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University of Manitoba Faculty of Agricultural and Food Sciences Department of Plant Science

Glenlea Long-Term Crop Rotation:
History and Description

Celebrating 25 Years of Organic Research at Glenlea

The Glenlea Long-Term Rotation Study is teaching us valuable lessons about organic crop management as well as the ecology of the system. Learn more in the video produced for our 25th anniversary.


History of the Glenlea Long-Term Crop Rotation Study

This long-term, large-scale study was established in 1992 and is completing its 25th year in 2016. The Glenlea study contains many different crop production systems, including western Canada's oldest organic cropping systems. This study is unique in that each replicate contains a one acre restored prairie grass planting, which serves as a benchmark site for soil and environmental measurements.

The objectives of the study are:

  • To compare the biological and economic performance of conventional, low input and organic crop production systems
  • To monitor the impact of crop rotation and input level on pest population dynamics (annual and perennial weeds, insects, and crop diseases)
  • To determine the long-term effects of different cropping systems on soil and environmental quality, using a restored tallgrass prairie treatment as a benchmark
  • To provide a facility for undergraduate and graduate student training

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.

Original Experimental Design

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. 

For results from the first twelve years, visit Glenlea Long-Term Rotation: Historical Research Results.

Current Experimental Design

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. Plots were split and the rotation was fully phases, meaning that all rotation crops appear in the rotation each year.

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

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

These two rotations are conducted under both organic and conventional methods. The soybean crop in the organic grain only rotation is substituted with a mixture of annual legumes which are green manured.

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:  

  • Crop yield and quality
  • Weeds
  • Soil nutrient status
  • Soil erodibility
  • Energy use and efficiency
  • Mycorrhizal colonization
  • Carabid beetles
  • Nematodes
  • Disease
  • Economics

More on the Glenlea Study

Copyright and Liability

This page imported Nov 2012 from the former Glenlea Long-term Study website.
Last updated October 2016.