Search

The owlet moths (Lepidoptera: Noctuidae) Anicla infecta (Ochsenheimer 1816), Elaphria agrotina (Guenee 1852) and Spodoptera frugiperda (J.E. Smith 1797) occur in the entire American continent. These polyphagous moths have a preference for grasses, and have different biological habits. In this study, the populations of these three species were evaluated monthly with light traps in the Brazilian Savannah, ranging a span of four crop seasons (from July, 2013 to June, 2017). The population data were analyzed and correlated with the meteorological variables: maximum temperature, minimum temperature, relative humidity and precipitation. A total of 4719 individuals were collected in the following percentages: A. infecta (n = 459; 9.73%), E. agrotina (n = 1809; 38.33%) and S. frugiperda (n = 2451; (51.94%). The abundance of all species went down from the first crop season (2013/2014) to the third (2015/2016). In the fourth crop season (2016/2017), the populations of A. infecta and E. agrotina stabilized, but the abundance of S. frugiperda experienced further decrease. The numbers of individuals of three species declined when precipitation was much above (crop season 2014/2015) and below (crop season 2015/2016) than expected by the climatological normal. There were significant, but different degrees of correlation, between the meteorological factors and the ONI index (Oceanic Nino Index - indicator for monitoring El Nino-Southern Oscillation or “ENSO”) with respect to monthly population variations. The results are discussed in accordance with principles of the Integrated Pest Management (IPM) in mind, given the continental distribution and agricultural importance of the three owlet moth species studied.

We calibrated the crop model STICS and used it in a simulation experiment to assess the effect of no-tillage cropping systems, with and without millet as cover crop (NTM and NT), on the water-limited yield of maize, its inter-annual variability, water runoff and drainage below the root zone, compared to conventional tillage-based cropping systems (CT). We ran simulations for two contrasting climates in the Brazilian Cerrado, Goiânia with 1600 mm of annual rain and Barreiras with 1160 mm, using a series of historical weather data and considering two soil types with different soil water storage capacities (i.e. different maximum rooting depths of 90 and 180 cm). We identified the best suitable sowing windows based on agronomic (yield and yield variability) and environmental (runoff and drainage) performances of the cropping systems. Compared to CT, NT and NTM systems increased water-limited maize grain yield and its stability. For example, for the simulations with 90 cm set as maximum rooting depth, grain yields for CT, NT and NTM, averaged over all sowing dates, were 3.41, 4.35 and 4.28 t ha−1 in Goiâna, and 7.02, 7.67 and 7.5 t ha−1 in Barreiras. No-tillage systems markedly decreased water runoff and hence erosion risks. For example, simulated runoff was on average 4% of the annual rain for NT and NTM against 13% for CT at both locations. In contrast, no-tillage systems increased water drainage below the rooting zone, hence with risks of increased nutrient leaching. For example, for the 90 cm maximum rooting depth, simulated drainage was 48% and 41% of the annual rain for NT and NTM against 32% for CT in Goiânia, and 29% and 26% against 17% in Barreiras. Reconciling the objective of maximizing yield and its stability with that of minimizing both water runoff and drainage was only achieved under no-tillage with millet as cover crop (NTM) for a very narrow range of sowing dates. Sowing all fields of the farm within a narrow optimal window requires, however, important investment in machinery and preferential allocation of available farm resources for sowing activities at the start of the cropping season. This must be weighed against other farm activities.

The first detection of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) in Brazil pointed to a gloomy future for South American agriculture in the 2012/2013 harvest, and insecticide sales increased exponentially during 2013 and 2014. However, after this outbreak, the population of this insect returned to manageable levels. This study documents data on H. armigera moth collection using light traps during the outbreak in two locations: (a) western region of the state of Bahia, including population levels of H. armigera and main noctuid pests during the big outbreak (February and March 2013); (b) Federal District, including monthly data for five growing seasons (July 2012–June 2017). During the outbreak, an average of 527.3 moths were collected per trap (cotton crop, March) in the western region of Bahia each night, while the maximum average in the Federal District was 75.4 moths (January). The number of moths decreased in the following growing seasons, and in October 2016, the maximum number was 2.8 moths per trap. Aspects related to the variations of H. armigera and Helicoverpa zea (Boddie) populations, including the study of phenology and relationship with climatic factors and Oceanic Nino Index, were analyzed and discussed. All aspects are approached to contribute to the management of lepidopteran pests, especially H. armigera, in the productive systems of the Brazilian Cerrado.

Relay intercropping of maize with fodder crops is a promising option for sustainable intensification of dairy small-scale farms in the Cerrado of Brazil. Twenty-six intercropping trials were conducted on farmers’ fields with the following experimental treatments: sole maize crop cropping (MS), maize-Brachiaria intercropping (MB) and maize-pigeon pea intercropping (MP). The trials were managed by the farmers, i.e. choice of conventional tillage (CT) versus no-tillage (NT), sowing dates, fertilization and weed control. Maize grain yield varied strongly across the farmer fields, from 100 to 5900 kg ha−1 in the MS treatment, 500 to 6900 kg ha−1 in MP and 300 to 5500 kg ha−1 in MB. Intercropping did not significantly affect maize grain yields under NT, but yields were reduced under CT in one out of two seasons. Maize yields in the intercropped systems were also higher under NT than CT. Total biomass productivity was significantly higher in the maize-fodder than in the sole maize system. An increased interval between sowing of maize and fodder crop significantly reduced the fodder crop biomass. Relay intercropping, especially in combination with NT, is a promising option if crop calendars and fertilization are properly managed by farmers to reduce interspecific competition between the maize and fodder crop.

Conservation agriculture (CA) is recognized as a promising crop management strategy for sustainable agricultural intensification. The objective of this study was to evaluate CA cropping systems for rainfed maize as an alternative to the traditional tillage-based cropping systems (CT) in the context of family farms, using a multi-criteria model that represents the point of view of farmers. Farmers considered several aspects for evaluating the cropping systems, thatwere systematized in the model through five criteria (with sub-criteria): (a) costs; (b) yield; (c) labour; (d) human health and environment; and (e) production risks. CA did not differ from CT for the 'costs' criterion but was superior for the 'yield' and 'labour' criteria. In contrast, CT obtained better ratings for the criteria 'human health and environment' and 'production risks'. Considering all criteria, CA was better appraised than CT. However, a new local policy measure that subsidizes the hiring of mechanized tillage services overturns this outcome, indicating the importance of exogenous factors. Overall, the participatory processes in building the model allowed us to better understand the reasons of adoption or non-adoption of CA by small-scale farmers in the tropics.

A agricultura é uma atividade de risco e incerteza. O Zoneamento Agrícola de Risco Climático (ZARC) indica o que, onde e quando plantar para fugir dos eventos climáticos. O objetivo do trabalho foi comparar duas metodologias para o zoneamento agrícola de risco climático da soja (Glycine max (L) Merrill) no Bioma Cerrado. Utilizou-se o Índice de Satisfação da Necessidade de Água (ISNA) considerando às fases fenológicas críticas ao déficit hídrico: Fase I (germinação e emergência) e Fase III (floração e enchimento de grãos). Na primeira abordagem considerou-se a fase III. Na segunda abordagem consideraram-se as fases I e III. Utilizou-se o programa SARRAZON para a simulação do balanço hídrico. A zona de baixo risco climático correspondeu ao ISNA > 0,50 na fase I; e, o ISNA> 0,65 na fase III. Para fins de comparação considerou-se a época de semeadura, porcentagem das áreas de risco e quantidade de municípios recomendados. Na segunda metodologia, as zonas de baixo risco foram menores. A soja foi recomendada em solos com maior capacidade de água disponível. As áreas de alto risco situaram-se na transição entre os biomas Caatinga e Pantanal. Esse estudo orienta o risco agroclimático da soja e subsidia políticas públicas no Cerrado.Palavras-chave: agroclimatologia; gestão ambiental; política agrícola; planejamento ambiental. CLIMATIC RISK ZONING METHODOLOGIES FOR SOYBEAN CULTIVATION IN THE CERRADO BIOME ABSTRACT: Agriculture is an activity of risk and uncertainty. Agricultural Climate Risk Zoning (ZARC) indicates what, where and when to plant to escape climate events. The objective of this work was to compare two methodologies for agricultural climate risk zoning of soybean (Glycine max (L) Merrill) in the Cerrado Biome. The Water Requirement Satisfaction Index (WRSI) was used considering the phenological phases critical to water deficit: Phase I (germination and emergence) and Phase III (flowering and grain filling). In the first approach, phase III was considered. In the second approach, phases I and III were considered. The SARRAZON program was used to simulate water balance. The low climate risk zone corresponded to WRSI > 0.50 in phase I; and WRSI > 0.65 in phase III. For comparison purposes, the sowing time, percentage of risk areas and number of recommended municipalities were considered. In the second methodology, the low risk zones were smaller. Soybean has been recommended in soils with the highest available water capacity. The high-risk areas were in the transition between the Caatinga and Pantanal biomes. This study guides soy agroclimatic risk and subsidizes public policies in the Cerrado.Keywords: agroclimatology; environmental management; agricultural policy; environmental planning.

Este trabalho teve como principal objetivo apresentar um método de zoneamento pedoclimático para o cultivo do milho consorciado com a braquiária que considere os componentes de risco climático, do potencial edáfico e de restrições territoriais. Com o uso de ferramentas de geoprocessamento, foram subtraídas do mapa base do estado, as unidades de conservação, os espelhos d´água, declividades superiores a 45% e as informações de solos não recomendadas para o desenvolvimento agrícola do Estado. O cálculo da reserva útil de água dos solos foi realizado a partir da reclassificação do mapa de solos em função da textura. As datas de semeadura com menor risco climático foram calculadas por meio do balanço hídrico das culturas. Da área total de Cerrado do estado de Goiás (329.581 km²), 50,13%, ou 165.218 km² não são considerados áreas agricultáveis, enquanto que 49,87%, ou 164.363 km², são agricultáveis. Essa abordagem permitiu identificar áreas mais apropriadas para o desenvolvimento agrícola do estado de Goiás e datas de semeadura com menor risco climático para a semeadura do consórcio. Esse estudo pode ajudar no desenvolvimento de políticas públicas que objetivem a sustentabilidade da agricultura a partir da adequação das datas de semeadura com menor risco climático das culturas com a proteção ambiental do Estado.

O presente trabalho teve como objetivo determinar a produtividade agricola e a qualidade tecnologica do caldo das variedades da cana-de-acucar, submetidas a diferentes regimes hidricos. O delineamento experimental foi em blocos ao acaso com tres repeticoes em parcelas subdivididas, com tres variedades RB855156, RB835486 e RB867515 (parcela), e sete regimes hidricos correspondendo a 0, 7, 17, 36, 46, 75 e 100% da ETc (subparcela). Foram avaliadas as caracteristicas de producao: comprimento do entreno (CE), peso do colmo (PC), numero de perfilhos por hectare e produtividade; e tecnologicos do caldo: oBrix do caldo, Pol do caldo (Teor de sacarose), pureza (PZA), AR (teor de acucares redutores do caldo), ARC (acucares redutores da cana), fibras, Pol da cana (PCC), acucares totais recuperaveis (ATR) e o valor da megagrama da cana (VMgC). O maximo de produtividade da cana-de-acucar foi de 182,31 Mg ha-1 registrado com irrigacao equivalente a 69,01% da ETc; A cana-de-acucar cultivada com irrigacao equivalente a 75% da ETc nao proporcionou diferenca significativa para a qualidade industrial das variedades testadas em relacao ao cultivo em sequeiro (0% da ETc). Nao houve diferenca significativa para os valores do teor de acucares redutores (AR), acucares redutores da cana (ARC) e a pureza do caldo (PZA) entre as variedades. Palavras-chave: Saccharum spp., estresse hidrico, niveis de irrigacao. PRODUCTIVITY AND QUALITY OF THIRD RATOON SUGARCANE VARIETIES UNDER VARIABLE HYDROLOGICAL REGIME ABSTRACT This work aimed to determine the agricultural productivity and the technological quality of the juice of the sugarcane varieties, which were submitted to different hydrological regimes. The experimental design was made in randomized blocks with three repetitions in subdivided plots, with three varieties: RB855156, RB835486 and RB867515 (plot), and seven hydrological regimes corresponding to 0, 7, 17, 36, 46, 75 and 100% of ETc (subplot). The following production characteristics were evaluated: length of internode (LI), stem weight (SW), number of tillers per hectare and productivity; and technological components of the juice: oBrix of the juice, Pol of the juice (sucrose levels), purity (PTY), RS (amount of reducing sugars of the juice), RSC (reducing sugars of the sugarcane plant), fibers, Pol of the sugarcane plant (CPP), total retrievable sugars (TRS) and the value of the sugarcane megagram (Mg). The maximum productivity of sugarcane was 182.31 Mg ha-1, which was registered with irrigation equivalent to 69.01% of ETc. The sugarcane cultivated with irrigation equivalent to 75% of ETc did not provide significant difference for the industrial quality of varieties tested in relation to the non-irrigated cultivation (0% of ETc). There was no significant difference for the values of reducing sugars (RS), the reducing sugars of the sugarcane plant (RSC) and the juice purity (PTY) among varieties . Keywords: Saccharum spp., water stress, levels of irrigation. DOI: http://dx.doi.org/10.14583/2318-7670.v04n01a08

Climatic risk zoning allows the identification of areas of low risk of reduced crop productivity due to climatic events. In Brazil, losses to agriculture due to climate are mainly caused by drought. The objective of this research was to determine areas of low climatic risk for corn and palisade grass cultivated in integrated crop-livestock systems in Sao Paulo state. Corn varieties characterized by a 120-day growing cycle and soil with three different water holding capacities (sandy, medium and clayey soils) were considered. A daily water balance model was used to simulate planting dates between September and December. The water requirement satisfaction index (WRSI) was calculated for critical phenological phases of both cultures (germination, emergence and tillering of palisade grass and flowering and grain filling of corn). The WRSI values, calculated for a minimum frequency of 80%, were located spatially using the SPRING v. 5.1 geographic information system and the most favorable periods for sowing in different areas were determined. The results showed that there are areas of low climatic risk for cultivation of corn and palisade grass in integrated crop-livestock production systems in Sao Paulo state. Although climatic risk in these areas also depends on soil type, the most favorable period for planting is between October and November.

Correspondance: marc.corbeels@cirad.fr; International audience; In the Cerrado region of Brazil conventional soybean monoculture is since the 1980s being replaced by direct seeding mulch-based cropping (DMC) with two crops per year and absence of tillage practices. The objective of this study was to assess the long-term impact of DMC on soil organic matter accumulation and nitrogen (N) mineralization. Measurements of soil organic carbon (C) content, soil total N content and soil N mineralization, both under laboratory conditions using disturbed soil samples and under field conditions using intact soil cores were conducted on a chronosequence of 2-, 6-, 9- and 14-year-old DMC fields (DMC-2, DMC-6, DMC-9 and DMC-14, respectively). The average increase of organic C in the 0–30 cm topsoil layer under DMC was 1.91 Mg C ha−1 year−1. Soil total N increased with 103 kg N ha−1 year−1 (0–30 cm). The potential N mineralization rate under laboratory conditions (28°C, 75% of soil moisture at field capacity) was 0.27, 0.28, 0.39 and 0.36 mg N kg soil−1 day−1 for, respectively, the DMC-2, DMC-6, DMC-9 and DMC-14 soils. The corresponding specific N mineralization rates were 0.16, 0.15, 0.22 and 0.17 mg N g N−1 day−1. There was no obvious explanation for the higher specific N mineralization rate of soils under DMC-9, given the similar soil conditions and land-use history before DMC was introduced. Results from the in situ N incubation experiments were in good agreement with those from the laboratory incubations. We estimated that soil N mineralization increases with about 2.0 kg N ha−1 year−1 under DMC. The increase was mainly attributed to the larger soil total N content. These results indicate that even in the medium term (10 years), continuous DMC cropping has limited implications for N fertilization recommendations, since the extra soil N supply represents less than 20% of the common N fertilization dose for maize in the region

A key principle of direct seeding mulch-based cropping systems is the retention of crop residues on the soil surface to preserve soil water for crop growth. In this study the impact of surface crop residue on water use and production risk associated with rainfall variability is analysed for two contrasting tropical sites. The two sites are La Tinaja in semi-arid Mexico and Planaltina in humid Brazil. The crop growth model STICS, version 3.0 was updated with a simple empirical module, incorporating the following effects of surface residue on soil water balance: (1) rainfall interception and subsequent mulch evaporation; (2) radiation interception with associated reduction of soil evaporation and (3) reduction of surface water runoff. The results of the model simulations showed that the effect of radiation interception at both sites was much more important than the effect of intercepting rain. The high sensitivity of model yield predictions to surface water runoff, especially in La Tinaja, highlighted the importance of a careful parameterisation of the surface water runoff formalism. The model results suggested that even small amounts of surface residue are effective at reducing water loss and increasing yield. In La Tinaja, grain yield was increased at least twofold with retention of 1 Mg ha-1 surface residue. In Planaltina, the advantage of water conservation by surface residue is partly offset by increased drainage losses. As a consequence, the impact of crop residue mulching on grain yield was lower at that site.

In the context of conservation agriculture on small scale farms of the Brazilian Cerrado, we hypothesized that planting a cover crop in relay with a commercial crop improves the efficiency of use of available natural resources, increasing biomass for use as fodder without reducing the grain yield of the main crop. The objective of this study was to measure the performance of two intercropped systems in terms of total above-ground biomass production and maize (Zea mays) grain yield: pigeon pea (Cajanus cajan) and Brachiaria (Brachiaria ruziziensis) sown as cover crops in established maize under a no-tillage management. The cover crops were sown at two different dates and a comparison was made with the three crops sown as a sole crop at the early sowing date. The experiment was conducted during the 2007-2008 and 2008-2009 growing seasons. Maize grain yield was not reduced by the presence of the relay cover crops in comparison with maize as the sole crop, even when the cover crop was sown soon after maize emergence. In contrast, the production of above-ground biomass by the cover crop was significantly lower when grown with maize than it was when grown as a sole crop. In the intercropped systems, when sown early, the cover crop produced higher total biomass than when sown late. Total above-ground biomass production of maize intercropped with a cover crop was much higher than that of any of the crops sown alone: the total biomass (average of the two growing seasons) produced by maize and pigeon pea was more than double that of maize grown alone. The land equivalent ratio (LER) of maize grain yield and biomass production was higher than one whatever the intercropped system used. It was particularly high when maize was intercropped with early sown pigeon pea; grain yield LER and biomass LER reaching, respectively, 1.72 and 1.73 in 2007-2008 and 2.02 and 2.03 in 2008-2009. These high LER values provide evidence for the complementary and the high efficiency of use of available resources by the intercropped plants and thus the advantage of such systems to produce both maize grain and cover crop forage under the conditions of our study.

O objetivo deste trabalho foi avaliar o efeito das palhadas de milho, milheto e soja na capacidade de interceptação e de armazenamento de água, velocidade de dessecamento, porcentagem de cobertura do solo, interceptação da radiação solar e escoamento superficial, assim como incorporar estes efeitos em um modelo de crescimento de plantas. As palhadas de milheto e de milho apresentaram capacidade maior de armazenar água do que a de soja: 3,26, 3,24 e 2,62 g de água por grama de palhada, respectivamente. A quantidade de água perdida pelos resíduos foi proporcional à evapotranspiração potencial. As taxas de cobertura foram equivalentes nos três tipos de material. Os três tipos de palhada foram similares na interceptação das radiações fotossinteticamente ativa e infravermelha. Os resíduos do milheto foram eficientes no controle do escoamento superficial: do total de 843,5 mm de água precipitada, apenas 45,5 mm foram perdidos pelo escoamento superficial no sistema de plantio direto enquanto no convencional as perdas de água foram de 222,5 mm. Os modelos linear e exponencial expressam de forma significativa a maior parte das relações estudadas. The objective of this work was to evaluate the effects of crop residue mulches from maize, millet and soybean on water storage capacity, water evaporation, soil cover, solar radiation interception and surface water run-off as well as to incorporate these effects in a crop growth model. The mulch of millet and maize presented higher capacity for water storage than soybean mulch: 3.26, 3.24 and 2.62 g of water per gram of dry matter, respectively. Water losses from wet mulches were related to the potential evapotranspiration. The soil cover levels were similar among the three types of material. The three types of mulch intercepted similar quantities of photosynthetically active radiation and infrared radiation. The mulch of maize straw was slightly more efficient in intercepting radiation than that from millet or soybean. Mulching with millet residues was efficient in the control of surface water run-off: only 45.5 mm of water (out of 843.5 mm rainfall) was lost through runoff under the no-till system with millet as cover crop, whereas 222.5 mm of water was lost in the conventional system with tillage. Most of the relations derived in this work could be described by exponential models.

An accurate estimation of crop yield under climate change scenarios is essential to quantify our ability to feed a growing population and develop agronomic adaptations to meet future food demand. A coordinated evaluation of yield simulations from process-based eco-physiological models for climate change impact assessment is still missing for soybean, the most widely grown grain legume and the main source of protein in our food chain. In this first soybean multi-model study, we used ten prominent models capable of simulating soybean yield under varying temperature and atmospheric CO2 concentration [CO2] to quantify the uncertainty in soybean yield simulations in response to these factors. Models were first parametrized with high quality measured data from five contrasting environments. We found considerable variability among models in simulated yield responses to increasing temperature and [CO2]. For example, under a + 3 °C temperature rise in our coolest location in Argentina, some models simulated that yield would reduce as much as 24%, while others simulated yield increases up to 29%. In our warmest location in Brazil, the models simulated a yield reduction ranging from a 38% decrease under + 3 °C temperature rise to no effect on yield. Similarly, when increasing [CO2] from 360 to 540 ppm, the models simulated a yield increase that ranged from 6% to 31%. Model calibration did not reduce variability across models but had an unexpected effect on modifying yield responses to temperature for some of the models. The high uncertainty in model responses indicates the limited applicability of individual models for climate change food projections. However, the ensemble mean of simulations across models was an effective tool to reduce the high uncertainty in soybean yield simulations associated with individual models and their parametrization. Ensemble, ensemble mean yield responses to temperature and [CO2] were similar to those reported from the literature. Our study is the first demonstration of the benefits achieved from using an ensemble of grain legume models for climate change food projections, and highlights that further soybean model development with experiments under elevated [CO2] and temperature is needed to reduce the uncertainty from the individual models. Made available in DSpace on 2022-02-25T18:00:30Z (GMT). No. of bitstreams: 1 AP-Soybean-models-2022.pdf: 10546770 bytes, checksum: 6995390284b79cf3d71d808e0570f1cc (MD5) Previous issue date: 2022

Simple Summary The husbandry of high-producing dairy cattle on pasture in tropical regions promotes heat stress and alters physiological and behavioral parameters. However, it is unknown how the physiological and behavioral responses of cows more adapted to tropical environments under heat stress conditions, with lower milk production under shaded pasture or full sun conditions. To respond to these questions, Gyr dairy and Girolando cows (5/8 Holstein 3/8 Gyr, and ½ Holstein ½ Gyr) were evaluated in full sun and under natural shade from trees. Behavioral, physiological, and morphological variables were measured, and it was concluded that shaded pasture for dairy zebu cows promotes animal welfare by mitigating animal surface temperature and increasing rumination time. Abstract Under conditions of high temperature, humidity, and incidence of solar radiation, dairy cows use behavioral changes as a strategy to decrease the metabolic heat production at pasture. The objective of this study was to evaluate the behavioral and physiological responses of Gyr and Girolando (5/8 Holstein 3/8 Gyr, and ½ Holstein ½ Gyr) dairy cows submitted to environments with and without shade. The experiment was conducted at Embrapa Cerrados (Technology Center for Dairy Zebu breeds—CTZL), Brasilia, Distrito Federal—Brazil, with 48 Gyr and Girolando cows total in the lactation group, with low to medium milk production, in full sun or shade with Eucalyptus urograndis (267 plants/ha−1). The physiological and behavioral characteristics evaluated were panting score, superficial temperature, and time spent grazing, ruminating, and lying down. Other traits included skin and coat thickness, hair diameter, density and length, and predominant coat color. In addition, body measurements, such as body length, the height of withers, chest circumference, and shin circumference, were measured. Shaded cows had 34% longer rumination times than cows in full sun (p = 0.01). With a temperature-humidity index ranging from 79 to 83, the rumination time was 1.7 times higher in cows under shade (p = 0.01) during a 24-h period of observation. There were no significant differences in the grazing time between the environments, but lying time was 23% longer in cows under the sun (p = 0.01). The panting score was not influenced by the environment (p = 0.17). Girolando cows had a 35% higher panting score than Gyr cows (p = 0.01) regardless of the environment. The panting score increased two and a half times during the afternoon compared with the morning (p = 0.01). The surface and rectal core temperatures had significant differences between treatments and time of the day. Body measurements were not different between cows in both environments, but there was a difference between breeds. The use of trees in pastures with a silvopastoral system for dairy zebu cows is indicated to improve grazing behavior, as well as time spent ruminating and lying down.

Resumo Apesar da mandioca ser reconhecida pela sua elevada tolerância à seca, a irrigação vem apresentando resultados satisfatórios. Entretanto, poucos estudos vêm sendo desenvolvidos visando a determinação dos efeitos da cobertura do solo, da irrigação e da combinação de ambos no desenvolvimento da cultura. O objetivo deste estudo foi determinar a influência da irrigação e da cobertura plástica do solo, no desempenho agronômico de mandioca de mesa. O plantio foi feito em canteiros, no sistema de fileira dupla com as manivas-sementes implantadas na vertical em espaçamento de 0,60 m entre linhas e 0,80 m entre plantas. Foram aplicados os tratamentos canteiro desnudo sem irrigação, canteiro coberto com plástico de polietileno preto sem irrigação, canteiro desnudo com irrigação e canteiro coberto com plástico de polietileno preto com irrigação. As irrigações foram por aspersão convencional, com base no balanço diário de água do solo na profundidade efetiva do sistema radicular da mandioca nos diferentes estágios de desenvolvimento da cultura. Os caracteres avaliados em duas safras foram: produtividade de parte aérea, produtividade de raízes, porcentagem de amido nas raízes e tempo para a cocção. A expressão dos caracteres produtividade de raízes, peso da parte aérea e teor de amido nas raízes, foi influenciada pelo manejo da irrigação e pela cobertura do solo. A utilização individual das tecnologias de irrigação e de cobertura plástica do solo, proporcionaram aumentos de produtividade de raízes de 55% e 13%, respectivamente, e quando foram utilizadas em conjunto a produtividade de raízes aumentou 89%. Made available in DSpace on 2021-04-08T15:34:55Z (GMT). No. of bitstreams: 1 Antonini-Desempenho-agronomico-de-cultivares.pdf: 717538 bytes, checksum: 4278ae94e20425dbff10c70671c8dcd5 (MD5) Previous issue date: 2020

Conservation agriculture (CA) is recognized as a promising crop management strategy for sustainable agricultural intensification. The objective of this study was to evaluate CA cropping systems for rainfed maize as an alternative to the traditional tillage-based cropping systems (CT) in the context of family farms, using a multi-criteria model that represents the point of view of farmers. Farmers considered several aspects for evaluating the cropping systems, thatwere systematized in the model through five criteria (with sub-criteria): (a) costs; (b) yield; (c) labour; (d) human health and environment; and (e) production risks. CA did not differ from CT for the ?costs? criterion but was superior for the ?yield? and ?labour? criteria. In contrast, CT obtained better ratings for the criteria ?human health and environment? and ?production risks?. Considering all criteria, CA was better appraised than CT. However, a new local policy measure that subsidizes the hiring of mechanized tillage services overturns this outcome, indicating the importance of exogenous factors. Overall, the participatory processes in building the model allowed us to better understand the reasons of adoption or non-adoption of CA by small-scale farmers in the tropics. Made available in DSpace on 2020-09-23T08:17:09Z (GMT). No. of bitstreams: 1 Jose-Humberto-Participatory-multicriteria-assessment-of-maize-cropping-systems.pdf: 3072333 bytes, checksum: 97c9c81f58b5755abd945d93b166a071 (MD5) Previous issue date: 2020

Cet article retrace les principales étapes d’une recherche franco-brésilienne portant sur la caractérisation des risques de stress hydrique dans les Cerrados brésiliens, avec l’objectif de faire des recommandations pour les réduire, à la fois en termes de pratiques culturales et en termes de politique d’assurance agricole. Un zonage agroclimatique à l’échelle régionale a permis d’améliorer le système de crédit de campagne et d’assurance agricole dont bénéficient les grandes exploitations agro-industrielles de la région. Le cas des exploitations familiales a été ensuite étudié en ayant recours à la modélisation des systèmes de culture et des exploitations. L’emploi de ces modèles a montré que les risques auxquels les exploitants sont confrontés sont très variables selon les milieux et peuvent limiter les possibilités d’intensification. Ces modèles pourraient être utilisés pour améliorer le système d’assurance existant et en particulier pour mieux tenir compte des contraintes propres aux divers types d’exploitations familiales., This paper recalls the principal stages of a French-Brazilian research program on the management of farmers’ production risks due to water stress in the Brazilian Cerrados. The objective was to make recommendations to lower the production risks, in terms of both agricultural management practices and insurance policies. An agro-climatic classification at a regional scale allowed for the creation of more efficient credit systems and agricultural insurance coverage, which were mostly beneficial to the large agro-industrial farmers of the region. Subsequently, the case of the smallholder farms was studied by using cropping systems and farm models. The application of these models showed that the risks with which small-scale farmers are confronted are very variable according to the environmental conditions and that they are a limiting factor for a possible intensification of the production. These models, which take into account the constraints specific to the various types of small-scale farms, might be used as a tool for improving existing agricultural insurance systems, particularly in order to better integrate the constraints specific to small-scale farms

Nas regiões tropicais, principalmente no cerrado brasileiro, para assegurar uma produção agrícola sustentável, é preciso recorrer a novos sistemas de cultura. Por isso, foi desenvolvido o Sistema de Plantio Direto com Cobertura vegetal, que preconiza o não-revolvimento do solo e o cultivo de plantas de cobertura, antes ou depois da cultura comercial, para produzir mais biomassa e proteger permanentemente o solo. Made available in DSpace on 2011-04-09T14:34:15Z (GMT). No. of bitstreams: 1 v22n1p169.pdf: 101798 bytes, checksum: 98c60aec7c709b618f10b4b4ba2ee0fe (MD5) Previous issue date: 2005-12-06

Under the humid tropical climate of the Brazilian cerrados, new cropping systems have become necessary to ensure sustainable agricultural production. Direct-sowing mulch-based cropping systems (DMC) introduce a cover crop before or just after the commercial crop. They help farmers enhance natural resources and produce more total biomass during the year. Crop residues protect the soil and increase organic restitution to the system. In 1999, a Franco-Brazilian collaborative project began scientific studies aimed at quantifying the impact of DMC, especially on the dynamics of water, carbon and nitrogen. DMC systems significantly decrease water runoff. In this way they effectively fight against soil erosion, even if additional infiltrated water can sometimes saturate the system and escape by drainage. The cover crop can then recycle some of that drainage loss and protect and use water resources better throughout the year. DMC systems also provide more favourable conditions that ensure the more intensive and more regular mineralisation of soil organic matter during the rainy season. Some of the organic mulch mineralises at the same time, providing the commercial crop with the benefit of a higher pool of inorganic nitrogen. The additional cover crop can recycle part of the nitrogen not used by the commercial crop and some of the nitrogen mineralised before or after this commercial cycle. Under DMC high microbial activity is responsible for higher CO2 emissions to the atmosphere, but the soil carbon balance is nonetheless positive because of the large biomass production and organic input from the introduction of the cover crop. Even under the hot and humid conditions of the cerrados, soil carbon content increases under the more productive DMC systems. Made available in DSpace on 2020-01-20T18:03:46Z (GMT). No. of bitstreams: 1 CNPAF2005ce.pdf: 100999 bytes, checksum: cbf49f449bd9181181fdc4f26010e424 (MD5) Previous issue date: 2005