Análise de componentes principais de atributos químicos e físicos do solo limitantes à produtividade de grãos.

O objetivo deste trabalho foi avaliar, por meio da análise dos componentes principais, a redução na dimensionalidade de atributos químicos e físicos do solo para a compreensão da variabilidade espacial e temporal da produtividade de culturas de grãos. A área experimental, de 54 ha, é manejada em agricultura de precisão há oito anos. Com base em seis mapas de colheita (soja - safra 2000/2001; milho - 2001/2002; soja - 2002/2003; trigo - 2003; soja - 2003/2004; e milho - 2004/2005), a área foi dividida em três zonas de produtividade de grãos (alta, média e baixa). Foram definidos 15 pontos georreferenciados representativos, para determinação de atributos químicos e físicos do solo, o que totalizou 63 variáveis analisadas. Entre os atributos químicos, o elevado teor de K no solo é o que melhor explica a variabilidade espacial da produtividade das culturas de grãos, provavelmente em razão do desbalanço das relações Ca:K e Mg:K. A zona de baixa produtividade apresentou baixa qualidade física do solo. Neste caso, a infiltração de água no solo, isoladamente, é a variável que melhor explica o desempenho das culturas de grãos. A análise dos componentes principais dos atributos químicos e físicos do solo é estratégia eficiente para explicar a variabilidade espacial e temporal da produtividade de culturas de grãos

Once-monthly paliperidone palmitate in recently diagnosed and chronic non-acute patients with schizophrenia

OBJECTIVE: To explore the treatment response, tolerability and safety of once-monthly paliperidone palmitate (PP1M) in non-acute patients switched to oral antipsychotics stratified by time since diagnosis as recently diagnosed (3 years). RESEARCH DESIGN AND METHODS: Post-hoc analysis of a prospective, interventional, single-arm, multicentre, open-label, 6-month study performed in 233 recently diagnosed and 360 chronic patients. MAIN OUTCOME MEASURES: The proportion achieving treatment response (defined as >/=20% improvement in Positive and Negative Syndrome Scale [PANSS] total score from baseline to endpoint) and maintained efficacy (defined as non-inferiority in the change in PANSS total score at endpoint [Schuirmann's test]). RESULTS: 71.4% of recently diagnosed and 59.2% of chronic patients showed a >/=20% decrease in PANSS total score (p=0.0028 between groups). Changes in PANSS Marder factors, PANSS subscales, and the proportion of patients with a Personal and Social Performance scale (PSP) total score of 71-100 were significantly greater in recently diagnosed compared with chronic patients. PP1M was well tolerated, presenting no new safety signals. CONCLUSION: These data show that recently diagnosed patients treated with PP1M had a significantly higher treatment response and improved functioning, as assessed by the PSP total score, than chronic patients

Infective endocarditis in intravenous drug abusers: an update

Infective endocarditis despite advances in diagnosis remains a common cause of hospitalization, with high morbidity and mortality rates. Through literature review it is possible to conclude that polymicrobial endocarditis occurs mainly in intravenous drug abusers with predominance in the right side of the heart, often with tricuspid valve involvement. This fact can be associated with the type of drug used by the patients; therefore, knowledge of the patient's history is critical for adjustment of the therapy. It is also important to emphasize that the most common combinations of organisms in polymicrobial infective endocarditis are: Staphylococcus aureus, Streptococcus pneumonia and Pseudomonas aeruginosa, as well as mixed cultures of Candida spp. and bacteria. A better understanding of the epidemiology and associated risk factors are required in order to develop an efficient therapy, although PE studies are difficult to perform due to the rarity of cases and lack of prospective cohorts.This work was supported by Portuguese Foundation for Science and Technology (FCT) through the grants SFRH/BPD/47693/2008, SFRH/BPD/20987/2004 and SFRH/BPD/72632/2010 attributed to Claudia Sousa, Claudia Botelho and Diana Rodrigues, respectively

A Soil Management Assessment Framework (SMAF) Evaluation of Brazilian Sugarcane Expansion on Soil Quality

The Soil Management Assessment Framework (SMAF) was developed to evaluate impacts of land use and management practices on soil quality (SQ), but its suitability for Brazilian tropical soils was unknown. We hypothesized that SMAF would be sensitive enough to detect SQ changes associated with sugarcane (Saccharum officinarum L.) expansion for ethanol production. Field studies were performed at three sites across the south-central region of Brazil, aiming to quantify the impacts of a land use change sequence (i.e., native vegetation–pasture–sugarcane) on SQ. Eight soil indicators were individually scored using SMAF curves developed primarily for North American soils and integrated into an overall Soil Quality Index (SQI) and its chemical, physical, and biological sectors. The SMAF scores were correlated with two other approaches used to assess SQ changes, soil organic C (SOC) stocks and Visual Evaluation of Soil Structure (VESS) scores. Our findings showed that the SMAF was an efficient tool for assessing land use change effects on the SQ of Brazilian tropical soils. The SMAF scoring curves developed using robust algorithms allowed proper assignment of scores for the soil chemical, physical, and biological indicators assessed. The SQI scores were significantly correlated with SOC stocks and VESS scores. Long-term transition from native vegetation to extensive pasture promoted significant decreases in soil chemical, physical, and biological indicators. Overall SQI suggested that soils under native vegetation were functioning at 87% of their potential capacity, while pasture soils were functioning at 70%. Conversions of pasture to sugarcane induced slight improvements in SQ, primarily because of improved soil fertility. Sugarcane soils are functioning at 74% of their potential capacity. Based on this study, management strategies were developed to improve SQ and the sustainability of sugarcane production in Brazil

Sugarcane Straw Blanket Management Effects on Plant Growth, Development, and Yield in Southeastern Brazil

In Brazilian sugarcane (Saccharum spp.) production systems, the practice of moving harvesting residue from row to inter-row positions (i.e., raking) has increased in response to producer concerns over the potential negative effects of sugarcane straw on crop establishment and stalk yield. Despite increasing adoption among sugarcane farmers, the impacts of straw raking practices on plant growth and yield remain unclear. A 2-yr experiment that included both dry and wet seasons was conducted at two sites in southeastern Brazil to evaluate straw management strategy effects on plant tillering, phytomass accumulation, plant nutritional status, and stalk yield. The experiments were established at the Bom Retiro mill and the Univalem mill. Experimental treatments included raking straw to inter-rows (raked), total straw removal (bare soil), and no straw removal (straw cover). Raked and bare soil treatments improved plant tillering but did not influence final plant population. Straw management had a slight effect on phytomass accumulation. Reduction of phytomass yield was observed from the first to the second ratoon during both seasons at both sites. At Bom Retiro, phytomass yield decreased 37% for stands established during the dry season and 19% for stands established during the wet season. At Univalem, phytomass yield decreased 20% for stands established during the dry season and 30% for stands established during the wet season. Retaining straw in the field (regardless of treatment) increased leaf tissue P content but not stalk yield. Raking straw from row to interrow positions at these locations in southeastern Brazil had no benefit on sugarcane yield but may result in soil compaction and higher production costs over time

Tree component influences soil carbon storage and litter decomposition in agrosilvopastoral system.

Integrated farming systems are recognized as agricultural production models that enhance soil carbon storage. This study aimed to evaluate the influence of the tree component on the litter dynamics and soil C and N stocks in an agrosilvopastoral system in the Brazilian Cerrado. We compared nine-years-old agrosilvopastoral system (ASP) with an arrangement of 3x2+14m, with a 24-years-old nominal pasture (NP) and a native vegetation (NV). Five treatments including three sampling points in ASP [between the eucalyptus trees (P1), in the canopy projection area (P2) and in the middle of the alley (P3)], and two areas (PN and VN) were evaluated. Litterfall production from eucalyptus were evaluated in suspended collectors while the decomposition rate was evaluated in litterbags. The assessments were carried out monthly over one year, as well as CO2 fluxes. Soil samples were taken at six soil layers until 0.5m depth to evaluate bulk density, soil fertility and soil C and N stocks. The litterfall production higher in P1, with decrease during the dry season. P1 and P3 showed higher decomposition rates, with final remaining mass of 28.71 and 32.33%. CO2 efflux was higher in the rainy season and showed similar pattern between P1 e NV. Regarding the soil fertility, NV showed higher values of macronutrients and base saturation, and these results can be associated to the nutrient exportation and the deficit of fertilization management in ASP and NP. Soil C and N stocks at 0-50 cm depth were higher in NV (115.4 and 11.3 Mg ha-1), followed by NP (92.4 and 8 .8 Mg ha-1) and ASP (89.9 and 9.0 Mg ha-1). In the sampled points within ASP, soil C and N stocks were higher in P1, showing the influence of tree component. Our results showed that the arrangement as well as the management of eucalyptus trees in the integrated farming system influenced the dynamics of litter decomposition and soil C and N storage over time

Straw removal effects on sugarcane root system and stalk yield.

The sugarcane (Saccharum spp. L.) mechanical harvesting system leaves a large amount of straw mulch on the soil surface. The straw mulch may affect soil conditions, root regrowth, and sugarcane yield. Thus, this study assessed the response of sugarcane root system growth and stalk yield to different rates of straw removal. An experiment was conducted in a Rhodic Kandiudox with sand clay loam texture to test the impact of four rates of straw removal: no removal (18.9 Mg ha−1 of dry mass); moderate removal (8.7 Mg ha−1); high removal (4.2 Mg ha−1) and total removal on sugarcane root system and stalk yield. Higher concentrations of roots (60%) were found in the first 40 cm of soil. Moderate straw removal resulted in higher root mass (3.6 Mg ha−1 ) and stalk production (23 Mg ha−1 of dry mass). However, no straw removal reduced root mass by 20% (105 Mg ha−1). Through regression analysis, it was estimated that retaining between 8.5 and 13 Mg ha−1 of straw resulted in the highest root mass and stalk yield. Managing straw removal to retain a moderate amount enables producers to sustain suitable soil conditions for sugarcane root growth and stalk production while providing straw for industrial use

Maize-Urochloa grass intercropping: an option for improving sustainable agriculture in the Brazilian Savannah.

Intercropping annual cash crops with grasses is a strategy that promotes both diversification and intensification of production in the same area, contributing to sustainable food systems. This study evaluated the impact of intercropping maize with different Urochloa species on maize and subsequent soybean yields over three years in the Brazilian Savannah. The treatments included: (1) maize monoculture; (2) maize intercropped with Urochloa ruziziensis; (3) maize intercropped with U. brizantha cv. Marandu; and (4) maize intercropped with U. brizantha cv. BRS Paiaguás. The evaluations included maize grain yield, land equivalent ratio (LER), forage biomass and soybean yield in succession. The results confirmed that maize intercropped with U. brizantha cv. Marandu and U. brizantha cv. BRS Paiaguás achieved grain yields comparable to monoculture. Demonstrating that these forage species do not significantly compete with maize in 2018 and 2019 in Montividiu and 2018 and 2020 in Rio Verde. In Montividiu, intercropping with U. brizantha cv. BRS Paiaguás resulted in an average LER of 1.13 over three years, highlighting its advantage in optimising land use. In addition, the intercropping system was particularly beneficial in sandy soils, where faster biomass decomposition accelerated improvements in soil structure, moisture retention, and nutrient availability, leading to earlier benefits in soybeans grain yield compared to clay soils. These findings emphasise the potential of maize-forage intercropping to enhance land-use efficiency and soil health while maintaining crop yields in tropical agroecosystems. However, site-specific management is essential to maximise benefits and minimise trade-offs. Future research should focus on long-term soil health dynamics and refining intercropping strategies to improve sustainability in different environmental conditions

A Soil Management Assessment Framework (SMAF) Evaluation of Brazilian Sugarcane Expansion on Soil Quality

The Soil Management Assessment Framework (SMAF) was developed to evaluate impacts of land use and management practices on soil quality (SQ), but its suitability for Brazilian tropical soils was unknown. We hypothesized that SMAF would be sensitive enough to detect SQ changes associated with sugarcane (Saccharum officinarum L.) expansion for ethanol production. Field studies were performed at three sites across the south-central region of Brazil, aiming to quantify the impacts of a land use change sequence (i.e., native vegetation–pasture–sugarcane) on SQ. Eight soil indicators were individually scored using SMAF curves developed primarily for North American soils and integrated into an overall Soil Quality Index (SQI) and its chemical, physical, and biological sectors. The SMAF scores were correlated with two other approaches used to assess SQ changes, soil organic C (SOC) stocks and Visual Evaluation of Soil Structure (VESS) scores. Our findings showed that the SMAF was an efficient tool for assessing land use change effects on the SQ of Brazilian tropical soils. The SMAF scoring curves developed using robust algorithms allowed proper assignment of scores for the soil chemical, physical, and biological indicators assessed. The SQI scores were significantly correlated with SOC stocks and VESS scores. Long-term transition from native vegetation to extensive pasture promoted significant decreases in soil chemical, physical, and biological indicators. Overall SQI suggested that soils under native vegetation were functioning at 87% of their potential capacity, while pasture soils were functioning at 70%. Conversions of pasture to sugarcane induced slight improvements in SQ, primarily because of improved soil fertility. Sugarcane soils are functioning at 74% of their potential capacity. Based on this study, management strategies were developed to improve SQ and the sustainability of sugarcane production in Brazil