgrass, western wheatgrass, northern wheatgrass and slender wheatgrass. The prairie has been managed twice with a prescribed burn; once in 1995 and again in 1997.

Historical Research Results

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Originally, sweetclover was used as the green manure crop in Rotation 2; however, it was replaced by red clover in 2001 due to poor stand establishment.

In 2002 the crop rotation treatments were expanded to include alternative 2nd and 3rd year crops (See Plot Plan 2). Four sub-subplots measuring 4 × 26 m were established within each subplot and each main rotation was divided into four modifications. One of the WAAF modifications includes a fall application of composted beef manure after the alfalfa stand termination.

The modified rotations were:
1) WPWF: Wheat-Pea-Wheat-Flax
WPOF: Wheat-Pea-Oat-Flax
WPRF: Wheat-Pea-Fall rye-Flax
WPWO: Wheat-Pea-Wheat-Oat

2) WGmWF: Wheat-Green manure-Wheat-Flax
WGmOF: Wheat-Green manure-Oat-Flax
WGmRF: Wheat-Green manure-Fall rye-Flax
WGmWO: Wheat-Green manure-Wheat-Oat

3) WAAF: Wheat-Alfalfa-Alfalfa-Flax (in two sub-subplots)
WAAmF: Wheat-Alfalfa-Alfalfa (manure)-Flax
WAAO: Wheat-Alfalfa-Alfalfa-Oat

Beginning in 2004, research energies have been focused on maintaining and sampling the conventional (F+P+) and organic (F-P-) crop input subplots and the other two were discontinued.

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The Glenlea Study underwent major modifications in 2004. The current experimental design is a randomized complete block with 3 replicates. Two main rotation types are included in the study; a grain only rotation, and grain-forage rotation. All rotation crops appear in the rotation each year.

Rotation 1. Grain only rotation: flax-oat-fababean-wheat

Rotation 2. Grain-forage rotation: flax-alfalfa-alfalfa-wheat

These two rotations are conducted under both certified organic and conventional methods. The fababean crop in the grain only rotation is managed differently in the organic and conventional systems. In the organic system, the fababean crop is green manured while the fababean is grown for seed in the conventional system.

In addition to the cropping systems, the study continues to include a native grass planting (1, 1-acre grass prairie in each of the 3 replicates).

Measurements include:

Current Research Results