Western Germany and Austria had a lot of small farms. When the men went to war, the women (and the old and the very young) replaced them. They were critical to the supply of food and other materials. From early in the war Germany drafted labour from Occupied Europe for farm work (and much else - they ended with over 11 million slave labourers).

>The fact that more women were not mobilized for war work is some¬
>
>times taken as one more symptom of the inability of the Nazi regime to
>
>demand sacrifices from the German population. In this respect it has
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>often been contrasted to Britain, where an increase in female partici¬
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>pation in the workforce was the key to sustaining the war effort. Such
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>comparisons, however, are completely misleading, since they ignore the
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>fact that the labour market participation of German women in 1939
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>was higher than that reached by Britain and the United States even at
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>the end of the war. In 1939, a third of all married women in Germany
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>were economically active and more than half of all women between the
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>ages of 15 and 60 were in work. As a result, women made up more than
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>a third of the German workforce before the war started, compared to a
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>female share of only a quarter in Britain. A year later, the share of
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>German women in the native workforce stood at 41 per cent, compared
>
>to less than 30 per cent in Britain. Not surprisingly, over the following
>
>years Britain caught up. But even in 1944 the participation rate for
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>British women between the ages of 15 to 65 was only 41 per cent, as
>
>against a minimum of 51 per cent in Germany already in 1939....As we have seen, the burden of maintaining the small peasant farms thatdominated German agriculture fell disproportionately on women'sshoulders. And as farm men were recruited away for the war, this burdengrew ever more arduous. In areas such as Wuerttemberg and Bavaria,with dense populations of peasant farms, female workforce participationrates already exceeded 60 per cent in 1939. It goes without saying thatby sustaining the food supply, Germany's farm women provided anindispensable service to the Nazi war effort.But, even allowing for this difference in economic structure, the German level of mobilization was greater than that in Britain. In Berlin, a major centre of both industrial and service sector employment, with virtually no farm workers, 53 per cent of women were at work in 1939. The same was true of the eastern industrial hub of Saxony. Even in the port towns of Hamburg and Bremen or the heavy industrial centres of the Ruhr, where the occupational structure was particularly unfavourable to female employment, 40 per cent of women of working age had jobs, matching the national average for Britain at the end of the war.

- Wages of Destruction, page 357 and 358
Edit: apologies for formatting