MAGGnet: an international network to foster mitigation of agricultural greenhouse gases.

Research networks provide a framework for review, synthesis and systematic testing of theories by multiple scientists across international borders critical for addressing global-scale issues. In 2012, a GHG research network referred to as MAGGnet (Managing Agricultural Greenhouse Gases Network) was established within the Croplands Research Group of the Global Research Alliance on Agricultural Greenhouse Gases (GRA). With involvement from 46 alliance member countries, MAGGnet seeks to provide a platform for the inventory and analysis of agricultural GHG mitigation research throughout the world. To date, metadata from 315 experimental studies in 20 countries have been compiled using a standardized spreadsheet. Most studies were completed (74%) and conducted within a 1-3-year duration (68%). Soil carbon and nitrous oxide emissions were measured in over 80% of the studies. Among plant variables, grain yield was assessed across studies most frequently (56%), followed by stover (35%) and root (9%) biomass. MAGGnet has contributed to modeling efforts and has spurred other research groups in the GRA to collect experimental site metadata using an adapted spreadsheet. With continued growth and investment, MAGGnet will leverage limited-resource investments by any one country to produce an inclusive, globally shared meta-database focused on the science of GHG mitigation

Nitrogen fertilization in maize under irrigated and rainfed conditions: abstract.

Crop production in Uruguay has changed significantly in recent years, not only in terms of expansion of cultivated area but inits main features. These changes came along with significant increase in land prices and agricultural inputs causing intensificationon land use. In order to get high profits the traditional crop-pasture rotations should be strongly oriented to a continuous croppingsystem and strengthened on grain crops. The potential of agricultural systems is highly dependent on rainfall, therefore, theadoption of irrigation represents an attractive alternative to increase productivity and reduce vulnerability of productive systems.Maize performance and its C4 metabolism enhancing water use efficiency represent an excellent choice for farmers. Nitrogen(N) is one of the main nutrients affecting plant growth and maize grain yield response to N application is well known. In order toreduce N losses, increase uptakes and improve N use efficiency, optimum amount of water and N should be applied. Theobjective of this study was to assess the interaction between irrigation and N application rates and its effect upon yield. A threeyear field experiment was carried out in Colonia, Uruguay (34º25´S, 58º0´W), at the Experimental Station of the NationalAgricultural Research Institute (INIA) "La Estanzuela", in three growing seasons (2011-2014), under a Vertic Argiudoll soil. Theexperimental treatments consisted in eight urea treatments with four levels of N application (0, 50, 100, 150 and 200 KgN/ha)at three different phenological moments (V6, V10 and V14) under rainfed and supplementary irrigated conditions. The studyshowed that the average grain yield on irrigated conditions was 12.060 ± 2282 kg/ha for all treatments and 7.089 ± 1615 kg/ha under rainfed conditions. Results indicated that due to the strategies of N application and irrigation water application, yieldsincreased as N rate application increased. Furthermore, results showed that under rainfed conditions N treatments did nottranslated in significantly increased grain yields, indicating that when water is scarce, the effect of nutrients are scattered, and theachievable grain yields are not reached. The maximum grain yield was obtained for 200 kgN/ha application treatments,showing an increase of 5.337 kg/ha under irrigated conditions, while on rainfed conditions was only 1.500 kg/ha. However, inorder to avoid N losses and improve N use efficiency, the amount of N fertilizer should not be applied at one time. It can beconcluded that supplementary irrigation is a fundamental technology not only to maximize and stabilize grain yields but toenhance N use efficiency

Respuesta del cultivo de soja al azufre en argiudoles típicos del sudoeste de Uruguay. [Soybean response to sulfur in typic arguidolls of southwestern Uruguay.].

RESUMEN.El azufre (S) es un nutriente esencial para el crecimiento y desarrollo de las plantas. La intensificación agrícola que ocurrió en Uruguay en particular en la última década, ha incrementado el riesgo de ocurrencia de deficiencias nutricionales. El objetivo fue estudiar la respuesta al agregado de S en soja y evaluar la concentración de sulfato en el suelo y el potencial de mineralización de nitrógeno (PMN) como indicadores de disponibilidad de S. Se realizaron experimentos parcelarios en 13 sitios durante seis estaciones de crecimiento en la Estación Experimental La Estanzuela (Colonia, Uruguay) en Argiudoles típicos de la zona. El S fue aplicado en forma de yeso (sulfato de calcio) a dosis de 0, 15, 30 y 45 kg de S ha-1, en tratamientos dispuestos en bloques al azar con cuatro repeticiones. Las variaciones en cantidad y distribución de las lluvias afectaron el rendimiento en grano y la respuesta a la fertilización. Solamente en dos sitios se observó un incremento significativo en grano, el cual fue cercano a 15%. Para los suelos estudiados, la probabilidad de encontrar respuesta positiva al S resultó alta cuando la concentración de sulfatos fue menor a 5 mg kg-1 al momento de la siembra. En ese caso los incrementos oscilaron entre 204 y 467 kg ha-1. Cuando el nivel de sulfatos es mayor a dicho valor, sería poco probable obtener incrementos por el agregado de yeso, con la posibilidad de observar incluso respuestas negativas. No se encontró relación entre el PMN y la respuesta en rendimiento.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.SUMMARY.Sulfur (S) is an essential nutrient, necessary to maintain crop productivity. Agriculture intensification in Uruguay has increased the risk of nutrient deficiencies in soils. The goal of this study was to explore soybean response to S application and the feasibility of using soil sulfate concentration, and potentially mineralizable nitrogen (PMN) as indicators of S-availability. Thirteen field trials were conducted during six growing seasons (2007 to 2012) at the Experimental Station La Estanzuela, Colonia, on typical Argiudols of the area. Sulfur as gypsum was applied at rates of 0, 15, 30 and 45 kg S ha-1, with treatments allocated in four complete randomized blocks. Variation in precipitation amount and distribution affected soybean grain yield across the years and thereby fertilization response. Only in two trials yield responses were statistically significant, with increases that amounted about 15 %. For the soils studied, positive responses to S would be likely when soil sulfate concentration is less than 5 mg kg-1 at planting. In such cases yield increases ranged between 204 and 467 kg ha-1. When soil sulfate test is higher, odds for yield increases from applied S are low, with chances of observing negative responses, too. No relation between PMN and yield response could be found

Agricultura de precisión: ¿Qué es y cuánto se usa en Uruguay?.

La agricultura de precisión involucra un conjunto de estrategias de manejo orientadas hacia un uso más eficiente de los recursos y por tanto contribuye a una intensificación sostenible. Como forma de aportar al conocimiento y perspectivas de esta temática, INIA realizó una encuesta donde releva y analiza el estado desituación y potencialidades de esta estrategia de manejo en los sistemas agrícolas del Uruguay."La agricultura d de precisión es una estrategia de manejo que reúne procesos y analiza datos individuales, temporales y espaciales, que combinados con otra información del sitio apoya la toma de decisiones de manejo de acuerdo a la variabilidad estimada, buscando mejorar la eficiencia de uso de los recursos, la productividad, la calidad, la rentabilidad y últimamente la sostenibilidad de la producción agrícola. International Society of Precision Agriculture, 2018

Metapopulation dynamics of the bog fritillary butterfly: modelling the effect of habitat fragmentation

Population viability analysis (PVA) and metapopulation theory are valuable tools to model the dynamics of spatially structured populations. In this article we used a spatially realistic population dynamic model to simulate the trajectory of a Proclossiana eunomia metapopulation in a network of habitat patches located in the Belgian Ardenne. Sensitivity analysis was used to evaluate the relative influence of the different parameters on the model output. We simulated habitat loss by removing a percentage of the original habitat, proportionally in each habitat patch. Additionally, we evaluated isolation and fragmentation effects by removing and dividing habitat patches from the network, respectively. The model predicted a slow decline of the metapopulation size and occupancy. Extinction risks predicted by the model were highly sensitive to environmental stochasticity and carrying capacity. For a determined level of habitat destruction, the expected lifetime of the metapopulation was highly dependent on the spatial configuration of the landscape. Moreover, when the proportion of removed habitat is above 40% of the original habitat, the loss of whole patches invariably leads to the strongest reduction in metapopulation viability. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved

Ajuste del modelo de erosión WEPP para un Argisol Subéutrico y un Brunosol Éutrico en el Uruguay. [WEPP soil erosion model adjustment for an abruptic argiudoll and a vertic argiudoll in Uruguay].

RESUMEN:Los modelos de estimación de erosión son herramientas útiles para la planificación de sistemas productivos sustentables. El modelo Water Erosion Prediction Project (WEPP) estima erosión laminar y en canalículos, así como la carga y deposición del sedimento, con distribución temporal y espacial. Esto permite estimar no sólo los efectos in situ sino también los efectos fuera del sitio, como ser deposición en cauces de agua, pudiéndose aplicar en estudios ambientales. Si bien este modelo está basado en los procesos físicos que ocurren en el suelo, es preciso realizar ajustes sitio-específicos. El objetivo de este estudio fue ajustar el modelo WEPP, para suelos representativos de la zona agrícola litoral oeste y lomadas del este del Uruguay. Se utilizaron datos de parcelas experimentales de escurrimiento de INIA La Estanzuela y Palo a Pique, y se compararon los valores de erosión estimados por WEPP y USLE/RUSLE con los medidos en términos de promedios anuales. Además se contrastó la erosión estimada con WEPP con la medida a escala anual. WEPP estimó la erosión de ambos sitios con alto nivel de precisión, comparable al de USLE (R2=0,97 y 0,98 respectivamente). El índice Nash-Sutcliffe de 0,92 indica que su desempeño es muy bueno. Para continuar esta línea de investigación resulta necesario realizar medidas de variables físicas del suelo o desarrollar ecuaciones de pedotransferencia alternativas..-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.SUMMARY.Erosion estimation models are helpful tools for planning sustainable agriculture systems. The model Water Erosion Prediction Project (WEPP) estimates rill and interrill erosion, as well as sediment load and deposition, including temporal and spatial distribution. This enables the estimation of both in-site and off-site effects such as deposition in water bodies, making it useful for environmental studies. Although this model is based on the physical processes that occur in the soil, site-specific adjustments are needed. The aim of this study was to adjust the WEPP model for the representative Uruguayan agriculture soils of the West coast and East rolling plains. We used the data base of the runoff plots from INIA La Estanzuela y Palo a Pique, and we compared erosion values estimated with WEPP and those estimated with USLE/RUSLE, in terms of annual means. In addition, erosion estimated with WEPP was compared with the data measured at an annual scale. WEPP estimated erosion with high precision in both sites, comparable to USLE (R2 =0.97 y 0.98 respectively). A Nash-Sutcliffe value of 0.92 indicates a very good performance. To continue this research line, measures of local soil physical variables or the development ofalternative pedotransfer equations will be needed