In the lower latitudes of the Temperate Zones, where the growing season is long and the dormant period correspondingly short and mild, we find agriculture based upon clearly distinguished winter and summer crops, as in the northern Punjab (30 deg. to 34 deg.  N. L.);[1447] or producing a quick succession of valuable crops, where the fertility of the soil can be maintained by manures or irrigating streams, as in many of the warmer Southern States and in Spain[1448] respectively.  In Argentine, where tillage is extensive, land abundant, and population sparse, where, in fact, “skimp farming” is the rule, the shrewd cultivator takes advantage of the long growing season to stretch out his period of sowing and reaping, and thus tills a larger area.  The International Harvester Company of America, investigating the reason for the small number of reaping machines employed in Argentine in proportion to the area under cultivation, found that the simple climatic condition of a long growing season enabled one reaper to serve about twice the acreage usual in the United States, because it could work twice as long.[1449]

[Sidenote:  Zones of culture.]

Over and beyond slight local variations of climate and season within the same zone, which contribute their quota to economic and historical results, it is the fundamental differences between the hot, cold and temperate climatic zones that produce the most conspicuous and abiding effects.  These broad belts, each with its characteristic climatic conditions and appropriate civilization, form so many girdles of culture around the earth.  They have their dominant features of heat and cold, variously combined with moisture and aridity, which give a certain zonal stamp to human temperature and development.

The two cold belts have little claim to the name of cultural zones, since their inability to support more than an insignificant population has made them almost a negligible factor in history. [Compare maps pages 8, 9, and 612.] The discoveries and settlements of the Northmen in Greenland remained a barren historical event, though the vikings’ ships reached a new hemisphere.  Iceland is the only land in this sub-arctic region which ever figured upon the stage of history; and its role was essentially passive.  Such prominence as it acquired was due to its island nature and its situation in a swirl of the Gulf Stream, which ameliorates the worst climatic effects of its far northern location, and brings it just within the upper limit of the temperate belt.  The wide sub-arctic lowlands of Russia and Siberia, which, from the Ural Mountains to the lower Amur River, stretch the cold zone well below the sixtieth parallel, have at times in the last three centuries and especially in the past decade thrown their great mass into the scale of eastern Asiatic history.  This has been possible because the hot summer characteristic of continental climates forces the July isotherm of 20 deg.C. northward over the vast heated surface of Asia nearly to the sixtieth parallel, well within the borders of Siberia.  It gives that belt the short but warm growing season with protracted hours of sunshine which is so favorable to cereals, lending to Omsk, Tomsk, Vitimsk and all the stretch of Russian settlements in Siberia, an admirable summer climate like that of the Canadian Northwest.[1450]