In this study, leaching experiments were carried out by both continuous and alternate ponding methodsin the south of Khouzestan province. In equal applied water leaching, alternate ponding leachingmodel had a better performance than continuous ponding method in desalinization and dealkalization.In term of alternate method,there was not ayn difference between 5 and 8 day periods in one-meterdept...

The study was conducted at the Bangladesh Rice Research Institute Regional Station, Comilla, during three rice growing seasons. The experiment consists of six weeding treatments with three replications. The objective of the experiment was to determine an economic weeding method as well as to improve water management practices of paddy rice. The study indicates that the continuous ponding (100±1...

The recent shift from transplanted to wet seeded rice (Oryza sativa L.) in South East Asia has resulted in major weed problems which require more labour and energy for their control. Field experiments were conducted during 1994±1996 on a Chromic Vertisol in central Luzon, the Philippines, to study the effect of water, tillage and herbicide levels on total water use, weed growth and yield of wet...

In regions like south of “ khouzestan” that water table are high, under the effect of water rise moving through capillary fringe and its vaporize,  the salts move to soil surface and cause salin or salin and sodic soils. Leaching assign as one of those adjustment soils methods. In order to investigate the leaching process and draw the curves of desalinization and dealkalization in region of Dar...

Northern California supports eight endemic species of large branchiopods (Crustacea: Anostraca, Notostraca, and Conchostraca), three of which are listed as endangered and one as threatened under the federal Endangered Species Act. Published information on the geographic distribution of these endemics from a biological perspective is scant. This study was initiated to gain a better understanding...

Surface melt ponds form intermittently on several Antarctic ice shelves. Although implicated in ice-shelf break up, the consequences of such ponding for ice formation and ice-shelf structure have not been evaluated. Here we report the discovery of a massive subsurface ice layer, at least 16 km across, several kilometres long and tens of metres deep, located in an area of intense melting and int...

Over three million hectares of salt-affected soils characterized with high salinity and sodicity caused serious land degradation in Songnen Plain, northeast China. Soil salinity–sodicity heterogeneous distribution under microtopography is usually influenced by several environmental factors. The side direction movement of soil water driven by water from depression is the key factor that aggravat...

The objectives of this study were to investigate the degree of spatial variability and variance structure of salinization parameters using classical and geostatistical method in Songnen Plain of China, which is one of largest saline-sodic areas in the World, and to analyze the relationship between salinization parameters, including soil salinity content (SC), electrical conductivity (EC), sodiu...

A recent approach to solve Richards' equation is further improved. This approach brings understanding into the physical processes of in®ltration and ponding. In particular we apply it to analyze the standard hydrologic tool of Time Compression Approximation (TCA). We also suggest that the new approach provides a more reliable alternative to TCA, e.g. for predicting ponding time. Ó 1999 Elsevier...