关键词: 
Mollisols /
classification /
sustainability /
soil fertility /
no tillage /
South America

摘要: Mollisols are common in South America. They cover about 8.87 × 107 ha, 1.3 × 107 ha and 4.3 × 106 ha in Argentina, Uruguay
and Southern Brazil respectively, which is 11.5% of the world total. Most of South American Mollisols were developed on Pleistocene and
Holocene sediments and lie within the limits of the temperate zone, though the extreme north is bordering subtropical and the extreme
south is within a cold-temperate zone. All suborders of Mollisols occur in Argentina, the most extensive being Udolls followed by Ustolls,
whereas only Udolls, Aquolls and Albolls occur in Uruguay. Vertisols in Uruguay have many properties similar to Mollisols, and the
occurrence of Vertisols is strongly associated with Mollisols. The Pampean Mollisols are a significant component of the global breadbasket
of modern times. The main Argentine crops are wheat, corn, sorghum, barley, soybeans and sunflower, while Mollisols in Uruguay remain
mostly dedicated to cattle and sheep grazing though crop production has been increasing very rapidly in the last decade. Throughout
South America, research has shown that Mollisols are experiencing losses of soil organic matter and nutrients, and degradation of physical
properties after long cropping periods, resulting in soil scientists calling for increased conservation practices to reduce future losses and a
deterioration of soil quality, and thus a more sustainable agriculture in the region.