SOIL CLASSIFICATION What is purpose of classification Chaos

SOIL CLASSIFICATION

What is purpose of classification? “Chaos was the rule of nature; order was the dream of man”. Henry Adams

How would you go about classifying soil?

Ethnopedology • Study of folk soil knowledge • “folk”, “traditional”, “indigenous”, “local” • • Soil knowledge held by people who have occupied land for a long time Many ways of knowing • Western science looked down on local soil knowledge as unscientific. • Folk soil knowledge uses spatial and time scales much more relevant to sustainable agriculture.

Local soil knowledge • Time-tested • Strategies that have been tried over centuries (or millennia) compared to < 100 yrs of industrial agriculture • Provides insights about human responses to change (climate change, soil erosion) • Many properties used (taste!, texture, color, etc) but all are about function of soil in land use (need for water, nutrients, aeration, support) • Does not imply that indigenous groups have not substantially altered land or caused environmental degradation problems; can learn from mistakes, too

2000 BC to 1500 AD

Maya occupation of Yucatan peninsula • 1200 BC to AD 1300 How did the Maya manage to feed millions of people for thousands of years in an area that is today sparsely populated and agriculturally poor?

Maya Lowlands Highlands

Climates of Maya Lowlands: BS semi-arid steppe Aw tropical savanna Am tropical wet-dry Af tropical rainforest

Agricultural adaptive regions in the Maya lowlands

Lari, Peru • 1500 yrs agriculture • Terraces Compared to uncultivated: thicker A, lower bulk density, higher organic carbon, higher N and P; • Impressive management suggests a substantial body of soil knowledge •

FAO/UNESCO • International system, adopted for purposes of creating a global map • Has been replaced by World Reference Base • Uses some classes from other systems

USDA Soil Taxonomy system • Seventh Approximation • Originally 10 Great Orders Have added two more (Andisols, Gelisols) • Many include another order “ Anthrosols” • • Hierarchical system

ORDER SUBORDER GREAT GROUP SUBGROUP FAMILY SERIES SUBORDER

Hierarchical categories • Order • Alfisol • Suborder • Udalfs • Great group • Hapludalfs • Subgroup • Typic hapludalfs • Family • Fine, loamy, mixed, superactive, frigid • Series • Nebish Fine-loamy, mixed, superactive, frigid Typic Hapludalfs

mean annual temp <8°C; >6°C range Nebish series Humid climate Fine-loamy, mixed, superactive, frigid Typic Hapludalfs particle size high CEC mixture of clay minerals Alfisol minimum horizon typical

Naytahwaush series Fine, smectitic, frigid Oxyaquic Hapludalfs Fine-textured, smectite clays, <8 C, water-saturated, minimum horizons, humid climate Alfisols

Fargo series • https: //soilseries. sc. egov. usda. gov/ Fine, smectitic, frigid Typic Epiaquerts