Over the centuries, the German vineyard has expanded and contracted, often in response to the price and availability of grain. See german history and map there. Many of Germany’s best vineyards are on the steepest slopes, quite unsuited to anything other than the vine. Overlooking the Rivers rhine, Neckar, Main, Nahe, Ahr, mosel and its tributaries, their high cost of cultivation is justified only by the quality of the wine they can produce. In the steep vineyards, three times as many man-hours are spent tending the vine as is the case on flat or gently sloping terrain, where the natural position of the vine-grower is on the seat of a tractor.