Fertilization and mowing effects on unimproved mixed-species hayfields in Québec, Canada

N. S. Eriksen-Hamel and J. K. Whalen

Perennial hayfields are an important component of livestock farming systems in eastern Canada covering up to 40% (2.3 million ha) of the agricultural land. At least a third (800,000 ha) is defined as unimproved hayfields, not having had recent improvements such as cultivation, seeding, fertilization or weed control.

These unimproved hayfields are gradually invaded by grass and weed species, which can lead to significant reductions in productivity. We evaluated the response of two unimproved mixed-species hayfields (Bromus-Poa and Pleum-Lolium) in Québec to fertilization regimes (inorganic fertilizer, liquid dairy manure or no fertilizer) and intensive mowing (every two weeks or unmown, during a 12 week period).

Dry matter and nutrient yields were similar in plots receiving inorganic and dairy manure fertilizers, but dry matter yield was 0.6 to 2.8 t ha^-1 greater in fertilized plots than the unfertilized plots.

Repeated mowing reduced dry matter yield by 1.5 to 2.7 t ha^-1, however, tissue nutrient concentration and nutrient yield were greater in mown than unmown plots.

Soil NO₃- and microbial biomass-N concentration were significantly lower in fertilized plots that were mown every two weeks than unmown during the study period.

Frequent mowing may be a management option that can reduce soil residual-N and thus limit NO₃- leaching from mixed-species hayfields.


Source
Crop Science (2006) 46: 1955-1962


Contact
Joann K. Whalen
Dept. Natural Resource Sciences,
Macdonald Campus of McGill University
21,111 Lakeshore Rd., Ste-Anne-de-Bellevue,
QC, H9X 3V9
Joann.whalen@mcgill.ca


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Posted March 2007