Test of a microlysimeter for measurement of soil evaporation

A quantificação da evaporação do solo é requerida em estudos de balanço hídrico de culturas e em aplicações que visam a aumentar a eficiência do uso da água pelos cultivos. O objetivo deste trabalho foi testar um modelo de microlisímetro (ML) para medir a evaporação do solo em condições irrigada e não irrigada. Os MLs foram construídos utilizando tubos de PVC rígido, medindo 100 mm de diâmetro interno, 150 mm de profundidade e 2,5 mm de espessura da parede. Quatro MLs foram assentados sobre a superfície de dois lisímetros de pesagem de alta precisão conduzidos com solo nu, previamente instalados no Iapar, em Londrina-PR. Os lisímetros tinham dimensões de 1,4 m de largura, 1,9 m de comprimento e 1,3 m de profundidade, e estavam sendo conduzidos com e sem irrigação. A evaporação medida nos MLs (E ML) foi comparada com a medida nos lisímetros (E L), durante quatro períodos do ano. As diferenças entre E ML e E L foram mínimas para condições de baixa e elevada demanda atmosférica, e também para condições de solo irrigado ou não irrigado, indicado que o modelo de ML testado neste trabalho é adequado para medir a evaporação do solo.Quantifying soil evaporation is required on studies of soil water balance and applications aiming to improve water use efficiency by crops. The performance of a microlysimeter (ML) to measure soil evaporation under irrigation and non-irrigation was evaluated. The MLs were constructed using PVC tubes, with dimensions of 100 mm inner diameter, 150 mm depth and 2.5 mm wall thickness. Four MLs were uniformly distributed on the soil surface of two weighing lysimeters conducted under bare soil, previously installed at Iapar, in Londrina, PR, Brazil. The lysimeters had 1.4 m width, 1.9 m length and 1.3 m depth and were conducted with and without irrigation. Evaporation measurements by MLs (E ML) were compared with measurements by lysimeters (E L) during four different periods in the year. Differences between E ML and E L were small either for low or high atmospheric demand and also for either irrigated or non-irrigated conditions, which indicates that the ML tested here is suitable for measurement of soil evaporation

SOIL COVER IS STRATEGIC TO REMEDY EROSION IN SANDY SOILS

ABSTRACT Sandy-textured soils are naturally more vulnerable to the erosion process and their exploitation, although possible, is often performed inappropriately, favoring its degradation. In this context, this study aimed to classify the rainfall erosivity in a region of sandy soils to identify critical situations of soil and water loss and also correlate it with rainfall data to assess whether there is temporal dependence of this variable using geostatistical techniques. The potential for alternative and sustainable production systems to be used in regions with sandy soils was also analyzed. Historical data of precipitation in the study region were analyzed to determine the average monthly and annual erosivity indices, which were classified and its temporal dependence was assessed by applying geostatistics. NDVI data from satellite images were used to investigate the soil cover pattern in different production systems. Geostatistics was adequate for the analysis of rainfall erosivity, which showed moderate to strong temporal dependence. It was classified between strong and very strong and was highly dependent on precipitation, with events of higher erosion potential between October and March in the studied region. The vicious circle of degradation of sandy soils, such as those of the Bolsão region of Mato Grosso do Sul, Brazil, can be modified by adopting alternative and sustainable production systems that value the maximization of soil cover

Crescimento e qualidade de mudas de pinhão-manso produzidas em ambiente protegido Growth and quality of physic nut seedlings produced in greenhouse

Devido ao recente Programa de Produção de Biocombustíveis do Brasil, o interesse comercial tem crescido em relação à produção de pinhão-manso (Jatropha curcas L.). Informações sobre esta cultura ainda são escassas, o que remete a necessidade de mais pesquisas que possam estabelecer condições de adaptabilidade desta cultura em diferentes condições. Neste contexto, realizou-se um experimento para estudar o crescimento e a qualidade das mudas de pinhão-manso, produzidas em ambiente protegido; as mudas foram monitoradas até o momento de serem transplantadas para o campo. Foi analisada a influência dos tipos e volumes de recipientes, juntamente com diferentes substratos e formas de adubação; o consumo de água também foi analisado durante o experimento. De acordo com os resultados, as melhores taxas de crescimento e qualidade de mudas até a condição de transplantio, foram obtidas com a combinação do substrato comercial, maior tubete e adubo de liberação lenta.<br>There has been an increasing interest in the commercial production of physic nut (Jatropha curcas L.) due to the recent Brazilian Program of Biofuel Production. Information on this crop is still scarce and more research is necessary to set the grounds of crop adaptability in different local conditions. An experiment was set up on this issue under greenhouse environment. Growth and quality of physic nut seedlings was monitored up to transplanting time. The influence of types and volumes of seedling containers was analysed along with different substrates and fertilization strategies. The water use was also detailed in the trial. Results showed the best achievements of growth rate and seedling quality, at appropriate transplanting time, were reached from the combination of the commercial substrate, largest containers and fertilizers of slow nutrient liberation