Day 1 :
University of Florida, USA
Time : 10:05-10:50
Kelly T Morgan is a Professor of Crop Irrigation and Nutrient Management at the University of Florida. He has received his graduate degrees from the University of Florida in Soil and Water Science and Agricultural Engineering Departments. He has worked in University of Florida for 26 years specializing in improving water and nutrient use efficiency in the sandy soils of central and south Florida. His studies to assess nutrient application rates and irrigation management to increase nutrient use efficiency and minimize nutrient loss to the environment. He has published over 75 peer reviewed journal papers, 10 book chapters, and nearly 200 other publications.
Due to production declining and negative economic effects, there is an urgent need for strategies that reduce the impact of Huanglongbing (HLB) on citrus (Citrus x sinensis (L.) Osbeck). The objective of this study was to evaluate the impact of different irrigation schedules on soil volumetric water content (θv) and water uptake characteristics of citrus trees affected by HLB in central and southwest Florida. The study was conducted during two years on five-year-old sweet orange (Citrus x sinensis (L.) Osbeck) trees located in three commercial groves at Arcadia, Avon Park, and Immokalee, Florida. Three irrigation treatments included University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) recommendations, daily irrigation, and a schedule intermediate to the selected treatments and provided similar volumes of water per week based on ETo. Sap flow (SF), leaf area, leaf area index, and stem water potential (Ψ) were determined at selected intervals. Also, θv was measured using capacitance soil moisture sensors at incremental soil depths of 0-15, 15-30, and 30-45 cm. Significant differences (α=0.05) were found in average SF, leaf area index, Ψ, and θv measurements among treatments. Diurnal SF value under daily irrigation treatment increased by 91%, 51%, and 105% and θv under daily treatment increased by 39%, 13%, and 57% compared to UF/IFAS irrigation treatment in Arcadia, Avon Park and Immokalee, respectively. Results indicate that, daily irrigation improves trees water dynamics and greater mean soil water content than UF/IFAS or intermediate treatments and reduce trees stress with the same volume of irrigation water.
NRU MGSU, Russia
Time : 11:15-11:45
Vladimir I Andreev is a Head of Department Strength of materials at National University Moscow State University of Civil Engineering. He is also an Professor, Doctor of Technical Sciences, full member of the Russian Academy of Architecture and Construction Sciences (RAASN), a member of UMO universities of Russia for education in the field of construction. He is an Honored Worker of Higher School, member of the Russian National Committee on Theoretical and Applied Mechanics and Honorary professor at the Warsaw University, honorary builder of Russia.
The rupture of water and sewer pipes leads to numerous accidents (subsidence, swelling, etc.). This is especially characteristic for clay, loess, peat and other soils. We consider the stress state of clay array at different models on fluid propagation from a fracture site. Accordingly, the problems are solved in cylindrical and spherical coordinates. The problem is solved by the methods of stationary and non-stationary moisture elasticity. The feature of the calculation is the accounting of the inhomogeneity of the clay during moistening. Figure 1 shows the dependence of the clay deformation modulus on moisture. Depending on the depth of the pipe where the fracture occurred, the ground pressure can be considered axisymmetric (large depth) and non-axisymmetric (small depth). Accordingly, one-dimensional and two-dimensional problems of moisture elasticity are considered. Analytical and numerical-analytical solutions are obtained. An analysis is made of the convergence of the Fourier series as a function of the number of terms in the series. As a result of calculations, it was found that taking into account the inhomogeneity caused by the change in the deformation properties of bodies leads to a significant change in the stress state of bodies compared to the calculation of homogeneous bodies. In clay soils, against the background of a marked reduction in the peaks of compressive stresses, the most dangerous maximum tensile stresses for a cylindrical model increase by 53%, and for a spherical stress increase by 38%.