The same superficial, extensive til

The same superficial, extensive tillage, with abandonmentof fields every few years, prevails in the Tartar districts ofthe Russian steppes, as it did among the cattle-raising Ger-mans at the beginning of their history. Tacitus says ofthem, Arva per annos mutant et superest ager, commentingat the same time upon their abundance of land and theirreluctance to till. Where nomadism is made imperative byaridity, the agriculture which accompanies it tends to become fixed, owing to the few localities blessed with an irrigatingstream to moisten the soil These spots, generally selected forthe winter residence, have their soil enriched, moreover, by thelong stay of the herd and thus avoid exhaustion.87 Often, how-ever, in enclosed b&sins the salinity of the irrigating streamsin their lower course ruins the fields after one or two crops, andnecessitates a constant shifting of the cultivated patches;hence agriculture remains subsidiary to the yield of the pastures. This condition and effect is continuous along thetermini of the practised draining the northern slope of theKuen Lun into the Tarim basin.