The Wondrous Soils of Central and South America

The Wondrous Soils of Central and South America Zac Davies, Phil Garcia, Meghan Mariani, & Michelle Trogdon

Introduction • Central America • Soil Orders • Factors Influencing Formation • Guatemala • Brazil and the Amazon River Basin • Soil Orders • Slash and Burn Effects on soil • Logging Effects on Soil • Andean Soils • High Altitude Soils • Soil Profiles • Argentinean Soils • Soil Orders

Soils of Central America Soil Orders Factors influencing formation Soils of Guatemala

Soil Orders • Entisols- weakly developed coastal sandy sediments • Inceptisols- weakly developed horizons • Andisols- volcanic origins rich in organics • Vertisols- swell and shrink due to water content • Mollisols- fertile A horizon • Alfisols*- clays and oxides, retain nutrients and moisture • Ultisols*- clays and oxides, leached of organics

Factors Influencing Formation • Climate- tropical, humid • regular rainfall • volcanic/seismic activity • hurricanes • Topography • Resource conservation • rainforest • Anthropogenic • agriculture “Banana Republics” • archaeological • tourism

Guatemala • Demographics • population ~12. 7 million • land ~100, 000 km 2 • Agriculture • Sugar, coffee, bananas, corn, and beans • CAFTA • Conservation • contour planting, erosion barriers • mixed crops

Biodiversity

Agriculture • Environmental issues • deforestation, Peten • soil erosion • water pollution • 13% arable land, 5. 6% permanently cultivated • 1, 300 km 2 of irrigated land • protected rainforest, sustainable agriculture, topo planting, organic, biodiverse, shade-grown, bird friendly

Brazil and the Amazon River Basin

Oxisol • Support Brazilian savannahs • The most highly weathered soils, up to 20 m • There most distinct feature is a deep oxic horizon containing lots of clay and iron/aluminum oxides • Low nutrient availability and moderately acid

Ultisol • Created in humid subtropical-tropical climates, including forests and savannas • A possible carbon sink • Formed from clay mineral weathering • Contain an acidic B horizon • Contains very few cations • Usually red or yellow in color

Slash and Burn �Only a quick fix for agriculture, it frees up lots of plant available N and P � 2 -3 years of sustainable agriculture �Increased erosion and soil degradation �Only useful to small populations with large areas of land shifting cultivations � 1/3 of total soil organic carbon is lost in the transformation from primary forest to pasture �About 1/5 of total N is lost in transformation from forest to pasture

Logging Selective logging was considered environmentally friendly but has proved to be nearly as destructive as other methods Removing tree canopies leads to a dry fire prone undergrowth and forest floor Logged Soils showed an increase in N 2 O and NO emissions compared to primary forest Forest soils are normally a CH 4 sink while logged soils emit CH 4

High Altitude Soils: Andes Mt. Range • In general soils are relatively young • Thin, poor quality soils are often found • Steep gradient creates a highly erosive environment from wind and water • Incas used the steep slopes for agriculture/irrigation through terracing • Main soils found: • Gelisols • Andisols

Gelisols � Found in high latitudes and altitudes/ very cold regions � In this case mainly in the S. range between Chile and Argentina • Highest peak: Aconcagua- 22, 841 ft. � Has distinct permafrost layer and often frost churning takes place � Black/ Dark Brown in color because O. M. high in carbon accumulates above permafrost layer � Cold temp and annual freezing make for slow soil formation/not much of a profile and no B horizon � Not for use in agriculture because most nutrients tend to be leached out � Frozen conditions make then sensitive to human impacts � Gelid = very cold

Andisols • Found throughout the whole range, and high in elevation, but not as high as the gelisols • Also a relatively young soil • Mainly composed of thick ash over laying glacial deposits, found near or downwind from the source of the ash (volcanoes) • Creates a unique soil cover for native tree species • Dominated by Allophane and Al-Humic complexes • depending on the location, can be naturally fertile and used in agricultural practices • Ando = Black soils

Soils of Argentina 4 major soil orders and % coverage in Argentina 22% 7. 4% 31% 20% Argentina

Alfisol Al=Aluminum / fi=ferric Description: -too thin/low in organic matter for a mollic epipedon -precipitation causes clay, aluminum and iron to accumulate in the B horizon Where: -widely represented in the Chaco-Pampean plains typified by grasslands and savannas -usually occupy flat or concave areas between higher parts of the landscape. Uses and Results: -utilized for cattle grazing /water and sodium tolerant pastures

Mollisol Description: � Dark-organic rich surface A horizon � formed by debris of weathered rocks with significant amounts of volcanic glass due to past eruptions of Andean volcanoes. � rich in weatherable minerals with conspicuous amounts of calcium, potassium, phosphorus of volcanic origin � presence of a Ca. CO 3 enriched horizon that occupies wide areas of mollisols in humid climate Where: � occupy much of. Chaco-Pampean plains � dominant soil with the best aptitude for agriculture � High precipitation due to moist Atlantic air streams create agriculturally suitable soil Uses and Results: � Intensive agriculture has resulted in a hardpan horizon in many areas

Aridisol Description: � Low OM and Nitrogen but high phosphorus � Rain shadow of the Andes Where: � widely distributed in low precipitation areas of Argentina covering 60% of the country, mostly in Patagonia � Dry Patagonian air causes highly un arable soil susceptible to desertification Uses and Results: � subsistence farming populations frequently perform unsuitable tillage, irrigation or overgrazing � preventing desertification is and has been carried out from different government institutions � Crop rotation and No-till methods

Entisol Description: - Little development of soil horizons - Receive new deposits of alluvium at frequent intervals Where: � widely distributed in the arid and semiarid areas, occupying large parts of Patagonia and the NW of the country � common along the extensive coasts Uses and Results: � utilized in this case for tree plantations and horticultural crops.

Summary • Central America • Alfisols and Ultisols • Tropical climate • Sustainable farming • Brazil and the Amazon River Basin • Oxisols and Ultisols • Slash and Burn temporary solution • Logging, new methods need to be found • Andean Soils • Gelisols and Andisols • Limited agricultural use • Argentinean Soils • Mollisols and Entisols • Desertification from poor agricultural management

References Chemonics, CQI, Anacafé, Ono Farms, Elan Organic Coffees, 2004. Conservacion de suelos. Sustainable Harvest Seminario de Caficultura Orgánica Chemonics, CQI, Anacafé, Ono Farms, Elan Organic Coffees, 2004. La Produccion de café organico: Sostenibilidad para los productores de Centroamerica. Sustainable Harvest Seminario de Caficultura Orgánica www. cia. gov/library/publications/the-worldfactbook/index. html www. diamondorganics. com/images/189_coffee 300. jpg