Avaliação dos impactos econômicos, sociais e ambientais de tecnologias da Embrapa Pecuária Sudeste. 4. Técnicas de produção intensiva aplicadas a propriedades familiares produtoras de leite.

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Effects of liming, green manuring, and phosphate addition on electrochemical attributes of an oxisol from Central Brazil.

Highly weathered tropical soils are characterized by having a predominantly variable charge. Many management practices commonly used in the exploitation of these soils (e.g.,liming, phosphate application, and manuring) are known to modify their electrical charge and the sorption/desorption behavior of cations and anions. This process is, at least, partially governed by the charges existing in the soil system. Available information on this subject comes mainly from short-term laboratory and greenhouse experiments. There is a lack of data regarding the cumulative and long-term effects of those practices used at farm-scale levels and on the dynamics and availability of nutrients to the plants under field conditions. In the present work, changes in some electrochemical attributes of a variable charge soil (Oxisol) were studied, as influenced by treatments with phosphate + green manure (Cajanus cajan), phosphate + lime, and phosphate + lime + green manure, applied during a six-year period. In this period, rice, bean, wheat, or corn, were grown in seventeen successive crops. Phosphate (total 334 ppm P) and phosphate + lime (total 5.5 t ha -1 ) were shown to increase net electric change and soil cation exchange capacity (CEC) at the field pH, and not to affect zero point of charge (ZPC), CEC at pH 7.0, or anion exchange capacity (AEC) of the soil at the field pH. The effects of phosphate + lime were more pronounced than those of phosphate alone. Green manure (total 16 t ha -1 dry matter), associated to crop residues and phosphate or phosphate + lime, did not influence electrochemical properties.bitstream/item/207077/1/Dynia-Effects.pd

From dust bowl to dust bowl:soils are still very much a frontier of science

When the Soil Science Society of America was created, 75 yr ago, the USA was suffering from major dust storms, causing the loss of enormous amounts of topsoil as well as human lives. These catastrophic events reminded public officials that soils are essential to society’s well-being. The Soil Conservation Service was founded and farmers were encouraged to implement erosion mitigation practices. Still, many questions about soil processes remained poorly understood and controversial. In this article, we argue that the current status of soils worldwide parallels that in the USA at the beginning of the 20th century. Dust bowls and large-scale soil degradation occur over vast regions in a number of countries. Perhaps more so even than in the past, soils currently have the potential to affect populations critically in several other ways as well, from their effect on global climate change, to the toxicity of brownfield soils in urban settings. Even though our collective understanding of soil processes has experienced significant advances since 1936, many basic questions still remain unanswered, for example whether or not a switch to no-till agriculture promotes C sequestration in soils, or how to account for microscale heterogeneity in the modeling of soil organic matter transformation. Given the enormity of the challenges raised by our (ab)uses of soils, one may consider that if we do not address them rapidly, and in the process heed the example of U.S. public officials in the 1930s who took swift action, humanity may not get a chance to explore other frontiers of science in the future. From this perspective, insistence on the fact that soils are critical to life on earth, and indeed to the survival of humans, may again stimulate interest in soils among the public, generate support for soil research, and attract new generations of students to study soils

High genetic diversity but low population structure in the frog Pseudopaludicola falcipes (Hensel, 1867) (Amphibia, Anura) from the Pampas of South America

Relative to South America’s ecoregions, the temperate grasslands of the Pampas have been poorly studied from a phylogeographic perspective. Based on an intermediate biogeographic setting between subtropical forest (Atlantic Forest) and arid ecosystems (Chaco and Patagonia), Pampean species are expected to show unstable demographic histories due to the Quaternary climatic oscillations. Herein, we investigate the phylogenetic relatedness and phylogeographic history of Pseudopaludicola falcipes, a small and common frog that is widely distributed across the Pampean grasslands. First, we use molecular data to assess if P. falcipes represents a single or multiple, separately evolving cryptic lineages. Because P. falcipes is a small-size species (\u3c20 mm) with extensive coloration and morphological variation, we suspected that it might represent a complex of cryptic species. In addition, we expected strong genetic and geographic structuring within Pseudopaludicola falcipes due to its large geographic distribution, potentially short dis- persal distances, and multiple riverine barriers. We found that P. falcipes is a single evolutionary lineage with poor geographic structuring. Furthermore, current populations of P. falcipes have a large effective population size, maintain ancestral polymorphisms, and have a complex network of gene flow. We conclude that the demographic history of P. falcipes, combined with its ecological attributes and the landscape features of the Pampas, favored a unique combination among anurans of small body size, large population size, high genetic variability, but high cohesiveness of populations over a wide geographic distribution

ARE Leptodactylus didymus AND L. mystaceus PHYLOGENETICALLY SIBLING SPECIES (AMPHIBIA, ANURA, LEPTODACTYLIDAE)?

The Leptodactylus fuscus species group consists of 25 currently recognized species; within this species group and distributed throughout the Amazon Basin, Atlantic Forests, Gran Chaco, and cerrados is the L. mystaceus species complex. This species complex consists of L. didymus, L. elenae, L. mystaceus, L. notoaktites, and L. spixi. Adult morphologies have been used to distinguish these species from each other except for L. didymus and L. mystaceus (Heyer, 1978; Heyer et al., 1996). Leptodactylus didymus and L. mystaceus are morphologically indistinguishable; the species are recognizable only by the characteristics of their advertisement calls: non-pulsed in L. didymus and pulsed in L. mystaceus (Heyer et al., 1996). Traditionally, L. mystaceus and L. didymus have been considered sibling species. The concept of sibling species was originally introduced by Mayr (1942: 151) to describe pairs or groups of morphologically identical or nearly identical species; however, in subsequent work Mayr (1976) interchangeably used the terms sibling and cryptic species to describe morphologically similar species. Mayr (1942: 151) considered sibling species to be important in understanding the full complexity of animal speciation. In order to differentiate these two terms, herein we take a narrow cladistic methodological approach (i.e., dichotomous speciation) by which we restrict the term sibling species to two taxa that share a most recent common ancestor; whereas, the term cryptic (derived from the Greek Kruptos, meaning \u27hidden\u27; Allaby, 1991) species refers to hidden diversity and does not necessarily imply close phylogenetic relationship. Thus, the sibling species pair of L. didymus and L. mystaceus assumes two postulates: (1) the taxa shared a most recent common ancestor not shared with other species in the L. mystaceus species complex and (2) the two taxa could represent a recent speciation event (i.e., not enough time has passed to reach morphological differentiation, although this is not a requisite). Herein, we analyze the genetic diversity among taxa in this species complex to determine if the sibling species L. didymus and L. mystaceus are sister taxa. If the assumptions about sibling species are correct, then we would expect that the two taxa involved would be genetically closer between themselves than with any other closely related species

Selection of rice cultivars resistant to some pathogens using seed health testing

Trinta e seis progênies de arroz (Oryza sativa L) irrigado foram testadas, em campo, objetivando-se determinar os fungos mais importantes de sementes e o desempenho das progênies com relação a esses patógenos, dando-se ênfase especial à descoloração e consequente perda de peso de sementes. Observaram-se diferenças significativas entre progênies quanto à presença de sete fungos de sementes. Entretanto, considerando-se a descoloração e a consequente perda de peso de sementes, Rhynchosporium oryzae, Phoma spp., Trichoconis padwickii e Helminthosporium oryzae se apresentaram como patógenos mais nocivos. Em todos os parâmetros analisados, sete progênies suplantaram a cultivar comercial IAC-899, usada como controle. Conclui-se que, apesar de trabalhoso, o teste de sanidade de sementes é um instrumento muito eficaz na seleção de novos germoplasmas de arroz com baixa incidência de fungos de sementes.Thirty-six lowland rice (Oryza sativa L.) progenies have been tested in yield trials aiming at determining the most important seed-borne fungi and the progeny performance as to each of the pathogens found in seeds, with special emphasis on seed discoloration and consequent seed weight loss. Significant progeny differences as to seven seed-born fungi have been found; however, as far as seed discoloration and consequent seed weight loss are concerned, Rhynchosporium oryzae, Phoma spp., Trichoconis padwickii and Helminthosporium oryzae have been the most important pathogens. Seven progenies outperformed IAC-899 (commercial variety used as control) regarding all the parameters analysed. It is concluded that seed health testing is an effective complementary 1001 in selecting rice germplasms with lower seed-borne fungal incidence

Copper phytoextraction and phytostabilization by Brachiaria decumbens Stapf. in vineyard soils and a copper mining waste.

Brachiaria decumbens is a high biomass plant with great potential for phytoremediation of copper-polluted soils. The current study aimed to evaluate B. decumbens plants for phytoextraction and phytostabilization use in two different copper contaminated vineyard soils and a copper mining waste. Also, the macro and micronutrients uptake were evalu- ated after plants growth in copper contaminated soils. B. decumbens was cultivated in two vineyard soils (Inceptisol and Mollisol) and a copper mining waste for 47 days of growth in greenhouse. Then, B. decumbens?s nutrient uptake was evaluated, and it?s potential application in phytoremediation techniques for the phytoextraction and phytostabilization of copper contamination. B. decumbens exhibited high levels of biomass production at contaminated soils and no negative effect on macronutrients uptake was found. Copper contaminated soils affected micronutrients uptake by Brachiaria plants. This Brachiaria specie showed high potential on copper phytoextraction with accumulation of copper concentra- tions in the shoots and roots of 70 and 585 mg·kg?1 of dry mass, respectively, in the vineyard Inceptisol soil, after 47 days of growth. Mollisol soil and copper mining waste also exhibited high copper concentration in the biomass in the entire plant with 371 and 466 mg·kg?1, respectively. Although Brachiaria exhibited low levels of translocation factor for copper, this specie showed high potential for copper phytoextraction on Inceptisol, Mollisol and copper mining waste with 1900, 1156 and 1363 g·ha?1 of copper, respectively. In summary, B. decumbens plants showed high potential for copper phytoextraction and phytostabilization of copper on contaminated vineyard soils and copper mining waste