Average Crop Heat Units available for corn and soybean production in Eastern Canada

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Description

ACHU - more than just an average. The Corn Heat Unit system, now also known as Crop Heat Units (CHU), was developed in the 1960's and is used to recommend corn hybrids and soybean varieties which are best suited for production in specific CHU zones in various regions of Canada.

The Crop Heat Units shown on this map are average values based on the 1961-90 normal period for Ontario and Qubec. The values for the Maritimes are based on data from the 1956-85 period since this was the most recently available assessment. The map is subject to change as more climatic information becomes available in the future. Due to the influence of local soil and climatic factors such as slope, drainage, shelter and frost occurrence, it is generally impossible to estimate the CHU rating closer than 50 to 100 heat units for any location.

On an annual basis, CHU are highly variable and can be 250 units or more above or below the average value in some extreme years. Depending on location, about 100 to 150 CHU need to be subtracted from the average value to determine CHU exceeded at the 80% probability or risk level (i.e. 8 years in 10 will have at least this amount of CHU). For the 90% risk level, about 160 to 230 CHU must be subtracted from the average value. Information on the probability or risk of abnormally high or low CHU accumulation will help answer questions such as "how many CHU can I count on getting at least 9 years out of 10".

For more detailed information on the procedures for determining CHU and on the availability of CHU at various risk levels at specific locations in each region, consult the publications listed below, which are available on request.

Information was compiled by A. Bootsma, Agriculture & Agri-Food Canada, Research Branch, Eastern Cereal and Oilseed Research Centre, Ottawa, using references indicated below.

Map was prepared by the CanSIS unit.

Contact:
Andrew Bootsma
Agriculture and Agri-Food Canada
Eastern Cereal and Oilseed Research Centre
Ottawa, Ontario K1A 0C6
Tel: (613) 759-1526
Fax: (613) 759-1924
E-mail: BootsmaA@em.agr.ca

References

Bootsma, A. 1991. Risk analyses of heat units available for corn production in the Maritime provinces. Agriculture Canada, Research Branch, Land Resource Research Centre, Ottawa, Technical Bulletin 1991-8E. 49 pp.

Bootsma, A., Gordon, R., Read, G. and Richards, W. G. 1992. Heat units for corn in the MaritimeProvinces. Atlantic Committee on Agrometeorology Publication 92-1. 8 pp.

Bootsma, A. and Brown, D.M. 1995. Risk analyses of Crop Heat Units available for corn and other warm-season crops in Ontario. Agric. & Agri-Food Canada, Research Branch, Centre for Land and Biological Resources Research, Ottawa, Technical Bulletin1995-1E. 83 pp.

Brown, D.M. and Bootsma, A. 1993. Crop Heat Units for corn and other warm-season crops in Ontario. Ontario Ministry of Agriculture and Food Factsheet No. 93-119, Agdex 111/31. 4 pp.

Dub , P.A., Castonguay, Y., Ct , J. et Lonard, R. 1984. R valuation de la distribution des unit s-thermiques-mas au Qu bec. Conseil des productions vg tales du Qubec, Minist re de l'Agriculture, des Pcheries et de l'Alimentation, Gouvernement du Qu bec, bulletin technique no. 7. 49 p.

Bootsma, A., Tremblay, G. and Filion, P. 1999. Risk analyses of heat units available for corn and soybean production in Qubec. Agriculture and Agri-Food Canada, Research Branch, Eastern Cereal and Oilseed Research Centre, Ottawa, Technical Bulletin Contribution no. 991396. (in press).

Contact: Head, CanSIS