Soil fertility differences across a land-use intensification gradient in the highlands of Chiapas,Mexico |
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Authors: | José David Álvarez-Solís Peter M Rosset Blanca Mayela Díaz-Hernández Héctor Plascencia-Vargas Robert A Rice |
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Institution: | (1) Departamento de Agroecología, División de Sistemas de Producción Alternativos, El Colegio de la Frontera Sur, Apartado Postal 63, San Cristóbal de Las Casas, Chiapas, Mexico;(2) Institute for Food and Development Policy, 398 60th Street, Oakland, CA 94618, USA;(3) Smithsonian Institution, Washington, DC 20008, USA |
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Abstract: | In the highlands of Chiapas, southern Mexico, soil texture and soil chemical properties were measured in 70 agricultural fields
covering a range of slope positions and managements. Fields represented four corn cropping systems: long fallow, short fallow,
pasture–cultivation rotation, and annual continuous cultivation, in addition to fallow at rest (forest, shrubland, and pastures).
Fields were located in four slope positions (upper, middle, and lower slopes, and doline floor) in a karst landscape developed
on limestone with additions of acid volcanic ashes. Distribution of clays and sands were related to the toposequence and the
percentage of clay fraction increased from upper slope to doline floor. Sand presented a reverse pattern. Some soil chemical
properties also vary in a characteristic way along the toposequence. Exchangeable Ca2+ and Mg2+ effective cation exchange capacity (ECEC) and pH were higher in the doline floor than in the other slope positions. Soil
organic matter and total N contents were 30.4 and 35.2% higher under long fallow than under annual continuous cultivation.
Soil Olsen P was greater under cultivation than under fallow (irrespective of the cropping system), with the highest values
under annual continuous cultivation (16.2±8.3 mg kg−1) and the lowest in the forest (5.3±2.5 mg kg−1). Exchangeable K+ was 74 and 51% higher in cultivated plots of the long and the short fallow than under forest and shrubland, respectively.
Exchangeable Ca2+ and Mg2+ and ECEC did not vary significantly among the cropping systems. Inputs of basic cations through burning of tree and shrub
vegetation increased the soil pH. These results indicate that land use intensification is leading to a decline in soil organic
matter and total N, whereas Olsen P increased with intensification due to the continuous application of P fertilizers and
sheep manure as soil conditioners in intensively cultivated fields. |
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Keywords: | Soil fertility Land-use intensification Soil organic matter Phosphorus Zea mays |
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