Quote:
Originally Posted by someone123
South Dakota is quite arid. Google says only a small percentage is irrigated. Aridity matters on the Canadian prairies as well. If you want to talk about agriculture, water supply is a basic factor along with soil nutrients, temperature, and sunlight.
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I'm not so sure about that. The Beauce (in the Paris Basin), which is the most productive wheat farmland of Europe, and which has no major river (the Seine and the Loire are to the north and to the south of the Beauce, and there's not much in between in terms of rivers), gets 202 mm of precipitation from April to July. In comparison, Pierre, South Dakota, gets 286 mm from April to July, Winnipeg gets 213 mm, Regina gets 253 mm, Calgary gets 269 mm. The Paris Basin is known for being quite dry, but that has never prevented it from being a major farmland of Europe, even away from the main rivers, able to feed the largest European city in the Middle Ages.
Judging from the stats, the Prairies seem quite dry in winter, when the vegetation is dormant, and they get their water in summer at the peak of plant growth, due to the monsoon effect which moves from the Gulf of Mexico as far north as the Prairies. In this respect, their climate is more akin to central China than to Western Europe (where our wet season is more in the winter, with dryer conditions in summer). That's why corn (which needs lots of water to grow) is more adapted to North America (east of the Rocky Mountains), whereas wheat (which needs dry conditions especially in June and July when it ripens) is more adapted to Europe, although we do also produce lots of corn now but with irrigation systems (whereas wheat usually doesn't require irrigation).