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

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

Eficiência Relativa de Agricultores Familiares na Produção de Leite.

O objetivo deste trabalho foi avaliar a eficiência relativa na produção de leite de uma amostra de agricultores familiares do Estado do Paraná, que estão sob orientação técnica de extensionistas participantes do Projeto Balde Cheio. A avaliação foi feita utilizando-se o Método de Envelopamento de Dados ? DEA. A média da eficiência da amostra analisada foi de 92% evidenciando que o grupo de produtores foi muito eficiente na gestão da tecnologia empregada e a importância do extensionista como agente de transferência de tecnologia

Grupos de compatibilidade de isolados de Phytophthora nicotianae de acácia-negra.

Resumo

Impacto social de inovações tecnológicas na agricultura familiar: tecnologias para produção de leite.

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Efeitos da adubação fosfatada e da calagem sobre a adsorção de fósforo em um Latossolo Vermelho-Escuro.

Avaliou-se o efeito da aplicação sequencial de fósforo (como adubação de manutenção), e de fósforo + cálcio, sobre parâmetros de adsorção de fósforo de um Latossolo Vermelho-Escuro argiloso de cerrado. Foram aplicados 1.530 kg do P2 O5 /ha e 5,5 t/ha de calcário ao longo de 17 cultivos alternados de arroz (5), feijão (6), trigo (4) e milho (2), realizados num período de seis anos e meio. O P foi aplicado parceladamente, na dose de 90 kg P2 O5/ha por cultivo e calcário, em duas vezes: 2,5t/ha antes do primeiro cultivo e 3,0 t/ha entre o nono e o decimo cultivos. Os tratamentos com adubação fosfatada e adubação fosfatada mais calagem reduziram significativamente a capacidade máxima de adsorção de fosforo do solo, mas não afetaram a energia de ligação fósforo-solo

Necessidade de instrumentação para monitorar nitrato no perfil de solo, em tempo real.

No município de São Carlos, SP na Fazenda canchim, do Centro de Pesquisa de Pecuária do Sudeste (CPPSE/EMBRAPA), entre cotas altimétricas de 680 e 911m, sob clima tropical de altitude, e conduzido um sistema intensivo de produção de leite de bovinos a pasto, com pastejo totacionado no período das águas (out/nov-mar/abr), na cabeceira da microbacia do ribeirão Canchim. O solo e latossolo vermelho-amarelo arenoso, originalmente distrófico, manejado com tobiata (Panicum maximum), recebendo elevada dose de fertilizante nitrogenado mineral. O monitoramento de teor de nitrato em uma destas áreas revelou que: 1) os teores de nitrato variam entre 9 e 33 mg dm, faixa verificada na literatura, apesar da alta dose de fertilizante nitrogenado aplicada, 2) existe dificuldade no monitoramneto de nitrato em solos, devido a problemas com amostragem de terra, 3) ocorre grande variabilidade nos teores de nitrato em curto espaço de tempo, que necessita ser melhor estudada, para que possa haver melhor gerenciamento de atividades agrícolas de precisão

Algoritmo computacional para determinar o perfil mínimo de marcadores moleculares que discriminam um conjunto de cultivares.

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Canchim's watershed as a natural laboratoriy for assessment and fostering the sustainable management of cattle farms in the tropics.

Canchim's watershed is compised into an 1496 ha (14,96 km2) area located between the geografical coordenates of 21o55' and 22o00'S, and47o48'and 47o52'W. The climate is classified as Cwa (Koeppen), warm with fry winter. Annual mean of reainfall is 1354 mm, with 1525 mm of potential evapotranspiration. Dry season extends from april to september.URL: http://www.fao.org/WAICENT/FAOINFO/SUSTENDEV/agr99/agr0003.htm (1abr.1999)

Spatial and temporal variation of near surface soil moisture and soil temperature in integrated crop-livestock system.

The objective of this study were to evaluate the spatial and temporal distribution of near surface soil moisture and soil temperature over a growing season in soybean/corn and grass under integrated crop-livestock systems