Variabilidade espacial de atributos químicos do solo sob diferentes usos e manejos Spatial variability of chemical attributes of a soil under different uses and managements

O uso e manejo do solo e da cultura são importantes condicionadores da variabilidade de atributos do solo. O trabalho foi desenvolvido em Selvíria (MS), com o objetivo de avaliar a variabilidade espacial do pH, potássio (K), cálcio (Ca), magnésio (Mg) e saturação por bases (V) em Latossolo Vermelho sob diferentes usos e manejos. Os solos foram amostrados em malha, com intervalos regulares de 2 m, perfazendo o total de 64 pontos, nas profundidades de 0,0-0,1 e 0,1-0,2 m, nas seguintes áreas: vegetação natural (Cerrado), plantio direto, plantio convencional e pastagem. As maiores variabilidades, medidas por meio do coeficiente de variação, foram observadas para K, Mg e Ca; o pH apresentou o menor coeficiente de variação nos diferentes usos e manejo do solo, e o atributo V, coeficiente de variação médio. Os sistemas preparo convencional e pastagem apresentaram os menores alcances quando comparado aos sistemas Cerrado e plantio direto.<br>The use and management of soil and crop condition the variability of soil attributes directly. This study was conducted in Selvíria-MS, Brazil with the objective of evaluating the spatial variability of pH, potassium (K), calcium (Ca), magnesium (Mg) and base saturation (% BS) in an Oxisol under different use and management conditions. Soil samples were collected in a grid, in regular 2 m intervals, at 64 grid points, at depths of 0.0-0.1 m and 0.1-0.2 m, from areas of: native cerrado vegetation (savannah), annual crops under no-tillage, annual crops under conventional tillage, and pasture. The highest variabilities, as determined by the coefficient of variation, were observed for K, Mg and Ca, while the lowest coefficient of variation was found for pH in the different uses and management conditions. A medium coefficient of variation was observed for the %BS. The ranges of soils under conventional tillage and pasture systems were smaller than those under native vegetation and no-tillage

Variabilidade espacial de MO, P, K e CTC do solo sob diferentes usos e manejos Spatial variability of MO, P, K and CTC of soil under different use and management conditions

O estudo da variabilidade espacial dos atributos químicos dos solos é particularmente importante em áreas onde o solo está submetido a diferentes manejos. O trabalho foi desenvolvido em Selvíria (MS), com o objetivo de avaliar a variabilidade espacial da matéria orgânica (MO), o fósforo (P), do potássio (K) e a capacidade de troca catiônica (CTC) em um Latossolo Vermelho distrófico sob diferentes usos e manejos. Os solos foram amostrados em uma malha, com intervalos regulares de 2m, perfazendo um total de 64 pontos, nas profundidades de 0,0-0,1m e 0,1-0,2m, nas seguintes áreas: vegetação natural (cerrado), plantio direto, plantio convencional e pastagem. O sistema de plantio direto apresentou acúmulo significativo de matéria orgânica, fósforo, potássio e elevação da CTC em relação aos demais sistemas estudados, além da melhoria nas condições químicas do solo. A matéria orgânica foi maior em relação ao sistema natural. As maiores variabilidades medidas por meio do coeficiente de variação foram observadas para o fósforo e o potássio, sendo que a matéria orgânica e a CTC apresentaram coeficiente de variação médio nos diferentes usos e manejos do solo.<br>The study of the spatial variability of the chemical attributes of the soils is particularly important in areas where the soil is submitted to different management. This work was developed in Selvíria (MS) with the objective of evaluating the spatial variability of the organic matter (MO), phosphorus (P), potassium (K) and cation exchange capacity (CEC) in a oxisol under different use and management conditions. The soils were collected in a grid, with regular intervals of 2m, total of 64 points, in the depths of 0,0-0,1m and 0,1-0,2m, in the use and management were: native vegetation (savannah), no-tillage, conventional system and pasture. The system of no-tillage presented significant accumulation of organic matter, phosphorus, potassium and elevation of CEC in relation to the other studied systems, besides the improvement in the chemical conditions of the soil, the organic matter was larger in relation to the natural system. The largest variabilities measured through the variation coefficient, they were observed for the phosphorus and potassium, and the organic matter and CEC presented medium variation coefficient in the different uses and management of the soil

Variabilidade espacial dos teores de macronutrientes em latossolos sob sistema plantio direto Spatial variability of macronutrient contents in untilled oxisols

A eficácia dos planos de amostragem do solo pode ser aumentada se for conhecida e considerada a variabilidade espacial de seus atributos, e, para isso, devem ser estudados os fatores que a determinam. O objetivo deste trabalho foi avaliar a variabilidade espacial dos teores de macronutrientes P, K, Ca, Mg e S em dois Latossolos, um muito argiloso e outro de textura média, cultivados com manejo semelhante, há oito anos sob sistema plantio direto. A coleta das amostras do solo foi realizada em intervalos regulares de 50 m, totalizando 121 pontos, em duas camadas (0-10 e 10-20 cm). Os dados foram avaliados por estatística descritiva e geoestatística, com base no ajuste de semivariogramas. Verificou-se que a dependência espacial varia conforme o elemento, a textura do solo e a profundidade de coleta da amostra. Assim, o Latossolo de textura média, de maneira geral, apresentou maior variabilidade espacial para os teores dos nutrientes em relação ao de textura muito argilosa. A camada de 0-10 cm, nos dois Latossolos, proporcionou maior variabilidade espacial para os teores dos nutrientes avaliados. A análise de dependência espacial mostrou que, nos dois solos e nas duas camadas, a maioria dos nutrientes estudados apresentou moderada correlação espacial. Os modelos de semivariogramas ajustados foram o exponencial e o esférico, sendo o primeiro em maior quantidade. Maiores teores de todos os macronutrientes avaliados foram verificados nos primeiros 10 cm do solo. Os valores de alcance da dependência espacial foram menores no Latossolo de textura média, variando de 9 a 29 m; no de textura muito argilosa eles variaram de 31 a 399 m. Se for adotada a geoestatística no esquema de amostragem, o número de amostras a serem coletadas será menor no Latossolo de textura muito argilosa, devido aos maiores valores do alcance apresentados por todas as variáveis.<br>The effectiveness of soil sampling plans may be increased if the spatial variability of soil properties is known and taken into consideration; the factors that determine it should therefore be studied. The objective of this paper was to evaluate the spatial variability of the contents P, K, Ca, Mg, and S in two Oxisols, one very clayey and the other with medium texture, managed in a similar system for eight years, in no-tillage. Soil samples were collected at regular distances of 50 m, totaling 121 points in two layers (0-10 and 10-20 cm). The data were analyzed with descriptive statistics and geostatistics, based on the adjustment of semivariograms. It was found that spatial dependence varies with the nutrient, soil texture and sampling depth. Thus, the spatial variability of the medium texture Oxisol for nutrient levels was generally greater than of the very clayey Oxisol. The spatial variability for nutrient levels was highest in both Oxisols in the 0-10 cm layer. The analysis of spatial dependence showed that the spatial correlation in both soils and both layers was moderate for most nutrients studied. Exponential and spherical semivariogram models were adjusted, the first in greater quantity. Highest amounts of all nutrients were detected in the top 10 cm of soil. The range of spatial dependence in the medium texture Oxisol was lower (9-29 m) than in the very clayey Oxisol (31-399 m). If adopted in a geostatistical sampling scheme, the number of samples to be collected will be lower in the very clayey soil, due to the wider range of all variables

Impact of COVID-19 on Cardiovascular Testing in the United States Versus the Rest of the World

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-U.S. institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p &lt; 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection