Irrigation water strategies for the Buriti Vermelho watershed: towards a higher water productivity.

RESUMO: Com a necessidade de se utilizar a água de forma cada vez mais eficientemente, faz necessário melhorar a produtividade de uso da água em escala de bacia hidrográfica. Este estudo objetivou avaliar a produtividade de uso da água e a possibilidade de aumentar a área irrigada na bacia hidrográfica do Buriti Vermelho, Brasil. o modelo de Solo-Água-Atmosfera-Planta (SWAP) foi utilizado nas simulações. A bacia do Buriti Vermelho possui agricultura de sequeiro (soja e milho), e irrigada (milho, feijão e trigo). A produtividade de uso da água (CWP) foi calculada em função da lâmina total de água aplicada, que inclui a soma da irrigação e da precipitação. Avaliou-se também o período ideal para o plantio da soja, buscando-se o rendimento ótimo e a maior CWP. A CWP variou de 0,32 kg m-3, para a cultura da soja, a 1,90 kg m-3 para o trigo. Para o período estudado houve uma redução da CWP com o aumento da lâmina de irrigação. A irrigação mostrou ter grande influência no rendimento das culturas do feijão, do trigo e do milho. O rendimento ótimo e a máxima produtividade de uso da água para a soja foram observados no mês de novembro. O cenário futuro mostrou que haverá decréscimo na CWP e que será necessário aplicar mais água para se conseguir as mesmas produtividades. ABSTRACT: As water is required to be used more efficiently, the crop water productivity should be improved. The main objective of this paper was to assess both the crop water productivity and the possibility to expand irrigated land in the Buriti Vermelho experimental watershed, Brazil. Soil-Water-Atmosphere-Plant (SWAP) model was used to perform the analysis. Buriti Vermelho contains both rain fed (soybean and corn) and irrigated (corn, common beans and wheat) crops. The crop water productivity was calculated as a function of total applied water, which includes the sum of irrigation and precipitation. An additional study was performed to verify the most ideal rainfed soybean growth period. The crop water productivity varied from 0.32 kg m-3 for soybeans to 1.90 kg m-3 for wheat. The crop water productivity decreased when the irrigation amount increased. Irrigation showed to have a big influence on the crop yield of common beans, wheat and rainfed corn, caused by a combination of low rainfall and low actual evapotranspiration values with higher irrigation requirements. The results showed November as being the most optimal growth period for soybeans. This month showed both the optimal yield as maximum crop water productivity. The future forecasts a decrease in crop water productivity, what means more water will be needed to reach the same amount of crop yield

Veterinary antibiotic usage in the Netherlands in 2010

The objective of this study is to obtain detailed insight into the exposure of farm animals to antibiotics, by monitoring both sales data at the national level and more specifically data per animal species. The results of the study can be used by the Ministry of Economic Affairs, Agriculture and Innovation for policy evaluation. In addition, the usage data might play a role in explaining trends in resistance that have become apparent

Blood pressures, heart rate and locomotor activity during salt loading and angiotensin II infusion in protease-activated receptor 2 (PAR2) knockout mice

<p>Abstract</p> <p>Background</p> <p>In this study we used radiotelemetry to measure hemodynamic variables and locomotor activity in conscious unrestrained male Protease-Activated Receptor 2 (PAR-2) knockout mice in order to provide a detailed assessment of their blood pressure phenotype. In addition we tested for an influence of PAR-2 on salt-sensitivity (8% versus 0.5% NaCl diet, 2.5 weeks) and angiotensin II-induced hypertension (1 μg Ile⁵-angiotensin II/kg/min versus 0.25 μl/h saline, 2 weeks).</p> <p>Results</p> <p>Systolic arterial pressures of PAR-2 -/- (129 ± 1 mmHg, n = 21, P < 0.05) were statistically higher than those of C57BL/6J (124 ± 1 mmHg, n = 33) throughout the 24 h period under baseline conditions. Pulse pressures in PAR-2 -/- were also significantly elevated (33 ± 1 mmHg versus 30 ± 1 mmHg, P < 0.05), whereas diastolic arterial pressures were not. Heart rates in PAR-2 -/- were not significantly different than controls, with the exception that heart rate of PAR-2 -/- was 23 beats per min higher than controls (<it>P </it>< 0.001) during periods of nocturnal activity. The diurnal pattern and intensity of locomotor activity were not found to differ between strains. A high salt diet led to increased blood pressures, decreased heart rates, increased time spent active and decreased intensity levels of locomotor activity. Salt-induced changes in systolic and pulse pressures in PAR-2 -/- were less than in C57B/6J. Angiotensin II treatment increased pressures, decreased heart rates, decreased time spent active and decreased intensity levels of activity of PAR-2 -/-, all to the same extent as C57BL/6J. A trend of lower blood pressures during the middle period of angiotensin II treatment period was observed in individual PAR-2 -/-.</p> <p>Conclusion</p> <p>The data indicated gene knockout of PAR-2 was associated with a modest change in blood pressure phenotype. PAR-2 -/- mice exhibited moderate elevation of systolic arterial and pulse pressures, yet no increased diastolic arterial pressure, no increased blood pressure responses to high salt diet and a subtle difference in the time course of the blood pressure responses to angiotensin II infusion.</p

A multi-component model of the dynamics of salt-induced hypertension in Dahl-S rats

Background. In humans, salt intake has been suggested to influence blood pressure (BP) on a wide range of time scales ranging from several hours or days to many months or years. Detailed time course data collected in the Dahl salt-sensitive rat strain suggest that the development of salt-induced hypertension may consist of several distinct phases or components that differ in their timing and reversibility. To better understand these components, the present study sought to model the dynamics of salt-induced hypertension in the Dahl salt sensitive (Dahl-S) rat using 3 sets of time course data. Results. The first component of the model ("Acute-Reversible") consisted of a linear transfer function to account for the rapid and reversible effects of salt on BP (ie. acute salt sensitivity, corresponding with a depressed slope of the chronic pressure natriuresis relationship). For the second component ("Progressive-Irreversible"), an integrator function was used to represent the relatively slow, progressive, and irreversible effect of high salt intake on BP (corresponding with a progressive salt-induced shift of the chronic pressure natriuresis relationship to higher BP levels). A third component ("Progressive-Reversible") consisted of an effect of high salt intake to progressively increase the acute salt-sensitivity of BP (ie. reduce the slope of the chronic pressure natriuresis relationship), amounting to a slow and progressive, yet reversible, component of salt-induced hypertension. While the 3 component model was limited in its ability to follow the BP response to rapid and/or brief transitions in salt intake, it was able to accurately follow the slower steady state components of salt-induced BP changes. This model exhibited low values of mean absolute error (1.92 0.23, 2.13 0.37, 2.03 0.3 mmHg for data sets 1 - 3), and its overall performance was significantly improved over that of an initial model having only 2 components. The 3 component model performed well when applied to data from hybrids of Dahl salt sensitive and Dahl salt resistant rats in which salt sensitivity varied greatly in its extent and character (mean absolute error = 1.11 0.08 mmHg). Conclusion. Our results suggest that the slow process of development of salt-induced hypertension in Dahl-S rats over a period of many weeks can be well represented by a combination of three components that differ in their timing, reversibility, and their associated effect on the chronic pressure natriuresis relationship. These components are important to distinguish since each may represent a unique set of underlying mechanisms of salt-induced hypertension