Estructura Del Suelo

The aim of this study was to evaluate the effect of animal trampling on some hydrophysical properties of a typical Hapludol implanted with «Triticosecale Wittmack», by means of a rotational grazing system (7 days of occupation and 42 days off) with four stocking rates corresponding to forage allowances of 2, 4, 6 and 8 kg dry matter/100 kg of live animal weight per day, under two soil moisture contents: dry soil, with 11% and moist soil, with 18% water content. The results were compared to an ungrazed reference system. The study was conducted at the experimental station of the Universidad Nacional de Rio Cuarto, southwestern Córdoba province, Argentina, under an experimental design in randomized blocks with a split plot arrangement. The parameters assessed were: bulk density (BD), relative compaction (RC), total porosity (TP) at 0-5 cm and 5-10 cm depths, and initial and final infiltration rate (IIR and FIR, respectively). BD showed an increase (p <0.05) at the 0-10 cm depth, whi...

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Regeneration of the soil structure and its effect on water infiltration. Assessment of soil amendments applied on Argiudols under no-tillage Surface soil structure of silty soils under no-till is characterized by the development of a P structure that restricts water infiltration. Cultural practices can be used to modify soil structure in the short term, e.g. tillage practices, and in the medium-long term, e.g. crop sequences. Poultry litter (C) and gypsum (Y) are available soil amendments in Entre Ríos Province, for short-term modification of soil structure. The objective of this study is to advance in the understanding of regeneration of surface soil structure of agricultural soils under no-till. Changes in soil structure and associated soil properties were evaluated in long-term field experiments through cultural profile technique and rainfall simulations in the field, and soil bulk density (Dap), aggregate stability (AE), soil pore distribution, among others, evaluations in the laboratory. Long-term field experiments exhibited contrasting soil structure in the surface layer among tillage practices. No-till treatments were characterized by the presence of soil P structure between 5 to 10 cm deep, that was greater thickness for only soybean (Sj-Sj) crop sequence. No-till plots were also characterized by increased runoff (e.g. reduced water infiltration) compared to vertical tillage. The addition of soil amendments suggested potential for restoring soil structure under no-till. Addition of C increased the proportion of Γ structure and decreased P structure, due to promotion of soil biological activity. The increased Γ structure type with C addition was also associated to improved soil physical conditions (Dap, PT, PE and soil pore distribution). The addition of Y increased EA of Γ structure type. The results of this work contribute to explain the temporal evolution of P structure formation and its regeneration. The use of poultry litter and gypsum in no-till agricultural systems seem to be promising practices for optimizing crop production and minimizing environmental impact.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Regeneration of the soil structure and its effect on water infiltration. Assessment of soil amendments applied on Argiudols under no-tillage Surface soil structure of silty soils under no-till is characterized by the development of a P structure that restricts water infiltration. Cultural practices can be used to modify soil structure in the short term, e.g. tillage practices, and in the medium-long term, e.g. crop sequences. Poultry litter (C) and gypsum (Y) are available soil amendments in Entre Ríos Province, for short-term modification of soil structure. The objective of this study is to advance in the understanding of regeneration of surface soil structure of agricultural soils under no-till. Changes in soil structure and associated soil properties were evaluated in long-term field experiments through cultural profile technique and rainfall simulations in the field, and soil bulk density (Dap), aggregate stability (AE), soil pore distribution, among others, evaluations in the laboratory. Long-term field experiments exhibited contrasting soil structure in the surface layer among tillage practices. No-till treatments were characterized by the presence of soil P structure between 5 to 10 cm deep, that was greater thickness for only soybean (Sj-Sj) crop sequence. No-till plots were also characterized by increased runoff (e.g. reduced water infiltration) compared to vertical tillage. The addition of soil amendments suggested potential for restoring soil structure under no-till. Addition of C increased the proportion of Γ structure and decreased P structure, due to promotion of soil biological activity. The increased Γ structure type with C addition was also associated to improved soil physical conditions (Dap, PT, PE and soil pore distribution). The addition of Y increased EA of Γ structure type. The results of this work contribute to explain the temporal evolution of P structure formation and its regeneration. The use of poultry litter and gypsum in no-till agricultural systems seem to be promising practices for optimizing crop production and minimizing environmental impact.

The widespread degradation of the structure of silty soils under no till systems (NT) that has been observed in recent years is characterized by the presence of a platy structure (P) near the soil surface. Under these conditions, addition of organic and inorganic amendments could have beneficial effects on soil physical properties. We assessed structural regeneration following addition of amendments in an Argiudoll of Paraná, Argentina. Poultry litter (PL) and gypsum (G) were applied, providing an organic and inorganic amendment, respectively. Four treatments were tested: PL (7.5 Mg ha-1), G (3 Mg ha-1), the combination of PL+G (7.5+3 Mg ha-1), and control (T) with no amendment. Description and quantification of the structural state of the soil profile was made using a Visual Soil Evaluation method: "Le profil cultural". Aggregate stability, bulk density, total porosity, pore size distribution and soil shear strength for each soil structure and soil organic carbon (SOC) were determined at two depths. Twenty months after the amendment applications, both PL and PL+G treatments led to a significant increase of SOC in the upper 5 cm of soil. The proportion of Gamma (Γ) structure increased and P declined under PL and PL+G compared with G and T inn the A horizon. Treatments G and PL+G contributed to an increase in average diameter of aggregates in Γ only. The use of PL amendment alone or in combination with G could be a promising strategy to regenerate, in the short-term, the degraded soil structure under NT.

Regeneration of the soil structure and its effect on water infiltration. Assessment of soil amendments applied on Argiudols under no-tillage Surface soil structure of silty soils under no-till is characterized by the development of a P structure that restricts water infiltration. Cultural practices can be used to modify soil structure in the short term, e.g. tillage practices, and in the medium-long term, e.g. crop sequences. Poultry litter (C) and gypsum (Y) are available soil amendments in Entre Ríos Province, for short-term modification of soil structure. The objective of this study is to advance in the understanding of regeneration of surface soil structure of agricultural soils under no-till. Changes in soil structure and associated soil properties were evaluated in long-term field experiments through cultural profile technique and rainfall simulations in the field, and soil bulk density (Dap), aggregate stability (AE), soil pore distribution, among others, evaluations in the laboratory. Long-term field experiments exhibited contrasting soil structure in the surface layer among tillage practices. No-till treatments were characterized by the presence of soil P structure between 5 to 10 cm deep, that was greater thickness for only soybean (Sj-Sj) crop sequence. No-till plots were also characterized by increased runoff (e.g. reduced water infiltration) compared to vertical tillage. The addition of soil amendments suggested potential for restoring soil structure under no-till. Addition of C increased the proportion of Γ structure and decreased P structure, due to promotion of soil biological activity. The increased Γ structure type with C addition was also associated to improved soil physical conditions (Dap, PT, PE and soil pore distribution). The addition of Y increased EA of Γ structure type. The results of this work contribute to explain the temporal evolution of P structure formation and its regeneration. The use of poultry litter and gypsum in no-till agricultural systems seem to be promising practices for optimizing crop production and minimizing environmental impact.

Ants and termites, as soil engineers, provide many ecosystem services that can be important for the sustainability of agriculture. The aim of this study was to evaluate the impact of land use on ant and termite communities in Colombian savanna landscapes, and to assess whether this impact is associated with the modification of soil physical and chemical properties. Ants and termites were sampled in five different agricultural and semi-natural systems across three regions of the 3 eastern Colombian Llanos: 1) annual crops (maize, soy and rice), 2) rubber plantations, 3) oil palm plantations, 4) improved pastures and 5) semi-natural savannas. A total of 91 ant and 16 termite species were collected. Multivariate analysis revealed that termite communities significantly differed among land uses, but not between regions. Ant communities differed between regions and land uses. Based on between group analyses of termite communities, three groups of land use can be distinguished: one formed by semi-natural savannas and improved pastures, the second by oil palm plantations and annual crops and the third by rubber plantations. General linear models applied separately to each species found 19 significant associations of soil physical or chemical properties, land uses or regions with 15 ant species and 14 significant associations with 6 termite species. Taken together, there is a strong association between land use and ant or termite communities and this influence is likely due to changes in ant and termite habitats resulting from agricultural practices such as tillage, fertilization, and lime addition. These results suggest that annual crops are the most detrimental land use for termites and ants, because their communities are highly sensitive to vegetation cover and agricultural practices such as tillage. Maintaining a high diversity of soil engineers and the ecosystem services they provide likely depends on the maintenance of natural ecosystems in the landscape and the adoption of practices that reduce impacts on soil ecosystem engineers when native ecosystems have been transformed into agricultural systems.

RESUMEN El objetivo de este estudio fue determinar los indicadores que mejor representan la calidad de un suelo del área central de la provincia de Córdoba. El estudio se realizó sobre un Haplustol típico. Se evaluaron seis tratamientos. En cada tratamiento se seleccionaron tres sitios de ensayo, en los que se determinó contenido de carbono orgánico (CO); nitrógeno total (NT); pH; conductividad eléctrica; fósforo extractable (PE); carbono liviano; carbono de ácidos húmicos y carbono de ácidos fúlvicos; densidad aparente; cambio en el diámetro medio ponderado de agregados (CDMP); espesor del horizonte superficial (HzA) y profundidad del CO 3 Ca. Se utilizó análisis de componente principales para evaluar la relación existente entre parámetros de suelo medidos, entre parámetros y tratamientos y entre tratamientos. Los resultados de este estudio muestran que los indicadores más sensibles y sencillos de medir para evaluar calidad de suelos están relacionados a la fertilidad de los mismos: materia orgánica (CO y sus fracciones), NT, PE y a la susceptibilidad a la erosión: CDMP, profundidad del CO 3 Ca y espesor del HzA. La disminución de los contenidos de CO y sus fracciones, macronutrientes (NT y PE) y el aumento en la susceptibilidad a la erosión hídrica a medida que se prolongan los años de agricultura y se incrementan las prácticas tales como monocultivo de soja y siembra convencional, evidencian el deterioro de la calidad del suelo en relación a los sitios bajo bosque nativo que son los que presentan el máximo potencial. Bajo condiciones de semiaridez, la siembra directa no logró mejorar significativamente las características físicas del suelo ni el contenido de CO y sus fracciones cuando se realizó monocultivo de soja. Palabras clave. Propiedades químicas, propiedades físicas, rotaciones, monocultivo, análisis de componentes principales.

This study reports the effect of topography, stubble grazing, tillage and the addition of fertilizer on the organic carbon content and structural stability of a typic Hapludoll topsoil under mixed agricultural production. The organic carbon content was significantly higher in the lower area of the slope when harvest residues were not grazed and when conservation tillage was performed. The interaction tillage x residue showed the highest carbon content to be attained with reduced tillage and no stubble grazing, and the lowest to be attained with conventional tillage with stubble grazing. Comparisons with minimally altered soil showed the loss of organic carbon to oscillate between 80% with conventional tillage when residues were grazed and 77% when conservation tillage systems were used. With respect to quantities of water-stable aggregates available (four diameter ranges), minimal alteration led to the highest percentages of the most coarse aggregates, while with the different treatments the finest and most coarse aggregates showed the highest percentages. The exception was under direct seeding where the distribution was similar to that for minimal soil alteration, though the percentage of the most coarse aggregates was lower. A linear, positive relationship was found between organic carbon and macroaggregate content. These results may help in the choice of technologies that can improve soil quality.

Los autores declaran no tener conflicto de intereses. Artículo científico Análisis comparativo de suelos cultivados y de monte de la provincia del Chaco, Argentina Comparative analysis of cultivated and native forest soils of the province of Chaco, Argentina

Los sistemas productivos agrícolas presentan altos niveles de mecanización con tractores y máquinas cada vez más pesados. Como consecuencia, la compactación de los suelos es un problema emergente, dando como resultado el deterioro de la estructura de muchos suelos y la baja de los rendimientos productivos. El objetivo del presente trabajo fue evaluar el efecto de distintas intensidades de tráfico sobre dos condiciones de suelo: con labranza y bajo siembra directa, sometidos a diferentes intensidades de tráfico. Se compararon dos sistemas de siembra: suelo bajo siembra directa y suelo con labranza. Como subtratamientos se estudió la incidencia del pasaje repetido sobre la misma senda de un tractor de 6,4 Mg resultando en una, cinco y diez pasadas. Para cuantificar la compactación inducida se evaluaron la resistencia a la penetración, la densidad aparente y la profundidad de huella. Además se evaluó la compactación máxima resultante a través del test Proctor (1933). El suelo labrado r...

The widespread degradation of the structure of silty soils under no till systems (NT) that has been observed in recent years is characterized by the presence of a platy structure (P) near the soil surface. Under these conditions, addition of organic and inorganic amendments could have beneficial effects on soil physical properties. We assessed structural regeneration following addition of amendments in an Argiudoll of Paraná, Argentina. Poultry litter (PL) and gypsum (G) were applied, providing an organic and inorganic amendment, respectively. Four treatments were tested: PL (7.5 Mg ha-1), G (3 Mg ha-1), the combination of PL+G (7.5+3 Mg ha-1), and control (T) with no amendment. Description and quantification of the structural state of the soil profile was made using a Visual Soil Evaluation method: "Le profil cultural". Aggregate stability, bulk density, total porosity, pore size distribution and soil shear strength for each soil structure and soil organic carbon (SOC) were determined at two depths. Twenty months after the amendment applications, both PL and PL+G treatments led to a significant increase of SOC in the upper 5 cm of soil. The proportion of Gamma (Γ) structure increased and P declined under PL and PL+G compared with G and T inn the A horizon. Treatments G and PL+G contributed to an increase in average diameter of aggregates in Γ only. The use of PL amendment alone or in combination with G could be a promising strategy to regenerate, in the short-term, the degraded soil structure under NT.

En estudio evaluó las características del suelo que influyen en el crecimiento de la especie Eucaliptus urograndis en plantaciones forestales comerciales mediante la caracterización de suelos en campo y laboratorio en 18 parcelas de muestreo, distribuidos en tres estratos de crecimientos. Los resultados de la caracterización de los perfiles de suelo en los 3 estratos de crecimiento indican que la especie se ve favorecido en suelos desarrollados profundos, con horizontes genéticos definidos como “A” muy superficial, horizonte “B” iluvial bien desarrollado y C en proceso de formación, profundidad efectiva superior a los 40 cm, buen drenaje, estructura granular y en bloques, con texturas que van de franco, franco arenoso y arena franca. El crecimiento se ve limitado en suelos superficiales y con mal drenaje. Según los análisis estadísticos de correlación y regresión, el contenido de la fracción arena en el suelo está relacionado con el crecimiento, mostrando así una correlación positiv...

Ants and termites, as soil engineers, provide many ecosystem services that can be important for the sustainability of agriculture. The aim of this study was to evaluate the impact of land use on ant and termite communities in Colombian savanna landscapes, and to assess whether this impact is associated with the modification of soil physical and chemical properties. Ants and termites were sampled in five different agricultural and semi-natural systems across three regions of the 3 eastern Colombian Llanos: 1) annual crops (maize, soy and rice), 2) rubber plantations, 3) oil palm plantations, 4) improved pastures and 5) semi-natural savannas. A total of 91 ant and 16 termite species were collected. Multivariate analysis revealed that termite communities significantly differed among land uses, but not between regions. Ant communities differed between regions and land uses. Based on between group analyses of termite communities, three groups of land use can be distinguished: one formed by semi-natural savannas and improved pastures, the second by oil palm plantations and annual crops and the third by rubber plantations. General linear models applied separately to each species found 19 significant associations of soil physical or chemical properties, land uses or regions with 15 ant species and 14 significant associations with 6 termite species. Taken together, there is a strong association between land use and ant or termite communities and this influence is likely due to changes in ant and termite habitats resulting from agricultural practices such as tillage, fertilization, and lime addition. These results suggest that annual crops are the most detrimental land use for termites and ants, because their communities are highly sensitive to vegetation cover and agricultural practices such as tillage. Maintaining a high diversity of soil engineers and the ecosystem services they provide likely depends on the maintenance of natural ecosystems in the landscape and the adoption of practices that reduce impacts on soil ecosystem engineers when native ecosystems have been transformed into agricultural systems.

Background and Aims Plants and earthworms are key ecosystem engineers and important regulators of soil aggregation and C dynamics, yet research to date has mainly considered their impacts in isolation thereby ignoring potential interactions between these organisms. Methods We conducted a microcosm experiment under greenhouse conditions to assess the impacts of plants (Brachiaria decumbens) and earthworms (Pontoscolex corethrurus) on soil structure and C stabilization. Aggregate stability was assessed by wet-sieving. Large macroaggregates (>2 mm) were also visually separated according to origin (e.g., earthworms, roots) and then further fractionated into particle size fractions to assess aggregate composition and C distribution. Results Earthworms increased aboveground biomass of B. decumbens by nearly 30 %. The presence of plant roots increased aggregate stability (mean weight diameter) by 2.6 %. While earthworms alone had no simple impacts on aggregation, a significant interaction revealed that earthworms increased aggregate stability in the presence of roots by 6 % when compared to microcosms without plants. Additionally, the presence of roots increased the C concentration of coarse particulate organic matter in earthworm casts, while earthworms increased C storage in microaggregates and the silt and clay fraction within root-derived aggregates. Conclusions These findings suggest that plants and earthworms are intimately linked in soil aggregate formation and that both organisms need be considered simultaneously for proper management of soils. Keywords Brachiaria decumbens. Ecosystem engineers. Pontoscolex corethrurus. Soil aggregation. Tropical pastures Abbreviations SOM soil organic matter CAST earthworm casts RHIZ soil aggregates associated with rhizosphere PHYS aggregates formed by physiochemical and/or microbial processes NON non-macroaggregated soil cPOM coarse particulate organic matter

The widespread degradation of the structure of silty soils under no till systems (NT) that has been observed in recent years is characterized by the presence of a platy structure (P) near the soil surface. Under these conditions, addition of organic and inorganic amendments could have beneficial effects on soil physical properties. We assessed structural regeneration following addition of amendments in an Argiudoll of Paraná, Argentina. Poultry litter (PL) and gypsum (G) were applied, providing an organic and inorganic amendment, respectively. Four treatments were tested: PL (7.5 Mg ha-1), G (3 Mg ha-1), the combination of PL+G (7.5+3 Mg ha-1), and control (T) with no amendment. Description and quantification of the structural state of the soil profile was made using a Visual Soil Evaluation method: "Le profil cultural". Aggregate stability, bulk density, total porosity, pore size distribution and soil shear strength for each soil structure and soil organic carbon (SOC) were determined at two depths. Twenty months after the amendment applications, both PL and PL+G treatments led to a significant increase of SOC in the upper 5 cm of soil. The proportion of Gamma (Γ) structure increased and P declined under PL and PL+G compared with G and T inn the A horizon. Treatments G and PL+G contributed to an increase in average diameter of aggregates in Γ only. The use of PL amendment alone or in combination with G could be a promising strategy to regenerate, in the short-term, the degraded soil structure under NT.

In the Pampas region of Argentina agriculture is dominated by intensive no-till (NT) soybean cropping which produce negative consequences on soil quality. A group of farmers started to use the Good Agricultural Practices (GAP) which include a higher crop rotation, use of winter cover crops and nutrient restoration. In this NT system earthworms have a significant role in soil functioning, particularly in organic matter cycling and soil structure formation. The aim of this paper was to examine the contribution of earthworm activity to the process of C incorporation and soil structure maintenance in soils with different NT variants of: NT with GAP for 30 years (NT + r30); NT with some of the GAP for 12 years (NT-r12) and NT with soybean monoculture (NTm). Also a natural grassland (NA) was sampled as a reference. Earthworm aggregates were obtained by gently separating them from surrounding soil. Fine (HOC) and coarse (POC) organic matter fractions, water-stable aggregates (WSA) and mean weight diameter (MWD) were calculated for earthworm aggregates and bulk soil. In all sites only one species (Aporrectodea caliginosa) was found, with higher density in the NA, followed by NT + r30, that had about 9 times more earthworms than NTm. The number of earthworm aggregates was higher in the NT + r30 followed by the NA, both showing differences with the other NT systems. The earthworm aggregates in NA and NT + r30 had significantly more POC than the surrounding soil (230% increase in NA and 100% NT + r30). Earthworm casts had higher values of MWD and WSA than physical soil aggregates in both NA and NT + r30 management treatments. Our results show the existence of a positive feedback loop we called earthworm-driven virtuous cycle. The increase in earthworm abundance promotes higher production of earthworm aggregates which are richer in organic matter and more water stable than the surrounding soil. This has favourable results in terms of soil quality but also increase crop yields (57% in maize and 18% in soybean), by means of biologically mediated soil processes, which is a highly desirable way to sustainability of agricultural production. Farmers, politicians and the whole society should pay more attention to soil as a key component supporting agricultural production by means of internal biological soil functioning.

  Among the problems of physical degradation, compaction and densification are the main ones, and they cause strong decreases in subsequent crop yields thereof. The degradation of soil structure is a worldwide problem that can occur in all soils and livestock production levels. Given the above, this paper aims to analyze the main changes in the internal structure of the soil as a result of compaction by trampling of animals. Soil compaction due to the collapse or decrease in pore spaces, is the most common cause of physical restraint to growth and root development. As an aggravating factor, degradation of soil structure is regarded as the type of land degradation more difficult to locate and retrain; the reason is that this degradation is a subsurface phenomenon. Finally it is to establish some possible solutions to this problem, including the main method of restoring the porosity of the boundary layers of root growth is to apply biological methods as used, for example, the roots of...

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Para evaluar el tiempo de uso del suelo dedicados al monocultivo de caña panelera Saccharum officinarum y su efecto en algunas de sus propiedades físicas, se tomaron muestras de suelo sin disturbar en anillos de acero de 5 cm de diámetro y 11 cm de largo, a dos profundidades en el perfil del suelo. Posteriormente, se determinó la densidad aparente, la porosidad total y la distribución de poros. En general, los valores obtenidos de densidad aparente tienden a disminuir con el transcurrir de los años, así mismo la porosidad y distribución total, se ven afectadas por el uso de monocultivo en largos periodos de tiempo. Palabras claves: cultivo intensivo, estructura del suelo.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Response to G.W. Sileshi's Letter to the Editor on AGEE13857 (2015): Exclusion of soil macrofauna did not affect soil quality-statistical artefact or true lack of effect? The International Center for Tropical Agriculture (CIAT) believes that open access contributes to its mission of reducing hunger and poverty, and improving human nutrition in the tropics through research aimed at increasing the eco-efficiency of agriculture. CIAT is committed to creating and sharing knowledge and information openly and globally. We do this through collaborative research as well as through the open sharing of our data, tools, and publications.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The environmental impact of pastured pork production systems is related to climate, soil type, vegetative ground cover species and grazing pressure. Each situation requires a specific analysis. Different strategies have proven to be beneficial to reduce the environmental impact of pastured pork, including: implementing rotational management, employing an appropriate stocking rate, periodically moving shelters, feeding and drinking structures, and utilizing crops for soil bioremediation. In order to maintain a vegetative ground cover of 75%, it is advisable to implement rotational grazing systems with stocking rates lower than 50 growing-finishing pigs/ha or 10 gestating sows/ha.

En Uruguay, coexisten los sistemas de produccion de cerdos en confinamiento y los sistemas extensivos con acceso a pasturas. Entre ambos existen diferencias notables en cuanto a costes de produccion, bienestar animal e implicaciones medioambientales. Por otro lado, los episodios de sequia provocados por el fenomeno �la Nina� pueden alterar el comportamiento normal de los sistemas pastoriles. En este trabajo se analiza la dinamica de los nutrientes y su posible efecto ambiental en dos ciclos de cebo de cerdos alojados en un sistema de produccion al aire libre, denominado �a campo�. Los animales contaron con una parcela de encierro permanente donde se localizaba el refugio, comederos y bebederos. Tuvieron acceso a varias parcelas de pastoreo consecutivamente, estando cada parcela accesible durante una semana. La mayor concentracion de los nutrientes provenientes de las deyecciones de los animales, se acumulan en el area circundante al refugio y los comederos, siendo menor la concentra...

La materia orgánica del suelo incide en los ciclos de nutrientes y propiedades del suelo y tiene claras implicaciones para el uso sostenible del mismo. El objetivo del trabajo fue estudiar cambios en el COS en un Brunosol (Canelones Uruguay), luego de 12 años con cerdos a campo en comparación con el suelo testigo (sin cerdos). Las muestras de suelo fueron colectadas en superficie (0-15 cm) en un área testigo y 6 parcelas (20x75 m c/u), en 3 zonas diferenciadas de manejo por parcela (n= 24). Se determinó COS, C y P en la materia orgánica particulada de 50-200 μm (MOP50) y 200-2000 μm (MOP200), C en la materia orgánica no particulada <50 μm (MONP), P disponible (Bray) y K extractable. Si bien el sistema globalmente disminuyó la materia orgánica del suelo, en la parcela que mantuvo menor carga animal se incrementó. Sumado a la heterogeneidad en la distribución del COS observada, refuerza la conclusión de que hay potencial para buscar manejos que posibiliten conservar y/o mejorar el suelo con cerdos a campo.

La materia orgánica del suelo incide en los ciclos de nutrientes y  propiedades del suelo y tiene claras implicaciones para el uso sostenible del mismo. Los ecosistemas de praderas han sido históricamente sobrepastoreados, resultando en pérdidas de carbono orgánico del suelo (COS). La producción de cerdos al aire libre puede tener ventajas de bienestar animal, económicas, sociales y de calidad de carne en relación al confinamiento, pero requiere medidas conservacionistas del suelo con el fin de evitar problemas ambientales.
El objetivo del trabajo fue estudiar los cambios en el carbono orgánico del suelo en un Brunosol (Canelones Uruguay), luego de 12 años con cerdos a campo en comparación con el suelo testigo (sin cerdos).

La producción de cerdos a campo es una alternativa para productores familiares, pero investigaciones recientes han demostrado que pueden alterar  negativamente propiedades químicas del suelo. Es necesario contar con información local sobre tipo y distribución de impactos sobre el mismo,  para estudiar causas de degradación y alternativas de manejo. El objetivo fue estudiar la variabilidad espacial en superficie (0-15 cm) de  características químicas en un Brunosol (Canelones, Uruguay), por un sistema de cerdos a campo y compararlas con un suelo testigo (sin cerdos).
Se muestreó en grilla (5x5 m) en 4 parcelas, para mapear la variabilidad espacial. En base a éste se realizó un segundo muestreo en un área  testigo y 6 parcelas (1500 m2 c/u), con 3 zonas diferenciadas de manejo (servicio, pastoreo e intermedia) por parcela (n=24). Se determinó  carbono orgánico (COS), Nnitrato, N-amonio, fósforo (Bray) y P en solución, pH y conductividad eléctrica (CE). En la zona de servicio aumentó  estadísticamente en relación al testigo la concentración de nitrato, P disponible y en solución y la CE, en tanto disminuyó NH y COS. 4 En la zona de pastoreo aumentó el P disponible, en tanto disminuyó el NH , COS y pH. La variabilidad espacial del N, fósforo y 4 CE fue influenciada por la distancia a las instalaciones. El sistema generó heterogeneidad espacial, incrementando riesgos ecológicos asociados a pérdidas de N, P y disminución de COS.

Summary

Outdoor swine production is an alternative for family farmers, but recent research has shown that they can negatively alter soil chemical properties. It is necessary to have local information on the type and distribution of impacts, to study causes of degradation and management alternatives. The aim was to study the spatial variability in surface (0-15 cm) of chemical characteristics in a Brunosol (Canelones Uruguay), by a system of outdoor swine and compared with a control soil (without pigs). Sampling was made in a grid (5x5 m) in 4 plots, to map the spatial variability. Based on this the second sampling was performed in a control area and 6 plots (1500 m2 each), with 3 different management areas (service, grazing and intermediate) per plot (n = 24). We measured organic carbon (SOC), NO3-N, NH4-N, P (Bray) and in solution, pH and electrical conductivity (EC). In the service area increased statistically in relation to the control the concentration of nitrate-N, available P, P in solution and the EC, decreasing NH4 and SOC. In the grazing area available P increased, while NH4, COS and pH decreased. Spatial variability of N, phosphorus and CE was influenced by the distance to the service. The system generated spatial heterogeneity, increasing ecological risks associated with N and P losses and decrease in COS.

Key words: grazing sows - nutrient distribution - soil organic carbon

La producción de cerdos a campo puede ser una alternativa a los problemas de bienestar animal, contaminación y bioseguridad de los sistemas confinados. Pero algunas prácticas de manejo pueden modificar la variabilidad espacial de atributos químicos del suelo y producir en ocasiones problemas ambientales. El objetivo de este trabajo fue estudiar la variabilidad espacial de características químicas en un Brunosol (Canelones Uruguay), luego de 12 años de instalado un criadero de cerdos a campo y compararlas con un suelo testigo (sin cerdos). Las muestras de suelo fueron colectadas en superficie (0-15 cm) en una zona testigo y 6 parcelas (1500 m2 c/u), con 3 zonas diferenciadas de manejo por parcela (n= 24). Las áreas seleccionadas fueron: de servicio (bebedero, comederos y refugios), área de pastoreo más lejana y la intermedia. Complementariamente se realizó un muestreo en grilla (5x5 m) en 4 de esas parcelas. Los atributos químicos de los suelos estudiados fueron: carbono orgánico (COS), N-nitrato, N-amonio, fósforo (Bray) y P en solución, pH y conductividad eléctrica (CE). La comparación de las variables entre el suelo sin y con cerdos, así como la diferencia entre zonas dentro de éste último se realizó estadísticamente mediante ANOVA y test no paramétrico Kruskal-Wallis, y por medio de herramientas geoestadísticas se construyeron mapas utilizando interpolación Splines. En la zona de servicio aumentó estadísticamente en relación al testigo la concentración de nitrato, P disponible y en solución y la CE en tanto disminuyo NH4 y COS. En la zona de pastoreo solo aumento en relación al testigo el P disponible, disminuyendo el NH4, COS y el pH. En el suelo con cerdos la variabilidad espacial del N, fósforo y CE fue influenciada por la distancia a las instalaciones (bebedero, comedero y refugios), siendo no significativa la influencia sobre el COS y el pH. El sistema generó heterogeneidad espacial, incrementando riesgos ecológicos asociados a pérdidas de N, P y la disminución de COS, lo cual sugiere que el manejo debe ser modificado con el fin de mejorar el potencial biofísico de sustentabilidad.

En años recientes se ha incrementado el interes y la producción ecológica de cerdos en sistemas al aire libre, considerados por varios autores como una alternativa a los grandes sistemas confinados, por ser respetuosos del comportamiento animal y ambientalmente amigables.  Con el objetivo de estudiar impactos sobre el suelo de un sistema de cerdos en pastoreo luego de 12 años, se muestreó 6 parcelas de 1500 m2 y un área testigo (sin cerdos). El suelo es un Brunosol y las cerdas se manejan en con cargas promedio de 6 cerdas ha-1 año-1, con dieta a base de ración y acceso permanente a pasturas. El sistema produjo modificaciones en propiedades físicas, químicas y biológicas del suelo, generando heterogeneidad espacial en zonas diferenciadas de manejo. La zona de servicio concentró los mayores impactos y la de pastoreo (75% del área) los menores. El sistema ocasionó compactación del suelo, superando los 2 MPa de RP solo en áreas reducidas de la zona de servicio, que fue la más compactada. La MO se redujo de 4,7% en el suelo testigo a 3,9% en el suelo con cerdos en la capa superficial, disminuyendo también 17% en profundidad, explicado fundamentalmente por la disminución de la MONP y sin diferencias significativas entre las zonas de las parcelas. Se incrementó el contenido de P, NO3 y K fundamentalmente en el área de servicio, correlacionados con la conductividad eléctrica del suelo, la cual no llegó a valores problemáticos. El exceso de N fue escasamente acumulado en el suelo, incrementando el riesgo de contaminación de aguas. En la zona de pastoreo el pH disminuyó 0,4 unidades en relación al testigo (p<0,05), la cual no se diferenció significativamente con el área de servicio. Algunos impactos se extendieron en forma significativa (p<0,05) a la capa de 15-30 cm (RP, COS, P, NH4 y CE). No se observó problemas de acumulación de metales pesados (Zn y Cu). Producir cerdos a campo puede ser una alternativa de monores costos de producción a sistemas confinados, pero los resultados sugieren que es una actividad con potencial de generar problemas ambientales por inadecuadas prácticas de manejo.