Neste trabalho, o método de volumes finitos foi utilizado com esquema de discretização mais elaborado, chamado Flux-Spline, a fim de simular numericamente problemas unidimensionais não lineares de infiltração de água em solo hidraulicamente homogêneo não-saturado. Problemas-teste foram apresentados e resolvidos para alguns valores e combinações dos dois parâmetros adimensionais de governo, para demonstrar as vantagens do novo esquema quando comparado ao tradicional esquema de diferença central. Os resultados obtidos mostraram melhor desempenho do esquema quando comparado à diferença central, em todos os casos simulados, demonstrando que o esquema pode ser recomendado para a simulação numérica de movimentação de água em solo hidraulicamente homogêneo não-saturado.<br>In this work the finite volume method was used with an improved scheme of discretization called Flux-Spline, for the numerical study of non-linear problems in uni-dimensional water flow in hydraulically homogeneous unsaturated soil. Test-problems were presented and resolved to some values and combinations of the two governing non-dimensional parameters to demonstrate the advantages of the new scheme when compared to the traditional central difference scheme. The results obtained showed a better performance of the new scheme when compared to the central difference scheme in all simulated cases, demonstrating that the scheme can be recommended for numerical simulation of water movement in hydraulically homogeneous unsatured soil.

The main goal of the article was to discuss the importance of introducing short supply chains in the context of minimizing the adverse effects of traditional supply chains. The paper presents a case study of the Local Product of Malopolska as an example of good practice. When analyzing the concept of shortened supply chains, some significant benefits for agricultural producers, consumers and the region can be noticed. Reduction of the food chain links brings more benefits to farmers, and can contribute to avoiding the Forrester`s effect repercussions. Short food chains can be used to promote a region, as well as organic, local or traditional products. Despite the weaknesses of the local dimension of this concept, the idea contributes to sustainable development, which links economic goals, with social and environmental objectives. Presented reflections do not exhaust the subject, but only signal a topic that requires a holistic approach to the subject. / Synopsis. Celem artykułu była analiza i ocena znaczenia krótkich łańcuchów dostaw w kontekście minimalizowania niekorzystnych zjawisk występujących w klasycznych łańcuchach dostaw. W pracy przedstawiono studium przypadku Produkt Lokalny z Małopolski, jako przykład dobrych praktyk. Analizując koncepcję skróconych łańcuchów dostaw można zauważyć istotne korzyści dla producentów rolnych, dla konsumentów, a także dla regionu. Ograniczenie ogniw łańcucha żywnościowego przynosi więcej korzyści rolnikowi, a dzięki skróceniu łańcucha do minimum można uniknąć reperkusji efektu Forrestera. Krótkie łańcuchy żywnościowe można zastosować do promocji regionu, produkcji ekologicznej, czy też produktów lokalnych i tradycyjnych. Mimo słabych stron jakim jest lokalny wymiar omawianej koncepcji, idea ta przyczynia się do realizacji założeń rozwoju zrównoważonego, która łączy cele ekonomiczne, z celami społecznymi i ochroną środowiska. Przedstawione rozważania nie wyczerpują tematu, a jedynie sygnalizują zagadnienie, które wymaga całościowego podejścia do tej tematyki.

Celem artykułu była analiza i ocena znaczenia krótkich łańcuchów dostaw w kontekście minimalizowania niekorzystnych zjawisk występujących w klasycznych łańcuchach dostaw. W pracy przedstawiono studium przypadku Produkt Lokalny z Małopolski, jako przykład dobrych praktyk. Analizując koncepcję skróconych łańcuchów dostaw można zauważyć istotne korzyści dla producentów rolnych, dla konsumentów, a także dla regionu. Ograniczenie ogniw łańcucha żywnościowego przynosi więcej korzyści rolnikowi, a dzięki skróceniu łańcucha do minimum można uniknąć reperkusji efektu Forrestera. Krótkie łańcuchy żywnościowe można zastosować do promocji regionu, produkcji ekologicznej, czy też produktów lokalnych i tradycyjnych. Mimo słabych stron jakim jest lokalny wymiar omawianej koncepcji, idea ta przyczynia się do realizacji założeń rozwoju zrównoważonego, która łączy cele ekonomiczne, z celami społecznymi i ochroną środowiska. Przedstawione rozważania nie wyczerpują tematu, a jedynie sygnalizują zagadnienie, które wymaga całościowego podejścia do tej tematyki. | The main goal of the article was to discuss the importance of introducing short supply chains in the context of minimizing the adverse effects of traditional supply chains. The paper presents a case study of the Local Product of Malopolska as an example of good practice. When analyzing the concept of shortened supply chains, some significant benefits for agricultural producers, consumers and the region can be noticed. Reduction of the food chain links brings more benefits to farmers, and can contribute to avoiding the Forrester`s effect repercussions. Short food chains can be used to promote a region, as well as organic, local or traditional products. Despite the weaknesses of the local dimension of this concept, the idea contributes to sustainable development, which links economic goals, with social and environmental objectives. Presented reflections do not exhaust the subject, but only signal a topic that requires a holistic approach to the subject. | łańcuch żywnościowy, zarządzanie, zagrożenia, korzyści, produkt lokalny | food chain, management, constraints, benefits, local product | 13 | 155-165 | 2

O milheto (Pennisetum glaucum) é cultivado em épocas com deficiência hídrica, o que pode afetar a absorção de K. Este trabalho visou quantificar a importância de potenciais de água do solo (-0,03; -0,05; -0,10 e -0,50 MPa), associados a doses de potássio (15 e 120 mg dm-3 de K) na morfologia radicular e nos processos de transporte de K às raízes de milheto. O experimento foi realizado em Botucatu (SP), em casa de vegetação. O milheto foi cultivado até 28 dias após a emergência, quando foram avaliados a fitomassa produzida e os teores de K, assim como a morfologia radicular. Foi estimada a contribuição do fluxo de massa e da difusão para o transporte de K no solo. Independentemente da dose de potássio e do teor de água no solo, a difusão foi o principal mecanismo de transporte de K até as raízes do milheto. Houve maior contribuição relativa do fluxo de massa, que correspondeu a 12 % do absorvido, na menor dose de potássio, contra 4 % na maior dose. Não houve efeito da disponibilidade hídrica nos mecanismos de transporte de K até as raízes do milheto. | Pearl millet is usually grown in periods when water is deficient in soil; a fact that possibly affects the K uptake. The experiment in Botucatu, São Paulo State, Brazil, was conducted to evaluate the effects of soil water content (-0.03;-0.05;-0.10 and -0.50 MPa) associated with K rates (15 and 120 mg dm-3 of K) on the K mass flow and diffusion to pearl millet (Pennisetum glaucum (L.) Leek) roots in greenhouse conditions. In pots with soil from the arable layer of a Red Latosol, pearl millet was grown for 28 days after plant emergence, when the plants were harvested and the shoot and root dry matter, K contents, as well as the root morphology determined. K mass flow and diffusion to roots were estimated. Irrespective of soil K level and water content, diffusion was the main mechanism of K supply to the roots. There was a larger relative contribution of mass flow at the K lowest rate, which amounts to 12% of the total K uptake, compared to 4% at the highest K rate. No effect of the soil water content on the mechanisms of K supply to pearl millet roots was established.

O milheto (Pennisetum glaucum) é cultivado em épocas com deficiência hídrica, o que pode afetar a absorção de K. Este trabalho visou quantificar a importância de potenciais de água do solo (-0,03; -0,05; -0,10 e -0,50 MPa), associados a doses de potássio (15 e 120 mg dm-3 de K) na morfologia radicular e nos processos de transporte de K às raízes de milheto. O experimento foi realizado em Botucatu (SP), em casa de vegetação. O milheto foi cultivado até 28 dias após a emergência, quando foram avaliados a fitomassa produzida e os teores de K, assim como a morfologia radicular. Foi estimada a contribuição do fluxo de massa e da difusão para o transporte de K no solo. Independentemente da dose de potássio e do teor de água no solo, a difusão foi o principal mecanismo de transporte de K até as raízes do milheto. Houve maior contribuição relativa do fluxo de massa, que correspondeu a 12 % do absorvido, na menor dose de potássio, contra 4 % na maior dose. Não houve efeito da disponibilidade hídrica nos mecanismos de transporte de K até as raízes do milheto.