Hassan El-Ramady

Drought risk assessment using remote sensing and GIS techniques

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.

Selenium and nano-selenium in plant nutrition

Abstract Selenium (Se) is a naturally occurring metalloid element which occurs nearly in all environments. Se is considered as a finite and non-renewable resource on the Earth. The common sources of Se in earth’s crust occur in association with sulfide minerals such as metal selenide, whereas it is rarely found in elemental form (Se0). While there is no evidence of Se need for higher plants, several reports show that when Se added at low concentrations, Se exerts beneficial effects on plant growth. Se may act as quasi-essential micronutrient through altering different physiological and biochemical traits. Thus, plants vary considerably in their physiological and biochemical response to Se. This review focusses on the physiological importance of Se forms as well as different Se fertilizers for higher plants, especially plant growth, uptake, transport, and metabolism.

Overview of Selenium Deficiency and Toxicity Worldwide: Affected Areas, Selenium-Related Health Issues, and Case Studies

Selenium (Se) is an essential micronutrient for human and animal healthy due to its capabilities to support antioxidant defence systems. However, problems related to the deficiency of Se are emerging issue for human health worldwide and plant species differ considerably in their susceptibility to high concentrations of Se, and certain plant species can be able to accumulate Se to astonishingly high concentrations. Many factors can affect the content of Se in different foods, including different uptake rate by plants, which can be related to plant type, soil, pH, microbial activity, rainfall and a number of other biogeochemical parameters. Humans Se intake and Se status in the population depends firstly on Se concentrations in soils, and hence the Se concentrations in the harvested edible plants in these soils. Thus, this chapter aims to compile some information about research work on essentiality of Se for humans and other mammals, and the need for a sufficient daily Se intake.

Selenium in Agriculture: Water, Air, Soil, Plants, Food, Animals and Nanoselenium

Selenium (Se) is an example of an essential element becoming more and more insufficient in food crops as a result of intensive plant production in many countries. Se is an essential biological trace element. It is an essential constituent of several enzymes in which it is present in the form of the unusual amino acid selenocysteine (SeCys). Se was first recognized as an essential nutrient in the late 1950s when it was found to replace vitamin E in the diets of rats and chicks for the prevention of vascular, muscular and/or hepatic lesions. Until that time, Se had been thought of only as a toxicant, being associated with “alkali disease” in grazing livestock in the northern Great Plains of the United States. Since that time, Se has become the subject of investigations in many parts of the world. Se enters soils primarily as a result of the weathering of Se-containing rocks, although volcanic activity, dusts such as in the vicinity of coal burning, Se-containing fertilizers, and some waters can also be sources. Se cycles through the food system, being removed from soils by plants and soil microorganisms, which can take up the element into their tissue proteins and metabolize some of it to volatile forms e.g., dimethylselenide. The latter enter the atmosphere to be brought down with precipitation and airborne particulates. This chapter reviews the present knowledge of the Se in agroecosystem. The occurrence of selenium in the environment from soil to food systems is discussed. The most promising and important nanotechnology applications in agriculture; and nano-selenium particles production, agricultural nanotechnology and its use in sustainable development will also be highlighted.

Nanoparticles, Soils, Plants and Sustainable Agriculture

Humanity faces major challenges involving energy, water, food, environment, poverty, diseases, education, democracy and population. Green nanotechnology could be a solution for providing sustainable energy, clean water and a better environment. Various nanomaterials can sustain the agricultural sectors. Here we review the applications of nanoparticles for soil security and plant nutrition.

Integrated Nutrient Management and Postharvest of Crops

Rational pursuit of sustainability is only possible if society could agree upon what sustainability is, or more exactly, if mankind knows what we want to sustain. Policy reforms are a requirement for achieving sustainability. Much can be achieved by promoting polices that help better resource allocation and at the same preserve the natural ecosystem. In addition, conservation incentives are needed through functioning of the marketplace, along with an assessment of alternative mechanisms to control externalities. Soils represent dynamic ecosystems, making it appropriate to think about them in terms such as health, vitality and biological productivity. Soils are the resources that provide humans with more than 90 % of all the food we eat. Our challenge is to manage soils in a sustainable fashion so that they will provide for human needs in the future. However, the measurement of soil processes and of the soil properties linked to these also depend on the use and location of the soil. When evaluating soil quality, it is therefore common to explore a range of soil physical, chemical, and biological properties.

Exogenous nanosilica improves germination and growth of cucumber by maintaining K+/Na+ ratio under elevated Na+ stress

The current work was aimed to elucidate the role of engineered nanosilica (SiNPs) particles to mitigate the damaging impacts of Na+-derived salinity on cucumber (Cucumis sativus) Beit Alpha variety by conducting in vitro experiments applying various Na+ concentrations i.e. 0, 1000, 2000, 3000, 4000 and 5000 mg L-1. By treating seeds and seedlings, respectively, of cucumber with SiNPs (0, 100, 200 and 300 ppm) and subsequent determination some germination and vegetative parameters as well as chemical analysis of seedlings, we verified that SiNPs succeeded to alleviate the detrimental effects of high Na+ salinity by increasing germination parameters and vegetative growth of cucumber seedlings. Even as little as 100 ppm of N-Si results in considerable improvement of seed germination and seedlings growth of cucumber compared to the control, while 200 ppm was optimal among the doses tested. At 5000 mg Na+ L-1, applying SiNPs with 200 ppm increased final germination percentage by 101% over control, vigor index by 101%, germination rate index by 116%, germination index by 110%, fresh mass by 13%, K+/Na+ ratio by 77%, shoot dry mass by 384%, root dry mass by 304% and plant height by 70%. The results mentioned in this paper obviously outline the large practical relevance of SiNPs and imply that applying of SiNPs for cucumber seeds and seedlings under high Na+-derived salinity enhances germination and growth as a result for decreasing Na+ uptake and sequentially improves high K+/Na+ ratio.

The Rhizosphere and Plant Nutrition Under Climate Change

The plant root–soil interfaces could be considered the rhizosphere area, which is the most important active zone in the soils for different microbial activities, biodegradation of pollutants and plant nutrition. Polluted soils are characterized by low organic matter content, limiting their microbial activity, nutrient availability and degradation of pollutants. Soil phyto- and/or bioremediation is mainly based on the use of plant roots and their associated soil microorganisms, whereas conventional approaches are based on physico-chemical methods in soil remediation. Plant root exudates are the most important compounds in the rhizosphere, which play a crucial role in the interactions between plant roots and soil microbes. It is worthy to mention that several plant species and soil microbes have been used in soil remediation for different pollutants. The role of rhizosphere and its significance in plant nutrition are mainly controlled by the change in climatic attributes including temperature, moisture content, precipitation, etc. Therefore, global warming and climate changes do have a great and serious effect on the agricultural production through their effects on the rhizosphere and in turn plant nutrition. Hence, the aim of this review is to evaluate the significance of rhizosphere in plant nutrition under the changing climate. Soil biological activity and its security will be also highlighted.

Future Soil Issues

Soils are among the key resources of sustainable development in Egypt. There would be no development, in any nation, without policies and implementation for soil protection, conservation, and sustainability. This is due to the role soils play in almost all fields, including agriculture and its subsectors (farming of animals and plants to produce food, feed, fiber, fuel, etc.), as well as the industrial sector. Egypt faces, currently, great and serious challenges related to the changes in land use, new challenges for soil sciences scientists. Other important future soil issues include the role of soils in global climate changes mitigation/adaptation, establishment of soil protection law, and enforcing it. To solve emerging soil-related problems in Egypt, potential contributions from soil scientists, policymakers, and society are expected. Therefore, this chapter is an attempt to focus on emerging concern on soil and to suggest suitable solutions under the Egyptian conditions.

Soils and Humans

Soil has a great and holy position worldwide. This position has been acquired from the importance of soil in saving food, feed, fuel, and fibre for animals and humans. Egypt was and still one of the most important countries, which soils played a crucial role in the Egyptian civilization. Therefore, very strong link between soils and humans has been reported based on the great roles of soils in plant and human nutrition. On the other hand, there are several anthropogenic activities, which cause many problems for soils such as pollution, degradation, and erosion. There are direct and/or indirect effects of soils on human health as well as plants. Therefore, this chapter is an attempt to emphasize the great roles of soils in plant and human health as well as the security of soils under pollution conditions.