Centro Operativo e de Tecnologia de Regadio

The evaluation of the spatial and temporal variability of soil properties can be valuable to improve crop productivity and soil health. A study of soil properties was carried out in southern Portugal, in three farm fields with irrigated annual crops (layers 0–20 cm and 20–40 cm), over three years. Factor Analysis (FA) and Discriminant Analysis (DA) were used to analyze the data. With FA, the observed variables were grouped into a smaller number of latent variables related to soil attributes. Discriminant Analysis was used to classify and identify the most dominant attributes and indicators for the time and space variability of soil parameters. The FA performed for the surface layer included factors related to texture, water and nutrient retention capacity, chemical composition, and soil fertility. In the sub-surface layer, the factor structure was similar, with four factors related to texture, chemical composition, nutrient availability, and soil fertility. The most influential factors and variables in temporal discrimination (sampling dates) in both layers were those related to chemical composition, with electric conductivity as the preponderant indicator. As for the spatial differentiation (fields), the dominant factor in the surface layer was texture, and in the sub-surface layer, nutrient availability. The most important discriminant indicators of spatial variability were fine sand proportion and available potassium, respectively, for the surface and sub-surface layers. The results obtained showed potential for the multidimensional and integrated assessment of patterns of temporal and spatial variation of soil functions from agricultural practices or soil degradation processes.

Umbrella pine (Pinus pinea L.) cones take three years to develop. With the increasing frequency of extreme droughts, water available for trees has decreased—climate change is a reality. The cone’s survival in its first two years of development and the average cone weight during its last year of maturation is affected, thus, reducing kernel quantity and quality. Climate change has resulted in forest fires becoming an inescapable issue in forest management planning. A literature review was carried out, focusing, on one hand, the predicted climatic changes for the Mediterranean basin and, on the other hand, the umbrella pine silvicultural mechanisms at tree, stand, and landscape levels that may help to face these constraints. Finally, the Portuguese case was focused, describing the management practices that are being adopted to achieve, even when the period of cone formation and growth include dry years, one to six tons of cones per hectare per year in adult stands.

To evaluate water-nitrogen interactions on irrigated wheat production, it is important to know: the dose, the fractioning, and the most recommended period of fertilizers application; the best irrigation volumes and schedules for meeting the crop requirements, ensuring the minimum leaching risks, to obtain the highest yields and quality of the grain, while achieving high water and nitrogen use efficiencies. This study evaluated the interactive effect of irrigation and nitrogen fertilization, with conventional and enhanced efficiency fertilizers, on yield, irrigation water use efficiency and grain quality of soft wheat. For this purpose, two trials were carried out during the 2016/2017 in Beja, Alentejo, under two irrigation strategies: D1 (100% of crop evapotranspiration – ETc - throughout the cycle) and D2 (100% of ETc only at four stages: beginning of stem extension; booting; heading; grain filling). In one trial, enhanced efficiency N fertilizers were applied through 6 splitting treatments. In the other, conventional N fertilizer was applied through 5 splitting treatments. The results suggest that, on one hand, early applications of advanced efficiency fertilizers do not compromise the crop yield and, on the other hand, the availability of nitrogen in the booting stage is important to obtain higher grain protein content.

Nos ambientes mediterrânicos, a gestao da agua de rega e a estrategia de fertilizacao azotada sao determinantes nas respostas produtivas e de qualidade tecnologica do trigo para panificacao. Neste estudo foram avaliados os efeitos da rega e da fertilizacao azotada sobre a produtividade do trigo mole na regiao do Alentejo, Sul de Portugal, em 2018. Testaram-se 3 tratamentos de rega e 8 tratamentos de tipo/fracionamento do fertilizante azotado. Os tratamentos de rega foram: R1 (rega com reposicao de 100% da evapotranspiracao cultural (ETc); R2 (rega com reposicao de 100% da ETc apenas em quatro fases: inicio do encanamento, emborrachamento, ântese, enchimento do grao); R3 (sequeiro). Os tratamentos de fertilizacao azotada incluiram 4 tipos de adubos (classico; de libertacao controlada; com inibidor de nitrificacao; com inibidor da urease) aplicados totalmente a sementeira ou fracionados ao longo do ciclo. O ano hidrologico de 2017/2018 decorreu de forma anomala no que respeita a distribuicao e volume de precipitacao: a precipitacao acumulada durante o ciclo de desenvolvimento cifrou-se em 479 mm; entre 26 de Fevereiro e 19 de Marco, e entre 18 e 24 de Maio, registaram-se volumes de precipitacao de 222.3 mm e 82.5 mm, respectivamente. Nas modalidades R1 e R2 apenas se verificaram dois pequenos periodos de stress hidrico na fase inicial da cultura. Na modalidade R3, verificaram-se periodos mais prolongados de stress hidrico e em maior numero, que coincidiram com o final da fase de afilhamento e na fase de enchimento do grao. No que respeita a avaliacao agronomica, nao se verificaram efeitos significativos dos factores em estudo em qualquer dos parâmetros analisados, nomeadamente na producao de grao e seus componentes. Este conjunto de resultados reflecte o comportamento bastante semelhante do balanco de agua no solo nas tres modalidades de rega em estudo, como consequencia da forma anormal como decorreu o ano hidrologico em causa.