Climatologia, variabilidade e tendências da precipitação pluvial em Veranópolis, Rio Grande do Sul, Brasil

The objective of this study was to characterize the rainfall climatology in Veranópolis, Rio Grande do Sul, Brazil, through analyses of means, variabilities related to El Niño Southern Oscillation (ENSO), and temporal trends, using a 60-year data series (1956-2015). Descriptive statistics of annual, monthly and seasonal rainfall were used to characterize the rainfall climatology. The differences between seasons, and influence of ENSO were evaluated using analysis of variance and the Duncan’s test. Rainfall trends were evaluated by the Mann Kendall test. The local average annual rainfall is 1,683 mm and the average monthly rainfall is 140 mm, varying from 109 (May) to 182 mm (September). The annual rainfall has high interannual (standard deviation of 327 mm), monthly (60-100 mm) and seasonal (124-183 mm) variabilities, which should be considered in non-irrigated agricultural systems using rainfall as the main source of water supply to plants. Although autumn presents lower average rainfall (346 mm) than the other seasons, its average percentages were similar to the total annual rainfall (21-28%), and the rainfalls are well-distributed in the seasons. Differences between ENSO events occurred in the spring; La Niña years showed lower rainfall (385 mm) than El Niño (549 mm) and neutral (481 mm) years. The annual rainfall tended to increase by 6.3 mm per year (p < 0.01), with increases of 2.5 mm in spring and 1.9 mm in winter (p < 0.10) in the period analyzed.Objetivou-se nesse trabalho caracterizar climaticamente a precipitação pluvial, analisar a influência de eventos El Niño Oscilação Sul (ENOS) e a tendência temporal na série de dados 1956-2015 de Veranópolis, Rio Grande do Sul, Brasil. Para caracterização climática foram definidas estatísticas descritivas da precipitação pluvial anual, mensal e estacional. Para identificação de diferenças entre estações e influência de eventos ENOS, os dados foram submetidos à análise de variância e teste de Duncan. Tendências foram avaliadas pelo teste de Mann Kendall. Os resultados indicaram que a precipitação pluvial anual média é de 1.683 mm e a mensal 140 mm, variando entre 109 (maio) e 182 mm (setembro). Há elevada variabilidade interanual na precipitação pluvial anual (desvio-padrão de 327 mm), mensal (60-100 mm) e estacional (124-183 mm), a qual deve ser considerada especialmente em sistemas agrícolas não irrigados nos quais a chuva é o principal mecanismo de aporte de água às plantas. Embora a precipitação pluvial média do outono (346 mm) seja inferior à das demais estações, os percentuais médios em relação ao total anual são semelhantes (21-28%) e a chuva é bem distribuída nas estações. Diferenças entre eventos ENOS ocorreram na primavera, sendo que chove menos em eventos La Niña (385 mm) do que em El Niño (549 mm) e neutros (481 mm). Há tendência climática de aumento da precipitação pluvial anual em 6,3 mm ao ano (p < 0,01), assim como na primavera (2,5 mm) e inverno (1,9 mm) (p < 0,10) na série analisada

Índice de vegetação por diferença normalizada obtido por sensor remoto de superfície para caracterização do ciclo de videiras no Rio Grande do Sul, Brasil

The normalized difference vegetation index (NDVI) obtained by remote sensing is widely used to monitor annual crops but few studies have investigated its use in perennial fruit crops. The aim of this study was to determine the temporal NDVI profile during grapevine cycle in vineyards established in horizontal training systems. NDVI data were obtained by the ground-based remote sensing Greenseeker in Chardonnay and Cabernet Sauvignon vineyards located in the Serra Gaúcha region, Rio Grande do Sul, Brazil, from September to June in the 2014/2015 and 2015/2016 vegetative seasons. The grapevine canopies were managed in horizontal training systems (T-trellis and Y-trellis). The results indicated that the temporal NDVI values varied during the grapevine cycle (0.33 to 0.85), reflecting the changing in vigor and biomass accumulation that resulted from the phenological stages and management practices. The temporal NDVI profiles were similar to both horizontal training systems. The NDVI values were higher throughout the cycle for Cabernet Sauvignon compared to Chardonnay indicating Cabernet Sauvignon as the cultivar with greater vegetative vigor. The NDVI obtained by ground-based remote sensing is a fast and non-destructive tool to monitor and characterize the canopy in real time, compiling into a single data several parameters related to vine development, like meteorological conditions and management practices that are difficult to be quantified together.O índice de vegetação por diferença normalizada (NDVI), obtido por sensoriamento remoto, tem sido amplamente empregado no monitoramento de culturas agrícolas produtoras de grãos, porém poucos são os estudos em fruticultura. O objetivo deste trabalho foi caracterizar a evolução temporal do NDVI obtido por sensor remoto de superfície ao longo do ciclo de videiras em sistemas horizontais de condução do dossel vegetativo. Dados de NDVI foram obtidos com sensor remoto Greenseeker em vinhedos na região da Serra Gaúcha, Rio Grande do Sul, Brasil, de setembro a junho nas safras 2014/2015 e 2015/2016. Os vinhedos das cultivares Chardonnay e Cabernet Sauvignon eram conduzidos em sistema horizontal (latada e lira). Os resultados indicaram que houve variabilidade temporal do NDVI ao longo do ciclo (de 0,33 a 0,85), a qual refletiu as alterações no acúmulo de biomassa e vigor vegetativo decorrentes das principais etapas fenológicas e práticas de manejo. A evolução temporal do NDVI foi semelhante nos sistemas latada e lira, ambos caracterizados pela condução horizontal do dossel vegetativo. Os valores de NDVI para ‘Cabernet Sauvignon’ foram superiores aos de ‘Chardonnay’ ao longo do ciclo, independe da safra avaliada e do sistema de condução, indicando ‘Cabernet Sauvignon’ como a cultivar de maior vigor vegetativo. O NDVI, obtido por sensor remoto de superfície, é uma forma rápida e não destrutiva de monitoramento e caracterização do dossel vegetativo em tempo real, compilando em uma única informação o desenvolvimento da videira, o qual é resultado de diversos fatores, edafo-climáticos e de manejo, dificilmente quantificados conjuntamente

Daily Faecal Excretion of Alkane \u3cem\u3eC\u3csub\u3e32\u3c/sub\u3e\u3c/em\u3e in Beef Cattle Females Grazing Natural Grasslands in Southern Brazil and in Uruguay

The n-alkane technique is accepted as an appropriate method to estimate herbage intake by grazing ruminants. This method reinforces issues similar to those raised by other methods based on markers such as the effect of carrier matrix or dosing method and frequency on the excretion kinetics of the dosed n-alkanes (Dove et al. 2002; Molina et al. 2004, Oliván et al. 2007). The time of dosage needed to reach the dynamical equilibrium between the concentrations of alkanes in the diet and in the faeces of ruminants is still unclear for the natural grassland environments. The aim of this study was to determine the appropriate timing of oral administration of alkane C32 to estimate herbage intake in beef heifers on natural grassland environments

What Factors Control the Crude Protein Content Variation of a Basaltic “Campos” Native Grassland of South America?

Native grasslands are the main source of food for livestock in the Campos region of South America. These forage resources are heterogeneous in species composition, grazing management, and soil fertility within a context of variable climate, all of which are factors that affect forage crude protein content over time and space. Despite the importance of protein in livestock nutrition, there is a gap in the knowledge of how fertilisation, sward height, and soil water availability influence the crude protein content of these grasslands. We used data from a long-term fertilisation experiment to construct a structural model aiming to identify the main factors influencing forage crude protein content of a basaltic native grassland in northern Uruguay. The structural model revealed that both fertilisation and the increase in soil water availability (through the improvement of the nitrogen content of green leaves) are the main pathways by which forage crude protein content increases. This new approach (which identifies and quantifies the main factors that drive forage crude protein content of native grasslands) could be used to support prediction models for forage protein content in order to improve grazing livestock nutrition of Campos native grasslands.EEA Concepción del UruguayFil: Núñez, Laura. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; UruguayFil: Hirigoyen, Andrés. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Forestal; UruguayFil: Durante, Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; ArgentinaFil: Durante, Martin. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; UruguayFil: Arroyo, José María. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA La Estanzuela. Programa Pasturas y Forrajes; UruguayFil: Cazzuli, Fiorella. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; UruguayFil: Bremm, Carolina. Universidade Federal de Rio Grande do Sul.Faculdade de Agronomia. Departamento de Plantas Forrageiras e Agrometeorologia. Programa de Pós-Graduação em Zootecnia; BrasilFil: Jaurena, Martín. Instituto Nacional de Investigación Agropecuaria (INIA). Estación Experimental INIA Tacuarembó. Programa Pasturas y Forrajes; Urugua

Using temporal NDVI/MODIS profiles for inferences on the crop soybean calendar

Um dos maiores desafios para a modelagem de rendimentos de grãos, no contexto das estimativas de safras feitas de forma operacional para grandes áreas, está relacionado à identificação no tempo dos períodos em que as culturas anuais apresentam maior suscetibilidade a estresses ambientais. Para a cultura da soja, cultivada no período de primavera-verão no sul do Brasil, o principal fator de risco é a ocorrência de estresse hídrico no florescimento e enchimento de grãos. Esses subperíodos ocorrem em períodos distintos ao longo da região de produção como consequência de práticas de manejo diferenciadas dos produtores. Este trabalho teve como objetivo relacionar o calendário agrícola da cultura da soja a perfis temporais do índice de vegetação por diferença normalizada (NDVI/MODIS), com intuito de apresentar/validar uma tecnologia de baixo custo e adequada acurácia para fins de monitoramento e previsão de safras. Para tanto, foram analisados os dados de calendário agrícola (subperíodos de floração, enchimento de grãos e maturação) da cultura da soja em regionais da EMATER (RS) e imagens NDVI do sensor MODIS. Os resultados mostraram que os perfis temporais de NDVI permitem acompanhar a evolução temporal da biomassa da cultura da soja e determinar a ocorrência dos subperíodos do ciclo. As diferenças no valor do NDVI entre safras, regionais e subperíodos do ciclo da cultura demonstram a sensibilidade deste índice em detectar as respostas das plantas de soja às condições ambientais. Como consequência dos dados de NDVI serem gerados a partir das imagens MODIS, é possível a espacialização da informação acerca dos subperíodos para todas as safras e em todo o Estado, o que permite maior detalhamento temporal e espacial comparativamente à atual disponibilidade dos dados.A major challenge for grain yield modeling in the context of estimates made operationally for large areas is related to the identification of periods in which annual crops show greater susceptibility to environmental stress. For soybean grown in the spring-summer period in southern Brazil, the main risk factor is the occurrence of water stress during flowering and grain filling. These subperiods occur at different times across the production region due to differences in management practices of each farmer. This study aimed to relate the soybean crop calendar to the temporal profiles of normalized difference vegetation index (NDVI/MODIS), in order to present/validate a low cost technology with adequate accuracy for crop monitoring and harvest prediction. Thus, we analyzed data from soybean crop calendar (subperiods of flowering, grain filling and maturation) from EMATER (RS) regions and NDVI MODIS images. The NDVI temporal profiles allow monitoring the development of the soybean crop biomass and determining the occurrence of subperiods. Differences in NDVI values between harvests, regions and subperiods demonstrate the sensitivity of this index in detecting the responses of soybean plants to environmental conditions. Because NDVI data are generated from MODIS images, it is possible to create maps with information about the subperiods for all harvests and throughout the State, which enables greater temporal and spatial details compared to data currently available

Sward Management Targets in Natural Grasslands of Southern Brazil

The relationship between environment, plant and animal is one of the most important focuses in the ecological and productive context of natural grasslands. The limited knowledge of the complexity of this environment can lead to inappropriate management strategies, determining degradation, biodiversity and productivity losses. This study is based on the concept that the best way to conserve natural grasslands is through adequate management targets. This study aimed to identify sward management targets that maximize productivity in natural grasslands of Southern Brazil

Comparing grazing intensities in crop-livestock systems with STICS

editorial reviewe

Diagnóstico do extrativismo, processamento e comercialização de produtos oriundos de butiazais no Rio Grande do Sul

Brazil is home to 37 genera of palm trees that participate in the ecologicalbalance of different biomes. In the southern region there is a genus of palm tree, Butia spp., which has eight species, and is threatened with extinction. Butiá extractivism, through management that allows its rational exploration, can be an alternative to encourage its preservation. The aim of this article is to present a diagnosis of the extraction of butia plant in the state of Rio Grande do Sul, providing systematized data about this reality. The first stage of the research consisted of a survey on thenumber of properties that have areas of butia groves throughout the state, through Emater-RS. Based on these data, it was possible to define a statistically representative sample, which culminated in interviews with 105 rural producers. The results show that there are about 5,300 hectares of butiá in rural properties in the state, more than 400 thousand plants distributed in 28 thousand rural establishments. The number of families that use some product from the butiazal is more than 16 thousand. Comparing the use of butiazal products among groups of farmers according to the type of management, we found that the practice of extractivism is more widespread among producers who adopt organic management. The main obstacle to developing butiá extractivism is the lack of a processing structure; while the main advantages are the low demand for inputs and ease of handling, in the opinion of rural producers.O Brasil abriga 37 gêneros de palmeiras que participam do equilíbrio ecológico de diferentes biomas. Na região sul há um gênero de palmeira, o Butia spp., que conta com oito espécies e está ameaçada de extinção. O extrativismo do butiá, através de manejo que permita sua exploração racional, pode ser uma alternativa para estimular sua conservação. O objetivo do artigo é apresentarum diagnóstico sobre o extrativismo do butiazeiro no estado do Rio Grande do Sul, fornecendo dados sistematizados acerca dessa realidade em nível estadual. A primeira etapa da pesquisa consistiu em umlevantamento sobre a quantidade de propriedades que possuem áreas de butiazais em todo estado, através daEmater-RS. A partir desses dados,foi possível definir uma amostra estatisticamente representativa, que culminou em entrevistas com105 produtores rurais. Os resultados mostram que há cerca de 5.300hectares de butiazais em propriedades rurais noestado, mais de 400 mil plantas distribuídas em 28 mil estabelecimentos rurais. O número de famílias que utilizam algum produto do butiazalé de mais de 16 mil. Comparando a utilização dos produtos do butiazal entre grupos de agricultores segundoo tipo de manejo, constatamos que a prática do extrativismo é mais difundida entre os produtores que adotam o manejo orgânico. O principal entrave para desenvolver o extrativismo de butiá é a falta de estrutura de processamento; enquanto as principais vantagens são a baixa demanda de insumos e a facilidade no manejo, na opinião dos produtores rurais

Integrated crop and livestock systems increase both climate change adaptation and mitigation capacities.

peer reviewedIntegrated crop-livestock systems (ICLS) are proposed as key solutions to the various challenges posed to present-day agriculture which must guarantee high and stable yields while minimizing its impacts on the environment. Yet the complex relationships between crops, grasslands and animals on which they rely demand careful and precise management. In this study, from a 18-year ICLS field experiment in Brazil, that consists in annual no-till soybean-pastures grazed by beef cattle, we investigated the impacts of contrasted pastures grazing intensities (defined by sward heights of 10, 20, 30 and 40 cm, plus an ungrazed treatment) on the agroecosystem productivity and soil organic carbon (SOC) under both historical and future (2040-2070, RCP8.5) climatic conditions. We used an innovative methodology to model the ICLS with the STICS soil-crop model, which was validated with field observations. Results showed that the total system production increased along with grazing intensity because of higher stocking rates and subsequent live weight gains. Moderate and light grazing intensities (30 and 40 cm sward heights) resulted in the largest increase in SOC over the 18-year period, with all ICLS treatments leading to greater SOC contents than the ungrazed treatment. When facing climate change under future conditions, all treatments increased in productivity due to the CO2 fertilization effect and the increases in organic amendments that result from the larger stocking rate allowed by the increased pasture carrying capacity. Moderate grazing resulted in the most significant enhancements in productivity and SOC levels. These improvements were accompanied by increased resistance to both moderate and extreme climatic events, benefiting herbage production and live weight gain. Globally, our results show that adding a trophic level (i.e. herbivores) into cropping systems, provided that their carrying capacities are respected, proved to increase their ability to withstand climate change and to contribute to its mitigation