Tillage system and planting date effects on corn (Zea mays L.) and soybean (Glycine max L.) yield

Although tillage systems produce different soil conditions, which result in different ideal planting dates, and crops respond to planting date, most of tillage research is conducted based on a calendar date. If a tillage system by planting date interaction exists, most of the planting date recommendations based on calendar date research could change. Different authors have modified surface residue distribution in an attempt to achieve optimal soil conditions for crop growth in the row zone while maintaining optimum soil conservation conditions in the mulched interrow zone. A reasonable goal for soil management involves identifying the level of soil and residue disturbance necessary to optimize soil environmental conditions for the corn plant and residue cover for soil conservation. In order to design a tillage system that produces a residue-free band-width based on site-specific soil properties and crop needs, the use of a model to capture the effect of surface residue management, soil non-uniformities (i.e., row zone tillage), and tillage is necessary. Considering a potential tillage by planting date interaction and site-specific strip tillage opportunities, this thesis has the following objectives. The first objective is to test the performance of strip tillage, no tillage, and conventional tillage when each system is planted on the day that optimum soil temperature and water conditions for planting are reached for each system. The second objective is to conduct a soil temperature sensitivity analysis to residue-free band-width, and tillage depth with strip tillage using a model that couples water and heat transport in non-uniform soils. In a two-year study on a poorly drained soil tillage system, effects on corn yield were not detected when preestablished soil temperature and water content criteria were used to determine the day of planting each system. On the other hand, planting date has an effect on corn yield. A tillage system by planting date interaction was detected for soybean yield in one of two years, when drought conditions existed during the second half of July and August. Soil temperature, soil water content, and matric potential were most sensitive to changes in residue-free band-width at 0.05-m in both soils studied

Strip Till, No-Till and Conventional Tillage Comparisons - Does Planting Date Affect Results?

Numerous tillage studies have been conducted in Iowa, the Midwest, and throughout the U.S. with a wide range of results. The tillage system that results in the highest yield depends on several factors including soil type and weather during the study Generally, systems with little soil disturbance are favored on coarser textured soils and/or in drier years (Eckert 1987; Beyaert et al 2002). For soil and water conservation purposes, as well as for economic reasons, extending successful use of no-till or similar systems to finer textured soils seems advantageous

Sea-level trends along freshwater and seawater mixing in the uruguayan Rio de la Plata estuary and Atlantic Ocean coast

Sea level is rising worldwide with local differences due to global and regional drivers. This article analyses yearly freshwater and sea level trends and fluctuations during the mixing of fresh- and sea-water along the Uruguayan coast of the Rio de la Plata River estuary and the Atlantic coast from 1961 to 2014. The global and regional drivers as well as local co-variables are described, classified in nine discrete classes and inter-correlated. Despite the observed increasing trends, local sea level rises (SLR) are not well correlated with global SLR except at the estuarine-ocean boundary (Punta del Este station). Freshwater inflow, which variability often coincides with Oceanic El Niño-La Niña (ONI-ENSO) events, is the first descriptor of sea level fluctuations and outliers all along the coast, particularly at Punta del Este. Local SLR roughly follows the overall global trend with periods of acceleration and stabilization often coinciding with ENSO event

Soil quality impacts of current South American agricultural practices

Increasing global demand for oil seeds and cereals during the past 50 years has caused an expansion in the cultivated areas and resulted in major soil management and crop production changes throughout Bolivia, Paraguay, Uruguay, Argentina and southern Brazil. Unprecedented adoption of no-tillage as well as improved soil fertility and plant genetics have increased yields, but the use of purchased inputs, monocropping i.e., continuous soybean (Glycine max (L.) Merr.), and marginal land cultivation have also increased. These changes have significantly altered the global food and feed supply role of these countries, but they have also resulted in various levels of soil degradation through wind and water erosion, soil compaction, soil organic matter (SOM) depletion, and nutrient losses. Sustainability is dependent upon local interactions between soil, climate, landscape characteristics, and production systems. This review examines the region’s current soil and crop conditions and summarizes several research studies designed to reduce or prevent soil degradation. Although the region has both environmental and soil resources that can sustain current agricultural production levels, increasing population, greater urbanization, and more available income will continue to increase the pressure on South American croplands. A better understanding of regional soil differences and quantifying potential consequences of current production practices on various soil resources is needed to ensure that scientific, educational, and regulatory programs result in land management recommendations that support intensification of agriculture without additional soil degradation or other unintended environmental consequences.EEA ParanáFil: Wingeyer, Ana Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; ArgentinaFil: Amado, Telmo Jorge Carneiro. Universidade Federal de Santa Maria. Centro de Ciências Rurais; BrasilFil: Pérez Bidegain, Mario. Universidad de la República. Facultad de Agronomía; UruguayFil: Studdert, Guillermo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Perdomo Varela, Carlos Honorio. Universidad de la República. Facultad de Agronomía; UruguayFil: García, Fernando O. International Plant Nutrition Institute. Americas and Oceania Group. Latin America - Southern Cone; ArgentinaFil: Karlen, Douglas L. United States. Department of Agriculture. Agricultural Research Service; Estados Unido

Tendencias recientes de las precipitaciones e impactos asociados con ENSO en la cuenca del Río de la Plata

La evolución temporal de la precipitación anual sobre la cuenca del Río de la Plata (RdP) durante el periodo 1971-2015, evidencia un incremento aproximado de 40 mm y una alta variabilidad interanual, particularmente influenciada por El Niño. Se destacan los años 2002 y 2014 como los más húmedos, superando los 1.700 mm/año, mientras que 1999 y 2008 se destacan como los años más secos, coincidiendo con fases frías del ENSO. La precipitación anual ha aumentado en el promedio de la cuenca (alrededor de 40 mm más en la actualidad que en la década de 1970). Sin embargo, al norte de la cuenca se observa disminución. El índice de intensidad diaria de precipitación (SDII) ha aumentado, aproximadamente 3 mm respecto a los años setenta. Las fuertes tasas de tendencia positiva de lluvia correspondientes a días húmedos para RR>99 percentil (RR99p) son evidentes en la mayor parte de la cuenca. La fuerte tendencia incremental de la precipitación anual parece estar más relacionada con la intensificación de los eventos extremos. Se sugiere que la cuenca se comporta como más húmeda probablemente asociada a eventos de lluvias extremas, que con una mayor frecuencia de días húmedos. Se registraron varias inundaciones, muchas de ellas asociadas a fase cálida del ENSO, que han impactado en la población, debido en gran medida a la vulnerabilidad asociada a la exposición.The evolution of the annual precipitation over the Rio de la Plata basin (RdP) during the period 1971-2015, shows an approximate increase of 40 mm and a high interannual variability, particularly influenced by El Niño. The years 2002 and 2014 are the most humid, exceeding 1,700 mm / year, while 1999 and 2008 stand out as drier years, coinciding with the cold phase of ENSO. Annual precipitation is increased in the basin average (about 40 mm more at present than in the 1970s). However, to the north of the basin there is a decrease. The daily precipitation intensity index (SDII) has increased, approximately 3 mm from the 1970s. The strong positive rainfall rates corresponding to wet days for RR> 99 percentile (RR99p) are evident in most of the basin. The strong incremental trend of annual precipitation seems to be more related to the intensification of extreme events. It is suggested that the basin behaves as wetter probably associated with events of extreme rains, than with a greater frequency of wet days. There were several floods, many associated with El Niño, which have impacted the population, largely due to the vulnerability associated with exposure

Grid Computing for Climate Processing on South America

O projeto LAG-Clima quer estabelecer um ambiente de computação em grade de processamento e compartilhamento de dados. O objetivo é manter uma rede de interconexão entre instituições na América do Sul para previsão climática em meso-escala e disponibilizar dados. Plataforma de softwares: BRAMS (código meteorológico de meso-escala), OurGri

Avaliação de mudanças na freqüência de sistemas frontais sobre o Sul da America do sul em projeções do clima futuro

The frequency of frontal systems reaching the south of South America is compared with reanalysis, NCEP/NCAR, and results of GFDL and Hadley models for the future climate A2 scenario. For the present climate the analyzed period was 1961-1990 and for future projections, 2081-2100, from May to September. Three regions were analyzed to identify the frontal systems, in areas of Brazil, Uruguay, Paraguay and Argentina. The following criteria were used: increase of sea surface pressure, reduction of the temperature and change of the meridional wind at 850hPa, in two consecutive days. Selected cases with temperature drop above 5 degrees, considered the most intense, were also analyzed. For the present climate it was observed that the models simulated well the synoptic characteristics of frontal systems. However, when comparing the frequency of frontal occurrence between reanalysis data and models simulations, the GFDL and Hadley models overestimated their numbers. The Hadley model overestimates further more than the NCEP and GFDL in present climate. The positive trend observed in area 3 from NCEP reanalysis is not simulated by the models. When the most intense systems are selected, the GFDL model shows higher overestimation in number of frontal systems. Both models indicate an increase of frontal systems frequency in the future in the three areas, although less in area 3.The frequency of frontal systems reaching the south of South America is compared with reanalysis NCEP/NCAR and results of GFDL and Hadley models for the future climate. Three regions were analyzed to identify the frontal systems, in areas of Brazil, Uruguay, Paraguay and Argentina. The following criteria were used: increase of sea surface pressure, reduction of the temperature and change of the meridional wind at 850hPa, in two consecutive days. Selected cases with temperature drop above five degrees, considered the most intense, were also analyzed. For the present climate it was observed that the models simulated well the synoptic characteristics of frontal systems. However, when comparing the frequency of frontal occurrence between reanalysis data and models simulations, the GFDL and Hadley models overestimated their numbers. The Hadley model overestimates further more than the NCEP and GFDL in present climate. The positive trend observed in area 3 (65ºW-60ºW, 33ºS-38ºS) from NCEP reanalysis is not simulated by the models. When the most intense systems are selected, the GFDL model shows higher overestimation in number of frontal systems. Both models indicate an increase of frontal systems frequency in future in the three areas, although less in area 3.Fil: Martins Andrade, Kelen. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; BrasilFil: Muller, Gabriela Viviana. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Cavalcanti, Iracema F .A.. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; BrasilFil: Fernández Long, María Elena. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Bidegain, Mario. Universidad de la República; UruguayFil: Berri, Guillermo Jorge. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Climate Risks and Reasons for Concern along the Uruguayan Coast of the Rio de la Plata Estuary

The Uruguayan coast of the Río de la Plata river estuary (RdlP) is 300 km long. It encompasses an inner tidal river and a middle and an outer estuary. The RdlP is a micro-tidal system dominated by river inflow from the Paraná and Uruguay rivers and southern winds with increasingly frequent wind-induced storm surges impacting the coast. The El Niño-Southern Oscillation influences the river inflow, prevailing winds, water/sea level and beach erosion. First, we focus on the IPCC Reasons for Concern (RFC) about the trends of climate risks threatening the Uruguayan coast. The trends and maxima of air temperature, water/sea levels and river inflow in three coastal stations from 1980 to 2019 show temporal changes attributable to climate change and El Niño-Southern Oscillation (ENSO). The occurrence, evolution and Montecarlo simulations of return periods of the yearly river flow and sea level height maxima provide metrics of RFC to categorise the climate risks from past to projected future and the level of risk from undetectable to very high. Then, we summarise some current and expected climate risks and present the current adaptation framework and some expected impacts. The RFC has increased, reaching moderate to high-risk levels

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes