Southdown sheep no longer economical and smaller flocks averaged only 135 ewes apiece. The use of artificial fertilizers had gained ground, and the combine-drill, which sowed grain seeds and fertilizer together, rendered close-folding by sheep unnecessary. Gradually surrendering to basic arable farming changes, the Southdown became largely a grassland breed. During the interwar years, the United Kingdom was known for farm animal breeding, and pedigreed Southdowns were still being exported to most parts of the world, especially New Zealand. In 1937, the number of exported Southdowns reached 459 head. During the Great Depression, a severe and prolonged fall in the prices of
Southdown sheep kohl rabi and other forage crops, the folding system took off, increasing in parallel with expanding human population. The system reached its zenith from about 1845 to 1880. The 20th century brought the establishment of pedigree recording. By 1911, 359 registered Southdown flocks contained some 114,495 breeding ewes throughout Britain. Much remained the same until the First World War, when the Southdown flocks declined with some rapidity, as shepherds and farm workers went off to war. By 1922, the 359 pedigree flocks had shrunk to 245. From then until 1939, the registered Southdown flocks numbered around 200. Folded flocks were