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INSTITUTE OT' SOCIAL AKTHROPOLOGY — PUBLICATION NO. 1 1 



fications are: cultivated lands according to water 

 content (jugo, riego, temporal), noncultivated 

 lands according to use and vegetation (pastal, 

 monte), arable soils according to productivity 

 (1", 2*, 3", 4*), soils according to color (charanda 

 or colorada, caf6, amarilla or tupura, negra or 

 prieta), and soils according to texture (arcillosa, 

 migajosa, arenosa, pedregosa). None of these 

 classifications is scientific or gives an adequate 

 idea of the contents and lacks of the soils. 



Locally it is estimated that about 32 percent of 

 the municipality is woodland and brushland 

 {monte), 27 percent scabland and miscellaneous 

 nonusable, 21 percent pasture land ijpastal), and 

 20 percent arable. The arable land (tierra de 

 labor) is composed of temporal (about 88.65 per- 

 cent), humedad (nearly 10.85 percent), and less 

 than one-half of 1 percent of riego. The tierras de 

 humedad are soils in which the subsoU moisture is 

 maintained for a long time after the rainy season 

 by infiltration from exterior sources. Most of 

 such soil areas are near springs, in the lowlands 

 near the lake, and in some of the joyas or depres- 

 sions of the uplands. Most of the riego and 

 humedad soils are reddish to grayish sandy loams 

 and silts among which the sUty alluvial and aeolian 

 polvillas are most important. Every rainy season 

 large quantities of extremely fine reddish silt are 

 spread over the lake plains and are deposited in 

 the lake. This silt derives from the erosion of the 

 volcanic soils and rocks of the area, and is 

 moderately rich in organic matter. The tierras 

 de primera clase embrace nearly all of the riego 

 and humedad soils, and most of the temporal soils 

 of the higher lake plain, the lower, gentler slopes 

 around Quiroga, and the bottoms and lower slopes 

 of the upland valleys. The remaining grades of 

 temporal (second, third, fourth) represent decreased 

 productivity which is a function of excessive use 

 and of steeper slopes. Most of the temporal soils 

 grade from tierras tepetatosas and arcillas in de- 

 nuded areas, through clay loams, to sandy loams. 

 The reddish colored clay loams predominate. 



In terms of scientific classification, the soils of 

 the Quiroga area are predominantly subtropical 

 and temperate humid (wet-dry) climate (Cwbg of 

 Koeppen; B (p) B'2 (a') of Contreras Arias- 

 Thornthwaite) pcdalfers, with practically no pedo- 

 cals, and only a thin band of hydromorphs and 

 alluviums along the lake. The deep, friable soils 

 developed in situ from the basic volcanic rocks 



seem to fall within the group of laterized soils. 

 These lateritic soils are chiefly reddish-brown clays 

 and loams with some development of yellow- 

 brown and yellow soils. In the forested highlands 

 the yellow, brown, and gray-brown soils developed 

 under the pines and in the oak-pine-madrono 

 association grade from lateritic into podzolic soils. 

 Northeast of Quiroga, and outside of the Patz- 

 cuaro drainage basin, there is some development 

 of reddish-brown prairie soils — as in the area just 

 beyond the Cerro Hueco. In a few undrauied 

 depressions and immediately along the lake shore 

 are gleized soils approaching meadow (Wiesen- 

 boden) and half-bog types. There are no im- 

 portant areas of halomorphic soUs, since practically 

 all of the area is well drained. The alluvial soils 

 have been mentioned previously. 



Table of Quiroga soils 

 Zonal: 



Pedalf ers : 



Lateritic: 



Reddish-brown Suelos (arcillas) rojos. 



clays. 

 Reddish-brown Migajones rojos and 



loams. caf(5-obscuros. 



Y e 1 1 o w - b r o w n Suelos caf 6-amarillantes. 

 soils. 



Yellow soils Suelos amarillos. 



Brown forest soils. Suelos caf6 forestales. 

 Podzolic: 



Gray-brown forest Suelos caf^-parduscos de 



soils. bosque. 



Yellow forest soils. Suelos amarillos fores- 

 tales. 

 Pedocals: 



Reddish-brown prairie. Suelos de pradera. 

 Intrazonal: 



Hydromorphic: 



Meadow and half-bog 

 gleis. 

 Azonal: 



Alluvial silts AUuviones, limos, polvil- 

 las. 



Most of the soils have well-developed profiles. 

 The normal sequence is an A horizon of loam, a B 

 horizon of soft clay, a C horizon of hard, imperme- 

 able clay or tepetate, and the underlying bedrock. 

 A hardpan or piso de arado is commonly encoun- 

 tered in the lowland fields, owing to generations 

 of cultivation to the same depth with iron-tipped 

 wooden plows. Because of the extreme amount 

 of sheetwash and gullying, large areas are lacking 

 the A horizon, and considerable areas have surfaces 

 of the C horizon or tepetate. Furthermore, al- 



