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En el centro de México se presentan cuerpos de agua continentales como el lago de Pátzcuaro, con importantes ecosistemas de humedal con diversas funciones ecológicas. Actualmente, la presión sobre los recursos naturales en las cuencas del país, aceleran la pérdida de humedales. El objetivo del presente estudio fue evaluar la reducción que ha tenido el lago de Pátzcuaro en una serie de tiempo de 42 años, de 1972 a 2014 como un indicador de la pérdida de los humedales lacustres y su relación con dos componentes del balance hídrico; precipitación y evapotranspiración. El estudio se realizó utilizando técnicas de percepción remota (PR), basadas en detección de objetos sobre imágenes de satélite. Una interpretación manual de la pérdida y ganancia de los humedales fue realizada considerando el año de 1972 como la línea base del estudio. Los resultados indican una reducción sostenida de la superficie del lago, pasando de 111.7 km2 a 79.82 km2, a una tasa negativa de 0.72 km2 año-1. La longitud de la costa se modificó de 90.14 km en el año de 1972 a 71.84 km lineales en el año de 2014. Los cambios prominentes encontrados fueron: la pérdida del humedal de Tzurumútaro a partir de los años de 1980, la fusión de las islas Jarácuaro y La Pastora y su ulterior unificación con el área terrestre circundante del lago.

Since soil CO2 flux is a key component of ecosystem carbon balance, quantifying its contribution to the ecosystem carbon flux and understanding the factors that underlie its temporal variation is crucial for a better comprehension of ecosystem carbon dynamics under climate change and for optimal ecosystem use and management. Our objectives were to quantify the contributions of total soil CO2 efflux (FS) to ecosystem respiration (RE) and heterotrophic soil CO2 efflux (FH) to FS in two chinampa ecosystems with different natural grass covers. We also aimed to identify the main environmental drivers of seasonal variability of these contributions. The CO2 fluxes were measured on each site about every 14 days from September 2008 to August 2009 in the Xochimilco Ecological Park in Mexico City using dark chamber techniques. For two studied sites, RE, FS and FH were estimated on average as 94.1 ± 8.5, 34.7 ± 3.5 and 16.5 ± 1.7 (± S.E.) mg C-CO2 m-2 h-1, respectively. On average over the study period and sites, the annual cumulative RE, FS and FH fluxes were 824 ± 74, 304 ± 31 and 145 ± 15 g C m-2 year, respectively. The RE, FS and FH varied between the winter and summer seasons; this variation was explained mostly by seasonal variations of soil temperature, soil water content and shoot plant biomass. Temperature sensitivity of CO2 fluxes depended on vegetation type and plant growth differences among the sites and decreased in the following order: RE > Rs > RH. The contribution of FS to RE and FH to FS for the two studied sites and period averaged about 38% and 50%, respectively regardless of the site vegetation type, but the degree of FS/RE and FH/FS variability depended on the differences in seasonal dynamics of plant cover. The contribution of FH to FS varied from 37% in summer to 73% in winter at the site without a seasonal shift in dominant plant species, but FH/FS was close to constant during the year at the site with a seasonal change in dominant plant species. During the cold period, the contribution of FH to FS increased following plant growth decrease. The linear regression analysis showed that plant biomass was the dominant factor controlling the seasonal variation of FH/FS ratios, whereas the plant biomass dynamic followed the dynamics of soil water content, water table depth, and soil temperature. Our results suggest that seasonal variation of soil contribution to total fluxes from the chinampa ecosystem is locally differentiated. These differences were related to differences in seasonal dynamics of cover productivity which has been associated with localization of soil water content. This finding has important implications for assessing the contribution of the chinampa ecosystem to the global carbon budget.

Seasonal changes of the soil CO2 concentration and the rate of CO2 fluxes emission from the soil formed on the sediments of the former Lake Texcoco, which occupied a significant part of the Mexico Valley until the mid-17th century, were studied. The soils (Fluvic Endogleyic Phaeozems) were characterized by a low CO2 fluxes rate, which is related to their high alkalinity. The mean values of soil respiration were 6.0–14.1 mg C/(m2 h) depending on vegetation type, which corresponds to 60–157 g C/(m2 yr). The contribution of plants to the CO2 fluxes insignificantly varied by seasons and depended on the species composition of vegetation. The soil CO2 concentration and soil respiration in eucalypt (Eucalyptus globulus Labill.) plantation were two times higher than those in the grass–subshrub area, the ground cover of which consisted of Distichlis spicata (L.) Greene and Suaeda nigra (Raf.) J.F. Macbr. species. This can be related to the significant volumes of gas production during the respiration of eucalypt roots and associated rhizosphere community. The contribution of the root systems of grass cover to the soil CO2 fluxes in eucalypt plantation slightly varied within the year and was equal to 24% on the average. In the grass–subshrub area, its value varied from 41% in the cold season to 60% in the warm season. The spatial variability of soil CO2 concentration and its flux rate to the atmosphere was due to the differences in plant species composition and hydrothermal conditions, and their temporal trend was closely related to the seasonal accumulation of plant biomass and soil temperature.

The aim of the study was to fill the gap in the knowledge on soils of montane cloud forest: until recently the soils formed in base-rich parent material under this forest type were insufficiently studied. We provided pedogenetic analysis of soils of two localities under montane cloud forest ecosystems in Sierra Gorda Mountains, Quiretaro state, Mexico. The site San Agustin had the annual rainfall of about 3000 mm and more diverse vegetative community. Soils formed in the debris and colluviums of silicate shales. The soils at this site were classified as Umbric Alisol (Cutanic, Humic). The pedogenesis of these soils included the stage of accumulation of polymerized organic matter and illuviation of clay rich in organic C, followed by the stage of progressing hydroconsolidation. Current clay illuviation occurs mainly under the consolidated fragipan-like layer. The site Yerba Buena had the annual rainfall of about 1000 mm and less diverse vegetation. Soils formed in a mixture of silicate shale and limestone-derived materials. The soils at this site were classified as Albic Fragic Luvisol (Calcaric, Cutanic). Initially these soils underwent the stage of leaching of bases and simultaneous hydroconsolidation that resulted in the formation of fragic horizon. Currently clay illuviation can be detected in these soils, but the process is not very active due to the compaction of the EBx and Btx horizons and the presence of residual calcite in the BC horizon. Both Alisols and Luvisols are seldom reported in montane cloud forest: they form mainly in base-rich parent material. For Luvisols under this forest type carbonate-rich parent material seems to be a pre-requisite for their formation.

The scarce information about soil carbon (C) storage in water-stressed ecosystems limits our understanding on soil contribution to the C cycle in arid zones. This study, performed in arid NW Mexico: (i) estimated soil capacity to store organic C (SOC) and inorganic C (SIC) linked to topography; (ii) determined the spatial distribution of regional SOC stocks; and (iii) analysed if different land-uses affect the C:N ratio. Contents of SOC from different landforms and land uses varied from

We studied testate amoebae (testates) in the soils of coniferous and deciduous forests and in the wetland and aquatic habitats of Mexico. In 141 samples we found 205 taxa identified to the species or intraspecies level and 68 testate amoebae, which could not be identified to the species level. The highest species diversity of testates was found in the soils of the tropical rainforest (126 species and intraspecific taxa, including spp.) and in tropical wetlands (144 species and intraspecific taxa, including spp.). The study documented testate amoebae with a limited geographical distribution (genera Centropyxis, Cornuapyxis, Ellipsopyxis, Hoogenraadia, Planhoogenraadia, Apolimia, Certesella, Apodera, and Alocodera). We found that testate amoebae in the soils of Mexico had a high level of polymorphism and individual variability. We discuss the value of soil testate amoebae for defining biogeographical regions of Mexico.

In montane cloud forests (MCF), the main soil organic carbon (SOC) pool is believed to be constituted by organic debris accumulated on soil surface and, to a lesser extent, by the organic fraction associated with the mineral matrix. The vertical distribution of SOC within soil has strong implications on the composition, stabilization and turnover of the soil organic matter (SOM). In ecosystems like MCF, where the climatic and edaphic conditions varied with altitude, the SOM accumulation and stabilization mechanisms possibly respond to these changes. For that reason, we studied the vertical distribution, accumulation and chemical composition of SOM in five montane cloud forest communities located between 1,500 and 2,500 m a.s.l. Two main SOC accumulation patterns were found: one at 1,500, 1,950 and 2,400 m a.s.l., with SOC content gradually decreasing with depth (cumulative); and another at 2,050 and 2,500 m a.s.l. where SOC had a strong maximum in the surface horizon and a less pronounced increase the spodic horizon (eluviation–illuviation pattern). The total SOC pool in soil decreased in inverse relation to altitude from 227 C ha−1 at 1,500 m a.s.l. down to 143 mg C ha−1 at 2,500 m a.s.l. About 40–60 % of total SOC content corresponded to the surficial organic horizon. The chemical fractionation of the SOM denoted in general predominance of the fulvic acid fraction, and high content of humin and humic acid fractions. We considered that the main SOC vertical distribution processes were related to the raw humus accumulation, decomposition in situ, podzolization in the eluviation–illuviation pattern soils mainly.

The paper gives an analysis of the pattern of soil cover of the Sierra Madre del Sur, one of the most complex physiographic regions of Mexico. It presents the results of the study of four latitudinal traverses across the region. We show that the distribution of soils in the Sierra Madre del Sur is associated with major climatic gradients, namely by vertical bioclimatic zonality in the mountains and by the effect of mountain shadow. Altitudinal distribution of soil-bioclimatic belts is complex due to non-uniform gradients of temperature and rainfall, and varies with the configuration of the mountain range. The distribution of soils is associated with the erosion and accumulation rates both on mountain slopes and in river valleys. The abundance of poorly developed soils in (semi)arid areas was ascribed to high erosion rate rather than to low pedogenetic potential. The formation of soil mosaic at a larger scale might be ascribed to the complex net of gully erosion and to the system of seismically triggered landslides of various ages. In the valleys, the distribution of soils depends upon the dynamics of sedimentation and erosion, which eventually exposes paleosols. Red-colored clayey sediments are remains of ancient weathering and pedogenesis. Their distribution is associated mainly with the intensity of recent slope processes. The soil cover pattern of the Sierra Madre del Sur cannot be explained by simplified schemes of bioclimatic zonality. The soil ranges can be explained by the distribution of climates, lithology, complex geological history of the region, and recent geomorphological processes.

The objective of this work was to compare the oribatid mite and springtail communities in three plots with different soil use - Coffee (CP), secondary vegetation or fallow fields (acahual, A) and a cloud mountain forest (CMF) - within a coffee plantation located in Santa Maria Huatulco, Oaxaca State, Mexico. In each plot 20 samples (10 of soil, 10 of litter) were taken and processed in Berlese funnels. The extracted fauna was preserved in 70% ethanol. A total of 3,031 oribatid mites belonging to 33 species, and 1,177 specimens of springtails belonging to 43 species, were collected. The number of species recorded was: 27 at CP (14 oribatids; 13 springtails), 44 at A (19 oribatids; 25 springtails) and 62 at CMF (32 for each group). A total of 26 oribatid and 27 springtail species was found in the soil, and 25 oribatid and 32 springtail species were found in the litter. The most abundant species were the oribatids Rostroztes foveolatus (Haplozetidae), Tectocepheus sp. (Tecocepheidae), Karenella sp. (Oppidae), Atropacarus (Hoplophorella) cf. fonseciai (Phthiracaridae), Epilohmannia pallida americana (Epilohmannidae), and the springtails Ceratophysella cf. gibbosa (Hypogastruridae), Mesaphorura sp. (Tullbergidae) and Proisotoma cf. minuta (Isotomidae). Fourteen families and 18 species of Oribatida species and 5 families and 34 species of Collembola were recorded for the first time for the State.

This study was done in San Salvador and El Bondho, Mezquital valley, Hidalgo State, Mexico, with the aim of comparing the Collembola community from two plots with the same edaphic classification: San Salvador is irrigated with waste water (residual water) from Mexico City, and El Bondho, is watered from a well (sweet water). A total of 5967 Collembola from 31 species were obtained of which 19 are new records for Hidalgo State; 4833 specimens were from San Salvador and 1134 from El Bondho. Their species richness was 29 and 19, respectively. Dominant species both in abundance and frequency were Proisotoma minuta, Cryptopygus thermophilus, Xenylla grisea and Hypogastrura essa at San Salvador. Diversity and evenness were higher there than in El Bondho; in addition the species richness was lower than at San Salvador; mainly due to the dominant species. Similarity coefficient shows a disturbance in the composition of the Collembola communities, with only 70% of similarity among both plots. The irrigation type affects the density of some species like X. grisea, Folsomides parvulus, Cryptopygus ca. benhami, Pseudosinella octopunctata and C. thermophilus and composition in both plots while Lepidocyrtus violaceus, Pseudosinella violenta and Sphaeridia serrata are affected by irrigation kind and sampling date. Soil properties, such pH, EC, OM and exchangeable contents of cations (Mg2+, Na+) appear to affect the composition and abundance of the Collembola communities.

The Chinampas are important historically and represent a special agroecosystem that has been sustainable for many years. However, their agricultural potential has currently decreased mainly because of irrigation with waste water from Mexico City, leading to progressive salinity and alkalinity problems and the subsequent general alteration on the agroecosystem. Chemical composition of the main groups of lipid molecules in anthropogenic organic soil from Xochimilco and Tlahuac Municipalities (Mexico) were investigated. The analysis performed included physicochemical characteristics of the soil and the distribution analysis of free alkanes and fatty acids. The successive accumulation stages of organic materials in these anthropogenic organic soils represent a source of irregular distribution in organic carbon, likewise the concentration of lipid extracts differed noticeably with depth. There is a vertical variability, where hydromorphic environment has played a key role in this variability. The major compounds identified in the soil lipid extracts by gas chromatography-mass spectrometry include series of linear and satured alkanes, fatty acids, as well as individual components such as sterols and hopanes. Most of the lipid components in these soil seem to have a biogenic origin (higher plants and microorganism biomass).

The chinampas agriculture is a traditional land use practice in the Valley of Mexico since Pre-Hispanic time. The chinampas soils were constructed by excavation of lake sediments that resulted in the creation of a system of islands separated by channels. The agricultural productivity of these artificial soils was high; also the land use practices included forestry, fish breeding and hunting. Nowadays, the chinampas soils are affected by excessive salinity. We studied 10 representative soil profiles in the chinampas zone of Mexico City in order to characterize their properties and origin, to provide their classification, and to evaluate soil salinization, vertical distribution of the salts and their chemical composition. The soils are characterized by a layered structure, uniform dark grey colour, irregular vertical distribution of organic carbon and clay, and high percentage of carbon. Some soils show an increase in organic matter with depth, and other profiles have maximum organic matter content in the surficial layers and in the subsoil. The dynamics of sedimentation resulted in the decrease in organic matter in the upper layers of lacustrine sediments, because of recent increase in erosion rate and consequent increase in the proportion of mineral particles in the sediments. Most probably high organic matter content in surficial layers of some soils is due to excavation and accumulation of organic-rich subsoil material in the course of digging the channels. The concentration of soluble salts in superficial horizons, expressed as electric conductivity, varies in a wide range from 5 to almost 50 dS·m-1. The salts concentrate mainly in the superficial layers of soils. The abundance of the cations of soluble salts is Na+>Mg2+>Ca2+>K+ and that of the anions is SO42->Cl->HCO3->CO32-. The alkaline reaction of soils is caused by exchangeable Na rather than by free sodium carbonates. The restoration of chinampas requires a complex approach, combining soil, water and ecosystems remediation.La agricultura de chinampas es una práctica tradicional de uso del suelo en el Valle de México desde la época prehispánica. Los suelos de chinampas fueron construidas por la excavación de sedimentos del lago que resultó en la creación de un sistema de islas separadas por canales. La productividad agrícola de estos suelos artificiales fue alta; también las prácticas de uso del suelo incluyeron la silvicultura, la pesca y la caza. Actualmente, los suelos de chinampas están afectados por una salinidad excesiva. Se estudiaron 10 perfiles de suelos representativos de la zona de chinampas de la Ciudad de México con el objeto de caracterizar sus propiedades y origen, obtener su clasificación, evaluar la salinización del suelo, la distribución vertical de las sales y su composición química. Los suelos se caracterizan por presentar una estructura en capas, de color gris oscuro uniforme, y una irregular distribución vertical de carbono orgánico y arcilla. Algunos suelos muestran un aumento de la materia orgánica con la profundidad y otros perfiles presentan un contenido alto de esta en las capas superficiales y en el subsuelo. La dinámica de la sedimentación como resultado de la disminución de la materia orgánica en las capas superiores de los sedimentos lacustres se debe al aumento reciente en la tasa de erosión y al consiguiente aumento en la proporción de partículas minerales en los sedimentos. El alto contenido de materia orgánica en las capas superficiales de algunos suelos se debe a la acumulación de material del subsuelo rico en materia orgánica obtenida del fondo de los canales. La concentración de sales solubles en los horizontes superficiales, expresada como conductividad eléctrica, varía de 5 a 50 dS?m-1. Las sales se concentran principalmente en las capas superficiales de los suelos. La abundancia de los cationes de las sales solubles es Na+>Mg2+>Ca2+>K+ y la de los aniones es SO42->Cl->HCO3->CO32-. La reacción alcalina de los suelos se debe al Na+ intercambiable más que por carbonatos de sodio libres. La recuperación de las chinampas requiere de un planteamiento complejo, con la combinación del suelo, agua y de la recuperación de los ecosistemas.A agricultura de Chinampas é uma prática tradicional do uso do solo no Vale do México, desde tempos pré-hispânicos. Os solos de Chinampas foram construídos em consequência da escavação de sedimentos lacustres, resultando na criação de um sistema de ilhas separadas por canais. A produtividade agrícola desses solos artificiais era elevada bem como as práticas de uso do solo incluindo pesca, silvicultura e caça. Estes solos caracterizam-se por uma estrutura em camadas, de cor cinza escuro uniforme, e uma distribuição vertical irregular de carbono orgânico e argila. Alguns solos apresentam um aumento da matéria orgânica com a profundidade enquanto outros apresentam perfis com um alto teor de matéria orgânica nas camadas superficiais e subsolo. A dinâmica de sedimentação como resultado da diminuição de matéria orgânica nas camadas superiores dos sedimentos lacustres deve-se ao recente aumento da taxa de erosão e ao consequente aumento da proporção de partículas minerais nos sedimentos. Este alto teor de matéria orgânica nas camadas superficiais de alguns solos deve-se à acumulação de material do subsolo rico em matéria orgânica com origem no fundo dos canais. A concentração de sais solúveis nos horizontes de superfície, expressa pela condutividade eléctrica varia de 5-50 dS m-1. Os sais concentram-se principalmente nas camadas superficiais do solo. A abundância de catiões de sais solúveis segue a seguinte ordem: Na+> Mg2+> Ca2+> K+ e a dos aniões a ordem: SO42-> Cl-> HCO3-> CO32-. A reacção alcalina dos solos deve-se sobretudo ao sódio de troca e não ao carbonato de sódio de troca livre. A recuperação das chinampas exige uma abordagem complexa, que combina a remediação do solo, água e ecossistemas.

"El agua subterránea es importante en el contexto económico del estado de Puebla, en donde se ubica la mayor proporción del área de estudio, ya que condiciona la factibilidad de incrementar su desarrollo económico. El 80% del agua subterránea se emplea en la agricultura. La mayor proporción del agua disponible, en el estado, se encuentra en la Cuenca Oriental. La extracción en la cuenca se ha incrementado en los últimos años al incorporar nuevas áreas a la agricultura de riego. La agricultura, en la cuenca, está condicionada por las características y propiedades físicas del suelo y la calidad del agua. En suelos de alta permeabilidad, de textura gruesa, se usa el riego por aspersión y en suelos de alta impermeabilidad, de textura fina, el riego por inundación, usando melgas y surcos. Al recurrir a estos métodos de riego, la calidad química y agronómica del agua se convierte en un factor importante, por los efectos que puede tener sobre el suelo y los cultivos. Se usaron índices como: carbonato de sodio residual, índice de saturación y relación de adsorción de sodio corregida. Estos índices son mejores parámetros para la evaluación de las aguas bicarbonatadas. El valor medio del pH fue de 8.7. La concentración media de 492.75 mg L-1 y el carácter sódico bicarbonatado de las aguas subterráneas, de la cuenca, es definida por los materiales de origen volcánico con las que tienen contacto. Las aguas de los pozos profundos, son de baja concentración iónica, con una media de 244.37 mg L-1, una media de 1.80 molc Na+ L-1 y 2.16 mmolc HCO3 - L-1. Las aguas del estrato superior, correspondientes a las capas freáticas, son de alta concentración iónica, con una media de 865.31 mg L-1, una media de 7.15 mmolc Na+ L-1 y 6.92 mmolc HCO3 - L-1."

"Three soils were studied at a coffee growing farm El Nueve, Sierra Madre del Sur, Oaxaca, Mexico: Skeletic Phaeozem, Ferralic Umbrisol, and Epileptic Calcaric Phaeozem. The formation of these soils was regulated by the origin of parent material (Epileptic Calcaric Phaeozem formed on limestone), and by the age of the exposed surface (Skeletic Phaeozem was formed on the slope of a recently formed V-shaped valley, and Ferralic Umbrisol - on an ancient weatheringcrust, derived from the same gneiss). The three soils differed in their acidity, organic matter composition, clay mineralogical composition, and exchangeable complex characteristics. Ferralic Umbrisol differed from the two other soils by its lower cation exchange capacity and base saturation, mainly kaolinitic clay mineralogical composition, heavier texture, and higher acidity. Skeletic Phaeozem had coarser texture, higher rock fragments content, and high percentage of light organic matter. Epileptic Calcaric Phaeozem had the highest base saturation, a combination of clayey texture with abundant rock fragments, and humic acids as the main component of soil humic substances. The diversity of soils of tropical mountainous areas is high due to the diversity of parent materials and the age of exposed surfaces."

"En las fracciones húmicas de tres suelos de chinampa, dos no salinos y uno salino sódico (conductividad eléctrica 23 dS m-1), se evaluaron la distribución de carbono y el contenido total de metales pesados con la finalidad de conocer el grado de polimerización y evolución del humus para promover estrategias de conservación y recuperación de la zona. Con base en profundidad, color, características edáficas y medio circundante dentro del perfil, se estudiaron tres horizontes: el superficial (Aht), el álbico (Aab) y el profundo (Atr O Htr). Los porcentajes de carbono en las sustancias húmicas [ácidos húmicos (AH), ácidos fúlvicos (AF) y huminas (H1, H2, H3)], los contenidos totales de metales pesados (Al, Co, Fe, Cr, Cd, Ni, Zn, Cu), los análisis electroforéticos en AH y la salinidad de cada uno de los suelos definieron que la evolución del humus depende más de las características antrópicas (manejo agrícola y adición de materiales orgánicos) y edáficas (contenido de carbono, metales totales y arcilla) que de las condiciones ambientales (nivel freático-humedad) y contenido de sales. La evolución del humus, expresada en la relación: Horizonte superficial (Aht) = horizonte profundo (Htr o Atr) > horizonte álbico (Aab) se relacionó con la profundidad y con las características edáficas de cada horizonte del perfil."

"Uno de los problemas que preocupa al hombre actual es el aprovechamiento, manejo y destino de los subproductos de los recursos naturales que emplean en su quehacer diario. Por la naturaleza biológica de la mayoría de ellos, se hace necesario conocer a profundidad los procesos de biotransformación enzimática, lo cual permitiría darle un manejo y destino más apropiados. El presente trabajo reporta los resultados de un estudio de la dinámica enzimática del proceso de compostaje y vermicompostaje (compostaje con incorporación de la lombriz Eisenia andrei) de paja de avena, molida y picada. Veintitrés, 46, 69, 92, 115 y 148 días después de adicionadas las lombrices, se tomaron muestras en todos los tratamientos para medir la actividad de las enzimas: proteasa, amidasa, ureasa y nitrogenasa. La actividad de esas enzimas fue mayor en los tratamientos con lombrices que en los que no se aplicó el anélido. La actividad enzimática disminuyó en relación directa con la madurez de la composta. La paja molida aceleró los procesos enzimáticos. El conocimiento adquirido acerca de la dinámica enzimática del proceso de compostaje puede emplearse para manejar de manera más sostenible y aún acelerar el proceso de biotransformación de los residuos de la paja y, quizás, de otros residuos similares, mediante la adición de enzimas en los tiempos apropiados."

El presente trabajo se llevó a cabo para evaluar durante tres ciclos de cultivo, dos sistemas de labranza, y ocho tratamientos de fertilización nitrogenada y fosfatada sobre el rendimiento de maíz (Zea mays L.), variación en pH, materia orgánica y población de lombrices en un suelo franco arenoso de Chapingo, México. En el experimento se utilizó un diseño en parcelas divididas, en donde las parcelas grandes correspondieron a los Sistemas de Labranza (labranza de conservación con cobertura de veza, labranza de conservación con cobertura de cebada, labranza tradicional con raíz de veza y labranza tradicional con raíz de cebada). Dentro de cada una de las parcelas grandes se distribuyeron al azar los ocho tratamientos de fertilización, que correspondieron a las parcelas chicas. Los cultivos de cobertura se sembraron en otoño y el maíz en primavera. Después de cada ciclo de cultivo de maíz se evaluó su rendimiento y se tomaron muestras de suelo a dos profundidades (de 0 a 5 cm y de 5 a 30 cm) en cada tratamiento, para los análisis de pH y materia orgánica; en el segundo ciclo de cultivo se cuantificó la población de lombrices. El rendimiento de maíz fue mayor en el sistema de labranza de conservación con cobertura de veza (3.19 t ha-1) comparada con cobertura de cebada (2.51 t ha-1). La fertilización nitrogenada aumentó el rendimiento de maíz de 2.39 t ha-1 con 0 kg N a 3.09 t ha-1 con 80 kg N ha-1, cuyos valores fueron estadísticamente diferentes; con la fertilización fosfatada se observó un ligero incremento de rendimiento no significativo. El pH del suelo se abatió en labranza de conservación con cobertura de veza (de 7.2 a 6.6 de 0 a 5 cm y de 7.2 a 6.9 de 5 a 30 cm de profundidad). En labranza tradicional con raíz de cebada el abatimiento fue ligero (7.4 a 7.1 de 0 a 5 cm y de 7.2 a 7.1 de 5 a 30 cm). El contenido de materia orgánica se incrementó de 1.19 % a 2.55 % de 0 a 5 cm y de 0.99 % a 1.31 % de 5 a 30 cm de profundidad en labranza de conservación con cobertura de veza. Los incrementos más bajos se observaron en labranza tradicional con raíz de cebada (de 1.19 % a 1.40 % de 0 a 5 cm y de 0.99 % a 1.43 % de 5 a 30 cm de profundidad). La población de lombrices aumentó significativamente en los tratamientos con cobertura de veza en labranza de conservación (268 lombrices m-2), comparada con labranza de conservación con cobertura de cebada (146 lombrices m-2). En la labranza tradicional con raíz de veza se cuantificaron 64 lombrices m-2 y en la labranza tradicional con raíz de cebada 48 lombrices m-2. La cobertura de veza favoreció un mayor rendimiento de maíz, abatió el pH del suelo y aumentó el contenido de materia orgánica y la población de lombrices.