A large reservoir of bioavailable nitrogen (up to approximately 10(4) kilograms of nitrogen per hectare, as nitrate) has been previously overlooked in studies of global nitrogen distribution. The reservoir has been accumulating in subsoil zones of arid regions throughout the Holocene. Consideration of the subsoil reservoir raises estimates of vadose-zone nitrogen inventories by 14 to 71% for wa...

this paper reports the results of using three empirical methods (makkink, priestley-taylor and hargreaves) for estimating the reference evapotranspiration (et0) in the semi-arid region of tensift al haouz, marrakech (center of morocco). the penman-monteith equation, standardized by the food and agriculture organization (fao-pm), is used to evaluate the three empirical methods. the obtained et0 ...

crops growing in salt-affected soils may suffer from physiological drought stress, ion toxicity, and mineral deficiency. a pot study was conducted in 2004-2005 in the aghala area (northern iran) to study the effect of different salinity levels, i.e. ece= 3 (control), 8, 12 and 16 ds m-1 on wheat grain, yield components and leaf ion uptake of four iranian wheat genotypes, i.e. kouhdasht, atrak, ...

drought detecting is a necessary aspect of drought risk management. it is generally performed usingdifferent drought indices that are effectively continuous functions of rainfall and other hydro- meteorologicalvariables. a number of drought indices have been introduced and used in various countries to date. in thecurrent research, four meteorological drought indices including the standardized p...

one of the ordinary methods to protect, rehabilitate, and enhance an ecosystemfunction in arid and semi-arid areas of the world is sand dune stabilization using biologicalpractices. plantation of species on the soil plays a great role in sustainable management ofthe ecosystem. this research studies the effects of cultivation of haloxylon ammodendronand atriplex canescens on physical-chemical ch...

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Conserving water resources is a current challenge that will become increasingly urgent in future due to climate change. The arid and semi-arid areas of the globe are expected be particularly affected by changes availability. Consequently, advances ecohydrology sciences, i.e., interplay between ecological hydrological processes, necessary enhance understanding critical zone, optimize resources’ ...

isfahan province is located in the center of iran and has arid and semi-arid climate. in recent years, water shortage has increased in this region and has affected crop production. wheat is one of the most important crops of the province. in the present research, an index (dei) has been developed for drought evaluation using long term climatic data through application of principle components an...