An agroclimatology of southern Manitoba

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Dunlop, S.
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A quantitative assessment of the spatial distribution of Southern Manitoba's agroclimatic resource base was undertaken. The research objectives were twofold: i) to establish a data base, using readily available climatic data, sufficient to evaluate the climatic resources and/or potentials of this area with respect to the utilization of this knowledge in agricultural planning; and ii) to statistically analyse this data base so as to describe the climatic risks and/or advantages associated with various regions within the province. Thermal and moisture conditions within the province were studied using specially developed computer programs. Past records of daily climatic data from meteorological stations within the study area were used to derive agroclimatic parameters which relate the effect of temperature and moisture to plant growth and development. The parameters derived focused on three essential climatic features: i) the occurrence of frosts in the spring and fall and the subsequent lengths of the frost free periods, ii) values of heat accumulated during the growing season; and iii) the analysis of soil moisture conditions under three different crops. Probability analysis was carried out on each parameter at the 50%, 25% and 10% risk levels. The analysis undertaken showed the optimum climatically suited area for intense agricultural crop production is the Red River Valley. Thermal contraints in the area west of the escarpment and in the south east section of the province prevent these areas from being suitable for crops requiring a long frost free period and high accumulated heat requirements. The entire study area is generally suited to cereal production, but grain corn is feasible in only a few selected regions. Moisture constraints to high productivity are evident in the south west region of the province in areas such as Souris, Pierson and Brandon.