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

Long-term effect of different soil management systems and winter crops on soil acidity and vertical distribution of nutrients in a Brazilian Oxisol

“Strategies” to sustain crop productivity by reducing the fertilizer and lime demands must be developed. The use of plant species that use more efficiently the soil nutrients and tillage systems that provide nutrients accumulation in more labile forms are prerequisites for sustainable agroecosystems. This study aimed to evaluate the long period effect of cultivating different winter species under different soil management systems on vertical distribution of soil nutrients and the soil acidity distribution in soil profile. The experiment was established in 1986 with six winter treatments (blue lupine, hairy vetch, oat, radish, wheat and fallow) under conventional tillage (CT) and no-tillage (NT) in a very clayey Rhodic Hapludox in Southern Brazil. As a result of 19 years of no soil disturbance, soil chemical attributes related to soil acidity and the availability of P and K were more favorable to crops growth up to 10 cm in the soil under no-tillage than in the conventional tillage. On other hand, lime applications in low doses on the soil surface were not efficient in neutralizing the aluminum toxicity below 10 cm depth. It shows that repeated use of lime on the soil surface under NT system can be a viable alternative strategy only when soil acidity and aluminum toxicity in subsurface has been previously eliminated using the adequate amount of lime and incorporating it into the arable layer. Moreover, in the conventional tillage system P and K availability were higher below 10 cm depth compared to the no-tillage system. Even after 19 years of no soil disturbance in the NT system the available P content below 10 cm soil layer was lower than the optimal content of available P recommended to cash crops. The reduced surface K application over time was sufficient to gain adequate crop yields and to maintain the optimal content of soil available K in both soil management systems. The effects of soil management systems were predominant on the soil acidity attributes, and no effects of winter cover crops were observed on soil acidity attributes. Black oat and blue lupine were more efficient in P cycling, increasing the soil available P content especially in the surface soil under NT. The lower amount of biomass produced over time when no cover crops were used in the winter period resulted in lower P and K availability in the soil, showing the important role of growing winter species to maintain soil fertility

As plantas daninhas e a semeadura direta.

Comportamento das plantas daninhas; Métodos de controle; Tecnologia da aplicação; Novas abordagens.bitstream/CNPSO/18514/1/circtec33.pd

Soil structure and its influence on microbial biomass.

Soil and crop management have a fundamental role in the maintenance and improvement of soil quality, as they have a direct influence its structure and on microorganisms habitats. The aim of this study was to quantify carbon and nitrogen microbial biomass in the HMUs in a dystroferric Red Latosol, in a 22-year experiment with treatments consisting of a no-tillage planting system (NT), no-tillage with chiseling every three years (NTC) and conventional tillage (CT), using crop rotation (CR) and succession (CS) systems, in order to determine the relationship between alterations in soil structure and modifications in the contents of microbial biomass. Significantly higher levels of carbon and nitrogen microbial biomass (CMB and NMB) were observed in the HMUs in NT and NTC systems under both CR and CS. On average, HMUs in the NT and NTC treatments presented 20% more CMB and 51% more NMB that in the CT treatment. NMB was the parameter most highly affected by the soil management. At depths of 0?20 cm, total organic carbon (TOC), was higher by an average of 21% than in the NT and NTC treatments. Total nitrogen (TN) was also affected by the soil management. This demonstrates how the tillage of the soil exposes the organic matter in the aggregates to oxidation and nitrogen mineralization

Qualidade físico-hídrica de cambissolo sob pastagem extensiva.

O objetivo deste trabalho foi analisar o efeito de pastagem extensiva com Brachiaria decumbens sobre a qualidade física de dois Cambissolos, originados de Micaxisto e Gnaisse-Granítico Leucocrático. As amostras de solo foram coletadas em 08 trincheiras totais localizadas no topo, meia-encosta e baixadas em topossequências nas camadas 0-10, 10-20, 20-40, 40-60cm. Os sistemas de pastagens extensivas em Cambissolos com diferentes materiais de origem provocam alteração na qualidade físico-hídrica do solo na profundidade de 0-10 cm. A área de Micaxisto apresenta textura arenosa nas camadas de 0-10 e 10-20 cm e textura média nas camadas de 20-40 cm e 40-60 cm sendo indicativo de processos erosivos e migração da argila para as camadas mais profundas. A área de Gnaisse-Granítico Leucocrático apresenta textura média em todas as profundidades, maiores teores de silte e areia fina, maior densidade nas camadas de 0-10 e 40-60 cm, baixa macroporosidade em todas as profundidades sendo mais susceptível à erosão em relação à área de Micaxisto. Os atributos físicos estudados apresentaram bom desempenho como indicadores da qualidade do solo