Impactos de los 'pools de siembra' en la estructura social agraria : Una aproximación a las transformaciones en los espacios centrales de la provincia de Santa Fe (Argentina)

En los últimos años se han producido importantes transformaciones en la activiad agrícola argentina. Una de ellas es la aparición de nuevos formas de organización de la agricultura que se denominan genéricamente 'pools de siembra', los cuales impactan en los territorios locales modificando tanto los roles y las funciones de los actores agrarios tradicionales como las relaciones que mantienen entre ellos. Bajo la hipótesis de que estas nuevas formas de organización de la agricultura, llevadas a cabo por actores de tipo más financiero que socioproductivo, aceleran los procesos de concentración y desterritorialización de la riqueza, se avanza en este trabajo sobre cuatro aspectos. En primer lugar, se caracteriza a los actores actuales vinculados a la producción primaria, considerando su trayectoria y su relación con la actividad agrícola y con el espacio local. En segundo lugar, nos concentramos en esas nuevas formas de organización de la agricultura, tratando de mostrar que detrás de la denominación de 'pools de siembra' se esconde una diversidad de actores; para ello, el presente estudio articula tres variables principales: la duración del emprendimiento agrícola, la forma jurídica adoptada y el actor responsable de la gestión. En tercer lugar, se profundiza en las lógicas decisorias de los propietarios rentistas, actores clave junto con los contratistas en el avance de los pools de siembra. Por último, se describe algunos de los impactos actualmente perceptibles de estas nuevas formas de organización en los espacios centrales santafesinos

Impactos de los 'pools de siembra' en la estructura social agraria : Una aproximación a las transformaciones en los espacios centrales de la provincia de Santa Fe (Argentina)

En los últimos años se han producido importantes transformaciones en la activiad agrícola argentina. Una de ellas es la aparición de nuevos formas de organización de la agricultura que se denominan genéricamente 'pools de siembra', los cuales impactan en los territorios locales modificando tanto los roles y las funciones de los actores agrarios tradicionales como las relaciones que mantienen entre ellos. Bajo la hipótesis de que estas nuevas formas de organización de la agricultura, llevadas a cabo por actores de tipo más financiero que socioproductivo, aceleran los procesos de concentración y desterritorialización de la riqueza, se avanza en este trabajo sobre cuatro aspectos. En primer lugar, se caracteriza a los actores actuales vinculados a la producción primaria, considerando su trayectoria y su relación con la actividad agrícola y con el espacio local. En segundo lugar, nos concentramos en esas nuevas formas de organización de la agricultura, tratando de mostrar que detrás de la denominación de 'pools de siembra' se esconde una diversidad de actores; para ello, el presente estudio articula tres variables principales: la duración del emprendimiento agrícola, la forma jurídica adoptada y el actor responsable de la gestión. En tercer lugar, se profundiza en las lógicas decisorias de los propietarios rentistas, actores clave junto con los contratistas en el avance de los pools de siembra. Por último, se describe algunos de los impactos actualmente perceptibles de estas nuevas formas de organización en los espacios centrales santafesinos

Impactos de los 'pools de siembra' en la estructura social agraria : Una aproximación a las transformaciones en los espacios centrales de la provincia de Santa Fe (Argentina)

En los últimos años se han producido importantes transformaciones en la activiad agrícola argentina. Una de ellas es la aparición de nuevos formas de organización de la agricultura que se denominan genéricamente 'pools de siembra', los cuales impactan en los territorios locales modificando tanto los roles y las funciones de los actores agrarios tradicionales como las relaciones que mantienen entre ellos. Bajo la hipótesis de que estas nuevas formas de organización de la agricultura, llevadas a cabo por actores de tipo más financiero que socioproductivo, aceleran los procesos de concentración y desterritorialización de la riqueza, se avanza en este trabajo sobre cuatro aspectos. En primer lugar, se caracteriza a los actores actuales vinculados a la producción primaria, considerando su trayectoria y su relación con la actividad agrícola y con el espacio local. En segundo lugar, nos concentramos en esas nuevas formas de organización de la agricultura, tratando de mostrar que detrás de la denominación de 'pools de siembra' se esconde una diversidad de actores; para ello, el presente estudio articula tres variables principales: la duración del emprendimiento agrícola, la forma jurídica adoptada y el actor responsable de la gestión. En tercer lugar, se profundiza en las lógicas decisorias de los propietarios rentistas, actores clave junto con los contratistas en el avance de los pools de siembra. Por último, se describe algunos de los impactos actualmente perceptibles de estas nuevas formas de organización en los espacios centrales santafesinos

Soil carbon saturation: Linking concept and measurable carbon pools

The soil C saturation concept suggests a limit to whole soil organic carbon (SOC) accumulation determined by inherent physicochemical characteristics of four soil C pools: unprotected, physically protected, chemically protected, and biochemically protected. Previous attempts to quantify soil C sequestration capacity have focused primarily on silt and clay protection and largely ignored the effects of soil structural protection and biochemical protection. We assessed two contrasting models of SOC accumulation, one with no saturation limit (i.e., linear first-order model) and one with an explicit soil C saturation limit (i.e., C saturation model). We isolated soil fractions corresponding to the C pools (i.e., free particulate organic matter POM], microaggregate-associated C, silt- and clay-associated C, and non-hydrolyzable C) from eight long-term agroecosystern experiments across the United States and Canada. Due to the composite nature of the physically protected C pool, we firactioned it into mineral- vs. POM-associated C. Within each site, the number of fractions fitting the C saturation model was directly related to maximum SOC content, suggesting that a broad range in SOC content is necessary to evaluate fraction C saturation. The two sites with the greatest SOC range showed C saturation behavior in the chemically, biochemically, and some mineral-associated fractions of the physically protected pool. The unprotected pool and the aggregate-protected POM showed linear, nonsaturating behavior. Evidence of C saturation of chemically and biochemically protected SOC pools was observed at sites far from their theoretical C saturation level, while saturation of aggregate-protected fractions occurred in soils closer to their C saturation level.

Does the acid hydrolysis-incubation method measure meaningful soil organic carbon pools?

The literature was reviewed and analyzed to determine the feasibility of using a combination of acid hydrolysis and CO2-C release during long-term incubation to determine soil organic carbon (SOC) pool sizes and mean residence times (MRTs). Analysis of 1100 data points showed the SOC remaining after hydrolysis with 6 M HCI ranged from 30 to 80% of the total SOC depending on soil type, depth, texture, and management. Nonhydrolyzable carbon (NHC) in conventional till soils represented 48% of SOC; no-till averaged 56%, forest 55%, and grassland 56%. Carbon dates showed an average of 1200 yr greater MRT for the NHC fraction than total SOC. Longterm incubation, involving measurement of CO2 evolution and curve fitting, measured active and slow pools. Active-pool C comprised 2 to 8% of the SOC with MRTs of days to months; the slow pool comprised 45 to 65% of the SOC and had MRTs of 10 to 80 yr. Comparison of field C-14 and (13) C data with hydrolysis-incubation data showed a high correlation between independent techniques across soil types and experiments. There were large differences in MRTs depending on the length of the experiment. Insertion of hydrolysis-incubation derived estimates of active (C-a), slow (C-s), and resistant Pools (C-r) into the DAYCENT model provided estimates of daily field CO2 evolution rates. These were well correlated with field CO2 measurements. Although not without some interpretation problems, acid hydrolysis-laboratory incubation is useful for determining SOC pools and fluxes especially when used in combination with associated measurements.

Nitrogen pools and fluxes in grassland soils sequestering carbon

Carbon sequestration in agricultural, forest, and grassland soils has been promoted as a means by which substantial amounts of CO2 may be removed from the atmosphere, but few studies have evaluated the associated impacts on changes in soil N or net global warming potential (GWP). The purpose of this research was to ( 1) review the literature to examine how changes in grassland management that affect soil C also impact soil N, ( 2) assess the impact of different types of grassland management on changes in soil N and rates of change, and (3) evaluate changes in N2O fluxes from differently managed grassland ecosystems to assess net impacts on GWP. Soil C and N stocks either both increased or both decreased for most studies. Soil C and N sequestration were tightly linked, resulting in little change in C: N ratios with changes in management. Within grazing treatments N2O made a minor contribution to GWP (0.1-4%), but increases in N2O fluxes offset significant portions of C sequestration gains due to fertilization (10-125%) and conversion (average = 27%). Results from this work demonstrate that even when improved management practices result in considerable rates of C and N sequestration, changes in N2O fluxes can offset a substantial portion of gains by C sequestration. Even for cases in which C sequestration rates are not entirely offset by increases in N2O fluxes, small increases in N2O fluxes can substantially reduce C sequestration benefits. Conversely, reduction of N2O fluxes in grassland soils brought about by changes in management represents an opportunity to reduce the contribution of grasslands to net greenhouse gas forcing.

Carbon pools and fluxes along an environmental gradient in northern Arizona

Carbon pools and fluxes were quantified along an environmental gradient in northern Arizona. Data are presented on vegetation, litter, and soil C pools and soil CO2 fluxes from ecosystems ranging from shrub-steppe through woodlands to coniferous forest and the ecotones in between. Carbon pool sizes and fluxes in these semiarid ecosystems vary with temperature and precipitation and are strongly influenced by canopy cover. Ecosystem respiration is approximately 50 percent greater in the more mesic, forest environment than in the dry shrub-steppe environment. Soil respiration rates within a site vary seasonally with temperature but appear to be constrained by low soil moisture during dry summer months, when approximately 75% of total annual soil respiration occurs. Total annual amount of CO2 respired across all sites is positively correlated with annual precipitation and negatively correlated with temperature. Results suggest that changes in the amount and periodicity of precipitation will have a greater effect on C pools and fluxes than will changes in temperature :in the semiarid Southwestern United States.

Implications of patterns of carbon pools and fluxes across a semiarid environmental gradient

Landscape scale environmental gradients present variable spatial patterns and ecological processes caused by climate, topography and soil characteristics and, as such, offer candidate sites to study environmental change. Data are presented on the spatial pattern of dominant species, biomass, and carbon pools and the temporal pattern of fluxes across a transitional zone shifting from Great Basin Desert scrub, up through pinyon-juniper woodlands and into ponderosa pine forest and the ecotones between each vegetation type. The mean annual temperature (MAT) difference across the gradient is approximately 3 degrees C from bottom to top (MAT 8.5-5.5) and annual precipitation averages from 320 to 530 mm/yr, respectively. The stems of the dominant woody vegetation approach a random spatial pattern across the entire gradient, while the canopy cover shows a clustered pattern. The size of the clusters increases with elevation according to available soil moisture which in turn affects available nutrient resources. The total density of woody species declines with increasing soil moisture along the gl-adient, but total biomass increases. Belowground carbon and nutrient pools change from a heterogenous to a homogenous distribution on either side of the woodlands. Although temperature controls the: seasonal patterns of carbon efflux from the soils, soil moisture appears to be the primary driving variable, but response differs underneath the different dominant species, Similarly, decomposition of dominant litter occurs faster-at the cooler and more moist sites, but differs within sites due to litter quality of the different species. The spatial pattern of these communities provides information on the direction of future changes, The ecological processes that we documented are not statistically different in the ecotones as compared to the: adjoining communities, but are different at sites above the woodland than those below the woodland. We speculate that an increase in MAT will have a major impact on C pools and C sequestering and release processes in these semiarid landscapes. However, the impact will be primarily related to moisture availability rather than direct effects of an increase in temperature. (C) 1998 Elsevier Science B.V.

Rock pools of critical thought : finding a place to think through my higher degree and what a PhD was all about

The rock pools, salt pans, cliffs and bluffs, and the banks of the Coorooman and Pumpkin Creeks within Darumbal and Woppaburra Country are used as a backdrop in this paper, which offers an exploration of one woman’s quest to undertake her PhD and develop as an Indigenous scholar. The paper describes this Country and the use of Country to nourish, develop, stimulate and support the intellect. It draws on Australian and international literature to demonstrate the intellectual growth and development of Indigenous scholars. The paper offers a highly personal narrative of intellectual journeying which shows how we can be agents of change and power in our individual lives, even while power is being exercised over us and we are being oppressed and marginalised as Indigenous peoples.

New sale and leasing requirements for owners of swimming pools and their application to strata schemes

This article considers the changes to the Swimming Pools Act 1992 (NSW)(Act) which established a State-wide online register of all private swimming pools in NSW requiring pool owners to register their pools by 19 November 2013. Amendments to the Act introduced changes to the conveyancing and residential tenancy regulations to require vendors and landlords to have a valid Compliance Certificate issued for their swimming pool before offering the property for sale or lease. This article provides a brief overview of the new sale and leasing requirements effective from 29 April 2014, focusing on its application to lot owners within strata and community title schemes and other owners of water front properties with pools on Crown Land Reserves.

Long-term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. IX. Simulation of soil carbon and nitrogen pools using CENTURY model

Cultivation and cropping of soils results in a decline in soil organic carbon and soil nitrogen, and can lead to reduced crop yields. The CENTURY model was used to simulate the effects of continuous cultivation and cereal cropping on total soil organic matter (C and N), carbon pools, nitrogen mineralisation, and crop yield from 6 locations in southern Queensland. The model was calibrated for each replicate from the original datasets, allowing comparisons for each replicate rather than site averages. The CENTURY model was able to satisfactorily predict the impact of long-term cultivation and cereal cropping on total organic carbon, but was less successful in simulating the different fractions and nitrogen mineralisation. The model firstly over-predicted the initial (pre-cropping) soil carbon and nitrogen concentration of the sites. To account for the unique shrinking and swelling characteristics of the Vertosol soils, the default annual decomposition rates of the slow and passive carbon pools were doubled, and then the model accurately predicted initial conditions. The ability of the model to predict carbon pool fractions varied, demonstrating the difficulty inherent in predicting the size of these conceptual pools. The strength of the model lies in the ability to closely predict the starting soil organic matter conditions, and the ability to predict the impact of clearing, cultivation, fertiliser application, and continuous cropping on total soil carbon and nitrogen.