Avaliação de um circuito eletrônico para medição da condutividade elétrica de soluções nutritivas.

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Comparação dos dados de temperatura do ar obtidos em estação meteorológica convencional e automática na região do Submédio São Francisco.

A Biblioteca possui os resumos em papel

Métodos de estimativa da evapotranspiração de referência para a região de Sete Lagoas, MG.

CONBEA 2012

Mitigating the effects of future climate on maize productivity.

Current climate changes affect agricultural production. Crop management strategies can be used to mitigate these effects. This study was carried out to evaluate the use of crop and soil management strategies to mitigate the effects of future climate on maize yield in mesoregions of the state of Minas Gerais, Brazil. The CSM-CERESMaize model was used to simulate the effect of maize root system depth and of the amount of plant residue left on the soil surface by the previous crop in maize yield for different scenarios of change in precipitation and solar radiation. The decrease in rainfall volume reduced the average maize yield in some regions by more than 50%. The increase in solar radiation maize yield rise, while its reduction caused more than 20% yield drop in most regions. The management strategies evaluated have the potential to mitigate such effects

Modelling management strategies to mitigate the effects of alterations of temperature and of CO2 concentration on maize.

Ongoing climate change may affect rainfed maize yield in Brazil, which can be attenuated by some crop management strategies. This work aimed to evaluate, by using computational modeling, management practices with potential to mitigate the effects of changes in temperature and CO2 concentration on maize yield. The CSM-CERES-Maize model was applied to simulate the mitigating potential of using maize cultivars with 0.3 m, 0.5 m and 0.7 m deep root system, associated with 0 t ha-1, 2 t ha-1 and 4 t ha-1 of crop residue left on the soil surface. A set of 33 years of daily weather data, along with soil profile data, were used to evaluate the approach in 10 regions of the state of Minas Gerais, Brazil. For most of the regions, the use of mulching and of a maize cultivar with deeper root system was not capable of attenuating the temperature rise. In contrast, any factor limiting root growth of maize to a depth of 0.30 m, causes significant yield drop, even for a scenario of reducing temperature by 3 oC or rising CO2 concentration. In warmer and drier regions, the positive response of maize to the increase in CO2 concentration was more pronounced

Uma metodologia alternativa para o zoneamento de risco climático da cultura do milho.

Produzir milho sob condições de sequeiro é uma prática comum no Brasil. Neste sistema, de produção as culturas são fortemente afetadas pela inerente variabilidade climática anual e interanual, especialmente pelos veranicos, que afetam a produtividade. Uma das estratégias mais simples, com praticamente nenhum custo, para mitigar este problema é a determinação de uma janela de semeadura, que minimize os efeitos negativos da variabilidade climática na agricultura de sequeiro. Os objetivos deste estudo foram: a) usar os resultados de produtividade de milho simulada com um modelo baseado em processos, para estabelecer janelas de semeadura e b) comparar os resultados obtidos com a atual metodologia empregada pelo Ministério da Agricultura, Pecuária e Abastecimento (Mapa). Utilizou-se o modelo CSMCERES-Maize, do Sistema de Apoio à Decisão para Transferência de Agrotecnologia (DSSAT), para simular cenários de épocas de semeadura semanais, sob condições de sequeiro, para municípios do Estado de Minas Gerais. Para cada época de semeadura, determinou-se a quebra de rendimento, comparando o rendimento médio da época de semeadura atual com o maior rendimento médio obtido a partir de todas as datas de semeadura. Assim, cada data de semeadura foi associada a um risco de perda de rendimento. As janelas de semeadura obtidas a partir das simulações foram ligeiramente diferentes daquelas propostas pelo Mapa. O uso de modelos baseados em processos para simular o rendimento das culturas permite a integração de muitos fatores não considerados na atual metodologia de zoneamento agrícola utilizada pelo Mapa. A abordagem proposta tem vantagens sobre a metodologia do Ministério da Agricultura, entre as quais a possibilidade de determinar o rendimento médio esperado e a sua amplitude.bitstream/item/94391/1/bol-87.pd

Use of lower quality water in irrigated agriculture and effects on forages with productive potential in Semiarid regions: a review.

In the agricultural sector, using lower quality water sources has increased in irrigation practice. Thus, this review summarizes the consequences of using brackish and/or saline water in irrigated agriculture, highlighting some effects on soil and plants in general. Water quality for irrigation and the salinity tolerance threshold of forage species with productive potential for semiarid regions are also discussed. Between January and June 2022, a systematic search was carried out for studies that evaluated the quality of water for irrigation, the effects of using water with excess salts on the soil and on plants in general, and on forage species with productive potential in semiarid regions. The databases consulted were: ScienceDirect, Scopus, Wiley Online Library, Web of Science, Taylor and Francis, and Scholar Google. A total of 1567 studies were found. Of these, 200 studies were reviewed and 154 were used because they met the review objective. The forage plants reported here have salinity tolerance ranging from low to moderate. The management adopted, as well as the species used, are factors that influence the performance of the crop under stress. Although they are widely cultivated in arid and semiarid regions of the world, few studies still show the salinity threshold of these crops, mainly for forage cactus, sunflower, and pigeon pea species. Therefore, it is essential to carry out more research on this topic in order to provide information that improves the management of production systems in saline environments around the world.Online

Soil properties and microclimate of two predominant landscapes in the Brazilian semiarid region: comparison between a seasonally dry tropical forest and a deforested area.

The Brazilian semiarid region has been subjected to strong man-made actions since the 1970s, which have resulted in landscape transformation. The scientific literature presents several studies on the soil properties or microclimate of different types of landscapes; however, less attention was having been paid to the surface contrast between native vegetation and bare soil. The objective of this research was to evaluate the soil properties and microclimate of two common landscapes in the Brazilian semiarid region, a seasonally dry tropical forest (Caatinga) and a deforested area. Soil and microclimate data were obtained from two sites, both located in the State of Pernambuco, Brazil. Soil samples were collected on six dates and from layers, and microclimate variables were measured for three years. Soil properties and microclimatic data were evaluated using the MannWhitney test, as well as regression and principal component analysis. Successive years of agricultural practices affected the bulk density, promoting an increase in the total porosity of the soil in the deforested area site. In addition, changes were verified in the magnitude of many chemical properties (pH, P, K+, Mg2+, Cu2+, Fe, Mn, Zn2+ and Ca2+), indicating soil degradation. Compared with the Caatinga forest site, the minimum air temperature was 2.3 ◦C, and the maximum vapor pressure deficit was 7% higher in the deforested area site, and it is very likely that Caatinga removal there will lead to a reduction in precipitation. The results suggest that Caatinga vegetation removal followed by agricultural practices and subsequent land abandonment promotes significant changes in soil properties and the microclimate, which can contribute to advances in desertification and affects agricultural activities in the Brazilian semiarid region

Integrated management of agronomic practices in the forage cactus: maximizing productivity, biological efficiency and economic profitability.

Forage cactus cropping systems that include a combination of agricultural practices (cloning, irrigation, mulching, and/or intercropping) can increase forage production and economic return in semi-arid environments. This study evaluated the effect on productivity, biological efficiency, and economic return of combining different practices with forage cactus cropping systems in the semi-arid region of Brazil. The research was conducted in four experimental areas, in a randomized block design with four replications, and included the following practices: 1) clones – irrigation - cover, 2) different irrigation depths, 3) intercropping - mulching, and 4) different levels of mulch. The treatments in experiment I consisted of three cactus clones (‘Orelha de Elefante Mexicana’—OEM; ‘Miúda’—MIU and ‘IPA-Sertânia’—IPA), two water regimes (rainfed and irrigated), and two levels of mulch (with and without mulch). Experiment II comprised four irrigation depths (0, 40, 80, and 120% of the crop evapotranspiration) and three cactus clones. In experiment III, three crop arrangements (single cactus, cactus intercropped with millet, and single millet) were evaluated under two levels of mulching (with and without mulching). In experiment IV, four levels of mulch were used (0, 5, 10, and 15 Mg ha-1). The total number of cladodes per plant, fresh matter yield (YFM), dry matter yield (YDM), and final plant density were obtained when harvesting. Economic viability was assessed using the profitability index (PI). The rainfed systems showed greater yield. The use of mulch afforded greater productivity. The OEM clone (YFM = 310.76 Mg ha-1 and YDM = 29.87 Mg ha-1) obtained a higher yield than did the IPA and MIU clones. The highest PI values were achieved under the rainfed systems. The MIU and IPA clones exhibited lower PI values. The cactus-millet intercrop achieved the best performance with the use of mulch. Cactus systems of 15.0 Mg ha-1 showed a greater PI value. It was concluded that the integrated management of such practices as intercropping, mulching, and the adoption of the OEM clone can increase the supply of forage. These practices can promote the sustainable intensification of forage input in Livestock Production Systems in semi-arid environments