Assessing Growth and Water Productivity for Drip-Irrigated Maize under High Plant Density in Arid to Semi-Humid Climates

Determining the water productivity of maize is of great significance for ensuring food security and coping with climate change. In 2018 and 2019, we conducted field trials in arid areas (Changji), semi-arid areas (Qitai) and semi-humid areas (Xinyuan). The hybrid XY335 was selected for the experiment, the planting density was 12.0 × 104 plants ha−1, and five irrigation amounts were set. The results showed that yield, biomass, and transpiration varied substantially and significantly between experimental sites, irrigation and years. Likewise, water use efficiency (WUE) for both biomass (WUEB) and yield (WUEY) were affected by these factors, including a significant interaction. Normalized water productivity (WP*) of maize increased significantly with an increase in irrigation. The WP* for film mulched drip irrigation maize was 37.81 g m−2 d−1; it was varied significantly between sites and irrigation or their interaction. We conclude that WP* differs from the conventional parameter for water productivity but is a useful parameter for assessing the attainable rate of film-mulched drip irrigation maize growth and yield in arid areas, semi-arid areas and semi-humid areas. The parametric AquaCrop model was not accurate in simulating soil water under film mulching. However, it was suitable for the prediction of canopy coverage (CC) for most irrigation treatments.

Lantana camara: Poisonous Species and a Potential Browse Species for Goats in Southern Africa—A Review

Among the possible impacts of plant invaders on South African biodiversity, water supplies, and rangeland production, Lantana camara is ranked the highest in terms of its environmental impact. Globally, L. camara is regarded as one of the most ecologically and economically destructive invasive alien plants. The spread of L. camara affects the environment and threatens livestock productivity due to its toxicity to animals (especial cattle and sheep) in most semi-arid areas of South Africa. Lantana camara is known to have high concentrations of nutrients that are beneficial to livestock, but most previous research has concentrated on its toxicity. To enrich our knowledge on its nutritive value, further research has to evaluate its dietary impact on the growth and health of different ruminant livestock species, particularly goats. This review evaluates L. camara as a potential browse species for goats in southern Africa, and its adverse effects on goats and other ruminant livestock are also presented. The review describes L. camara and its distribution globally, its poisonous effect to livestock, and potential use as an alternative forage to browsing animals such as goats, which have proved resistant to its harmful traits. The high crude protein content, low fibre and adequate macro-minerals for small ruminants makes L. camara a good ruminant protein supplement in semi-arid areas. In addition to other biological control strategies, the prospects of using goats as a biological management tool is discussed. The research will contribute to the understanding of the control measures of L. camara while improving the productivity of small stock, especially goats. This means that a balanced understanding of its nutritional value as a source of protein and its negative impact on the environment should be considered in developing mitigation strategies to arrest its spread. We, therefore, recommend the use of goats in the control of L. camara; however, further studies are needed to limit its toxic effects, and thus improve its value.

A scheme to detect sand/dust weather applying meteorological radars

Sandy dust weather occur frequently in arid and semi-arid areas. It is important to actually detect the sandy dust grain concentration or the visibility of the sandy dust weather for weather forecasting. In this paper, based on numerical calculation of the effective detection distance of different radar detecting the sandy-dust weather with different strength, a scheme to detect sand/dust weather applying existed meteorological radar stations is proposed in this paper. The scheme can be efficient to detect sandy dust weather, for it makes a good supplement to the current deficiencies in detecting sandy dust weather and it’s a cost-saving detection way by using the existed meteorological radars. In addition, the effect of charges carried by sand/dust grains and the relative humidity on the effective detection distance of radar is also investigated, and it shows that these effects will not change the proposed scheme. It will be promising to detect the sandy dust weather in the way of disastrous weather precaution by using this scheme.

Greywater as an Alternative Solution for a Sustainable Management of Water Resources—A Review

In this paper, a comprehensive review on greywater is presented. Emphasis is given to the techniques used to treat and recover greywater, and special emphasis is placed on the risk of the existence of the novel coronavirus “SARS-CoV-2” in greywater and the possibility of its spread via the reuse of this water. In general, greywater is considered wastewater collected from domestic sources, with the exclusion of toilet water (which is considered as blackwater). Greywater represents 50 to 80% of the total volume of wastewater all over the world. This review provides various aspects related to greywater, such as origins, characteristics, and existing guidelines for greywater proper treatment and reuse. Several approaches and techniques have been developed to study the performance of different greywater treatment systems. These methods are critically discussed in this article. In the context of sustainable development, water management, and taking into account the scarcity of water resources, particularly in arid and semi-arid areas, the use of treated greywater is one of the alternatives methods that can reduce the burden of withdrawals from the resource. In addition, some successful examples of greywater valuation experiences in Tunisia were examined.

An Experimental Study on the Effect of Micro-Metakaolin on the Strength and Swelling Characteristics of Expansive Soils

Expansive soils are found in many parts of the world, especially in arid areas and dry weather regions. Urbanization and development of new cities around the world resulted in construction in areas of challenging subsurface soil conditions. For example, in the Middle East, the Government of Egypt is building several new cities to accommodate the continuous increase in the country’s population. Most of these new cities are located in areas underlain by expansive soils. In this study, a series of laboratory tests were carried out to investigate the effect of introducing micro-metakaolin into the matrix of an expansive soil to improve the swelling potential as a new stabilizing material. Test results showed that micro-metakaolin can considerably decrease the free swell index of the soil by 37% and 54% at micro-metakaolin content of 15% and 25%, respectively. In addition, the shear strength of the soil was found to also increase as a result of the introduction of the micro-metakaolin material. Adding 25% micro-metakaolin content reduced the swelling pressure of the soil by about 33%. The results suggest that the proposed method is efficient in stabilizing and improving the properties of expansive soils found in arid areas. This is important to control excessive swelling and prevent possible damage to the supported structures.

Spatiotemporal Variability of Intensity–Duration–Frequency (IDF) Curves in Arid Areas: Wadi AL-Lith, Saudi Arabia as a Case Study

In arid areas, flashflood water management is a major concern due to arid climate ambiguity. The examining and derivation of intensity–duration–frequency (IDF) curves in an urban arid area under a variety of terrain patterns and climatic changes is anticipated. Several flood events have been reported in the Al-Lith region of western Saudi Arabia that took away many lives and caused disruption in services and trade. To find and examine the extremities and IDF curves, daily rainfall data from 1966 to 2018 is used. The IDF curves are created for a variety of return periods and climate scenarios in three terrain variabilities. This research examines various distributions to estimate the maximum rainfall for several metrological stations with varying return periods and terrain conditions. Three main zones are identified based on ground elevation variability and IDF distributions from upstream in the eastern mountainous area to downstream in the western coastal area. These IDF curves can be used to identify vulnerable hotspot areas in arid areas such as the Wadi AL-Lith, and flood mitigation steps can be suggested to minimize flood risk.