Traits fonctionnels de Brachiaria (Trin.) Brizantha (Hochst.) Stapf, B. decumbens Stapf et B. ruziziensis (Germ. & Evrard) ndab cultives en association avec Pennisetum glaucum (L.) Leeke R. Br. en climat tropical sec.

L’étude visait à connaître les performances de trois espèces de Brachiaria au Sénégal, en association avec le mil (Pennisetum glaucum (L.) R. Br.), pour protéger le sol. On a comparé, pendant deux ans, trois traitements associant mil et Brachiaria brizantha, B. ruziziensis et B. decumbens avec un témoin mil seul. Les mesures ont porté sur les biomasses aériennes du mil et des Brachiaria et sur les racines des Brachiaria. En 2015, B. ruziziensis a eu la meilleure production (environ 4 tha-1) et B. brizantha la plus faible. Le Brachiaria n’a pas eu d’effet sur le rendement du mil. Pendant la saison sèche 2015-2016, le taux de survie a été nul pour B. ruziziensis et faible pour B. brizantha et B. decumbens. En 2016, les biomasses aériennes des Brachiaria ont été plus élevées. B. brizantha et B. decumbens ont provoqué une baisse de rendement du mil, de 38 et 21 % respectivement. Le profil racinaire de B. ruziziensis est resté proche de celui de 2015, tandis que ceux des autres espèces ont été nettement supérieurs. B. ruziziensis, incapable de survivre à la saison sèche, n’est pas adapté à un usage local comme plante de service. B. decumbens et surtout B. brizantha ont été plus performants, mais concurrencent le mil.Mots-clés : Brachiaira, Sénégal, plante de couverture, association culturale, système racinaire

Avaliação de fontes e doses de fósforo no crescimento inicial do milho.

RESUMO: O fósforo é componente vital para todos os seres vivos e é essencial para a produção agrícola. No Brasil, a maior parte dos solos agricultáveis tem baixos teores de fósforo disponível. Para atender as exigências das plantas e suprimento adequado de fósforo há a necessidade da aplicação de adubos fosfatados. Dentre as opções de fontes no mercado, os fosfatos totalmente acidulados são os usualmente comercializados. Com o aumento do uso dos fosfatos naturais reativos, a avaliação da eficiência da aplicação do fertilizante é importante no manejo da adubação fosfatada. O experimento foi realizado em casa de vegetação, utilizando um Nitossolo. O delineamento experimental empregado foi o inteiramente casualizado com os tratamentos arranjados em um fatorial 4 x 2 com quatro repetições. O objetivo do trabalho foi avaliar os efeitos de fontes e doses de fósforo no crescimento inicial do milho. A produção de matéria seca e os teores de P da parte aérea das plantas de milho aumentaram com o incremento das doses de fósforo, dependentemente da fonte de P considerada. Contudo, o Superfosfato Triplo foi mais eficiente que o fosfato de Arad, garantindo melhor nutrição e crescimento inicial das plantas de milho. ABSTRACT: Phosphorus is an essential element for all living organisms and important also for agricultural production. The content of P in most agricultural soils in Brazil is low. In order to supply the plant needs and the soil fixation, application of P fertilizer is required. Among the various options of P fertilizers in the market, the totally acidified phosphates are usually commercialized. The evaluation of the efficiency of the reactive natural phosphates as P fertilizers is important due to the increase of the utilization of cheaper sources of natural P. The experiment was carried out in green house, using a Nitossolo. The experimental design used was complete randomized design, with the treatments in a 4x2 factorial arrangement, and four replications. The objective of the experiment was to evaluate the effects of sources and rates of P on the growth of corn. The production of dry matter and the content of P on the corn leave and stalks (above ground corn parts) increased as rates of P increased, regardless the P sources tested. However, the Triple Super Phosphate was more efficient compared with Arad phosphate, providing better nutrition and initial growth of corn plants

Using the available indicators of potential biodiversity damage for Life Cycle Assessment on soybean crop according to Brazilian ecoregions

The purpose of the study was to evaluate the use of and suggest possible adjustments to indicators of biodiversity loss for LCA proposed by Chaudhary and Books (2018). For this, we analyzed soybean production in Brazil. Potential damage to biodiversity has been determined for all Brazilian ecoregions: the Amazon; the Atlantic forest; Caatinga; Cerrado; Pampas; and the Pantanal. Two dimensions of assessment were considered – global and regional – in addition to Average-country. An adjustment was proposed for the vulnerability coefficient to the indicators Average-country Brazil: the Regional Species Fragility Index (FI). Two inventories were created using two different functional units: area of production of soybean by ecoregion (year m2); and area corresponding to production of 1 kg of soybean (year m2). Thus, we observed that when the indicators of aggregate values were adopted, the Atlantic Forest was the ecoregion most affected by the crop. Regarding the assessments of the Potential Biodiversity Damage (BD) Global and Regional indicators, the Atlantic Forest and the Amazon were the ecoregions that suffered the highest impacts, mainly on plants, birds and amphibians taxa. Besides, the impacts at the global level were always more expressive than the regional ones. Due to this, we noticed that the results were influenced by the Vulnerability Score (VS). The suitability of the VS for FI is relevant and the adjustment in the equation can be suggested for other regions. Considering the results found here, to prevent regional impacts, technical measures such as extensive farming and crop rotation should be prioritized as impact mitigation actions. However, political measures tend to be more effective at geographic levels when addressing more than one ecoregion, due to the standardization of preservation procedures. Thus, from the results reported here, we conclude that the FI is relevant to diagnose measures at the administrative geographic levels of the ecoregions present in a single country, and the applied indicators reinforce that the Atlantic Forest ecoregion is the most vulnerable due to the replacement of wild forest for cultivated areas, which includes soybean crops.info:eu-repo/semantics/publishedVersio

Identificação dos sistemas agrícolas do arenito Caiuá sujeitos à erosão, através do modelo AGNPS

Mathematical models are important tools to evaluate the effect of agricultural production on waterbodies, aiming at reducing environmental degradation. Such models allow the identification of areas subjectedto erosive processes as a result of soil use and management at watershed level, which is preferable for suchinvestigations. The objective of this work was to adjust the AGNPS mathematical model, in association withthe use of GIS techniques, to predict sediment production in the Inhacanga river, in Altônia, Southern Brazil.Different scenarios were simulated and the estimates were compared with the measurements during the years ofcultivations, under different rain intensities. The areas with erosion were identified, as well as their causes andrelationships with the changes occurred in soil use and location due to alterations in the agricultural productionsystem. It was verified that the susceptibility of the areas to erosion increased as perennial crops were substitutedby annual ones and pastures. The increase in the estimated values of sediment production was proportional toclasses of soil water and energy from rain intensity, EI30. The conventional soil tillage techniques resulted incontinuous sediment carriage to the river, independently of the cultivated species.Os modelos matemáticos de simulação consistem em importante ferramenta para avaliar os efeitos daatividade agrícola sobre os recursos hídricos visando reduzir a degradação ambiental. Esses modelos identificamáreas sujeitas aos processos erosivos em função do uso e manejo do solo, em nível de bacias hidrográficas, escalaideal para tais investigações. O objetivo deste trabalho foi, a partir de dados observados, aplicar o modelo AGNPS,associado ao SIG-ArcGis, para prever a produção de sedimentos no Rio Inhacanga, Altônia, PR. Simularam-sediferentes cenários comparando-se os estimados aos medidos durante anos de cultivo, sob distintas intensidadesde chuva. Foram identificados as áreas com erosão, suas causas e o rearranjo na sua localização, em funçãodas alterações no sistema de produção agrícola. Constatou-se que a suscetibilidade à erosão aumentou sempreque as áreas ocupadas por culturas perenes foram substituídas por anuais e pastagens. O aumento dos valoresestimados de produção de sedimentos foi proporcional às classes de umidade do solo e a energia pela intensidadede chuva, o EI30. O sistema convencional de manejo resultou no carreamento contínuo de sedimentos para o rio,independentemente da espécie cultivada