Trees in urban areas increase the liveability of towns and cities but street tree growth can be constrained by the limited soil volume available for root growth and by reduced water and nutrient availability under impervious urban surfaces. An approach to improve the growth and health of street trees is the installation of permeable pavements. This study assessed whether permeable pavements with varying depths (0, 100 or 300 mm) of an underlying base layer affected soil moisture, soil temperature, tree growth and leaf nutrient status when broad-leaf paperbark (Melaleuca quinquenervia) trees were planted in two soil types, sand and clay. Permeable pavements increased moisture levels in drier sandy soil but decreased moisture levels in wetter clay soil after rainfall, with the stabilising effect of the permeable pavement on moisture levels being related to the depth of the underlying base layer. Permeable pavements and their base layers also had moderating effects on soil temperature. Permeable pavement with a deep drainage layer (300 mm) increased trunk diameter growth by 55%, although growth was only increased when trees were planted in clay. Permeable pavements with a shallower drainage layer (0 or 100 mm) did not affect tree growth compared with trees in control asphalt pavements. However, permeable pavements without a drainage layer reduced tree height growth in clay soil by 37 to 38% compared with pavements with a 100 mm or 300 mm drainage layer. In contrast, permeable pavements without a drainage layer increased trunk diameter growth in sandy soil by 65% compared with permeable pavement with a 100 mm drainage layer. Leaf nutrient concentrations were often unaffected by pavement design but differences in growth between treatments were associated with differences in the concentrations of some nutrients including K, Mg and S. This study demonstrated that inclusion of underlying base layers is important for tree growth when permeable pavements are installed on poorly-draining soils. Inclusion of a base layer may not be optimal for tree growth when permeable pavements are installed over freely-draining soils. (C) 2014 Elsevier GmbH. All rights reserved.

Water-repellent (non-wetting') soils are a major constraint to agricultural production in southern and south-west Australia, affecting >10Mha of arable sandy soils. The major symptom is dry patches of surface soil, even after substantial rainfall, directly affecting agricultural production through uneven crop and pasture germination, and reduced nutrient availability. In addition, staggered weed germination impedes effective weed control, and delayed crop and pasture germination increases the risk of wind erosion. Water repellency is caused by waxy organic compounds derived from the breakdown of organic matter mostly of plant origin. It is more prevalent in soils with a sandy surface texture; their low particle surface area:volume ratio means that a smaller amount of waxy organic compounds can effectively cover a greater proportion of the particle surface area than in a fine-textured soil. Water repellency commonly occurs in sandy duplex soils (Sodosols and Chromosols) and deep sandy soils (Tenosols) but can also occur in Calcarosols, Kurosols and Podosols that have a sandy surface texture. Severity of water repellency has intensified in some areas with the adoption of no-till farming, which leads to the accumulation of soil organic matter (and hence waxy compounds) at the soil surface. Growers have also noticed worsening repellency after dry' or early sowing when break-of-season rains have been unreliable. Management strategies for water repellency fall into three categories: (i) amelioration, the properties of surface soils are changed; (ii) mitigation, water repellency is managed to allow crop and pasture production; (iii) avoidance, severely affected or poorly producing areas are removed from annual production and sown to perennial forage. Amelioration techniques include claying, deep cultivation with tools such as rotary spaders, or one-off soil inversion with mouldboard ploughs. These techniques can be expensive, but produce substantial, long-lasting benefits. However, they carry significant environmental risks if not adopted correctly. Mitigation strategies include furrow-seeding, application of wetting agents (surfactants), no-till with stubble retention, on-row seeding, and stimulating natural microbial degradation of waxy compounds. These are much cheaper than amelioration strategies, but have smaller and sometimes inconsistent impacts on crop production. For any given farm, economic analysis suggests that small patches of water repellency might best be ameliorated, but large areas should be treated initially with mitigation strategies. Further research is required to determine the long-term impacts of cultivation treatments, seeding systems and chemical and biological amendments on the expression and management of water repellency in an agricultural context.

Science plays an important role in institutional change, but the types and mechanisms of science-driven institutional change have received little attention in the mainstream discourse concerning institutions, institutional change and social governance. Comparing 25 cases using data from surveys, interviews, observations and a meta-analysis of archives regarding desertification control in northern China, this study found that, although science influenced the results of desertification control through influencing institutional change, its influence was also constrained by the types and working principles of science-driven institutional change. When analyzing the application of different methods of desertification control, the type of biological control that dominates the interaction (biological-control-dominant interaction) may be that of science-driven intuitional change variables with the highest desertification control performance, whereas for the participants in desertification control the type of high participation and multiple interactions may be the variable with the greatest influence. This study also proposes nine principles for effective science-driven institutional change that address collaborative, effective and sustainable applications and extensions of advanced scientific methods, effective collaboration among various social actors and organizations, and localized, collaborative and nested laws, regulations and rules regarding desertification control. Stronger rules result in more effective science-driven institutional changes. These findings provide an outline for reforming the models of science-driven institutional change and implementing future science and technology policies for desertification control and other types of ecological and environmental governance. This study also provides a theoretical and empirical foundation for further research concerning science-driven institutional change. Copyright (c) 2015 John Wiley & Sons, Ltd and ERP Environment

A typical desert shrub species, Hedysarum scoparium (C-3 plant) with green rachis, was analyzed on phosphoenolpyruvate carboxylase (PEPC) for considering increasing soil water stress as a probable driving factor to affect assimilation of plant in arid areas. The samples were planted in cultivation plots at depths of 1.4 m, 2.4 m and 3.4 m sandy soil respectively in this study. Water was periodically supplemented at the bottom of each cultivation plot to simulate soil water stress. The studies of activities of PEPC in two assimilating organs indicated that different photosynthetic organs possess different traits of CO2 fixation. The results showed that PEPC presented both in leaflet and rachis of H. scoparium, and enhanced largely with the increasing soil depth. The result suggest that there is a adaptation strategy for desert species with green rachis expanding C-4 photosynthesis in H. scoparium under severe soil water deficit.

this paper, Pishan county sewage treatment and the desert greening have been studied. We have analyzed the advantages and disadvantages of the wetland mechanism and its purification in the sewage treatment in Pishan county as the test results of reused sewage for greening the desert. It has proved that the constructed wetland sewage can be made to receive significant environmental, economic and social benefits. Deeply studying has demonstrated that constructed wetland mechanism in arid areas will change the environment of Xinjiang and that of the country.

Saudi Arabia is witnessing unparalleled development for all types of construction, especially in eastern Saudi Arabia where the major oil and petrochemical industries are located. In this region, major projects are often located on sandy soils and it is difficult to assess the properties of sands using conventional methods. In this investigation, a laboratory program was conducted using the dynamic cone penetration test (DCPT) on sand samples with different relative densities (40%, 60% and 90%) that were compacted in a large scale mold (1600 mm diameter and 1500 mm height). The placement of sand was achieved through the pluviation and vibration techniques. Results of investigation indicated that the increase in the dry density was associated with a decrease in the dynamic cone penetration index (DCPI). Further, it was noted that the shear strength has a significant effect on the dynamic cone penetration test results. In summary, results of this investigation indicate that DCPT is an effective and reliable tool in the assessment of the properties of sand backfills.

Effects of using different year of humic acid on millet growth and water and fertilizer use efficiency was studied in a field experiment in a semi-arid and arid region in 2011-2014. Four-year results showed that after using humic acid, the soil moisture content was increased by 0.20%-40.41% over that of CK, and it mainly affected soil moisture content of 0-40cm soil layer, the differences decreased with soil layer depth increasing; plant height and dry matter weight were increased by 2.19%-15.06% and 0.59%-236.81% respectively over that of CK; grain and biological yield were significantly increased by 1.09%-14.76% and 0-25.27% over that of CK, and the effect of current year with the continuous use ofuse of humic acid is best, and the fourth-year effect of treatment only with the use ofuse of one-year humic acid had no significant differences compared with CK; water and fertilizer was similar to the variation of yield. In a word, the use of humic acid could improve the condition of soil water and fertilizer, make full use of limit water resource, increase yield, thus it could increase water and fertilizer use efficiency, and reduce environmental pollution, treatment by continuously using 4-year humic acid was best.

Large quantities of sand dunes occur along the NW and SE coastal belts which belong to very low rainfall Dry Zone coasts of Sri Lanka. The orientation depends on monsoonal wind directions, sand supply and wind strength. A scientific study on the dune sand deposits of the NW coastal belt in Sri Lanka was carried out to find out the suitability of the materials to be used for the construction industry in the Island. The distribution, thickness, type of materials and their physical properties were investigated in the field and some other tests were carried out in the laboratory. The laboratory analysis indicates that 95 % of the materials are quartz grains and the balance 5 % consists of a mixture of some heavy minerals, dust, clay, and fine sea shell fragments. Sand of fine to medium size with silt grains are sub-rounded to angular and tabular in shape. The degree of sorting and particle size of dune sands meets the soil properties required in the construction industry. The result indicates that dune sand could be effectively used in construction work without sieving and it is ideal for wall plastering due to its' uniformity. It could also be effectively used in concrete and in mortars mixing with coarse river sand and crushed rock sand.

This work focuses on the study of the effect of barley straws addition on the thermophysical properties of sand concrete intended for the construction of an external wall in arid regions. The work has been basically devoted to the study of the thermal properties of two river-dune sand concretes: one without barley straws (SC-W-BS) and another with barley straws (SC-BS). The effect of barley straws addition, wall thickness, air-gap within the wall, wall orientation as well as the wall surface coating on the time-lag (Phi) and decrement factor (f) of the materials have been discussed. The obtained results show that the addition of barley straws considerably improves the thermophysical properties of sand concrete (thermal conductivity, specific heat and density). In addition, the results obtained by the use of the EnergyPlus software and its application for an external wall made of these materials show that, in the case of SC-BS, the thermal insulation is markedly improved compared to the case of SC-W-BS. This thermal insulation is also improved when the thickness of the wall is higher and even a further improvement is possible if both faces of the wall are coated. Moreover, the addition of an air-gap within the wall, further improves its thermophysical behavior and the study of the wall orientation effect confirms the results of literature i.e. the south and east direction. Besides all that, the macro-structure of the studied composite appears relatively homogeneous with good adhesion 'straw-matrix'. (C) 2014 Elsevier B.V. All rights reserved.

The variability of climate in the South-West of Romania, in particular the lack of rainfall and low fertility of sandy soils, conduct to register in large surface important decreases of yields to the main crops. In this context, to promote sustainable agriculture in drought conditions, we have to found and recommend those species of plants that are more adaptable in existing thermo-hydric stress conditions and ensure good stability of yields obtained. The deepening drought in the south led to a chronic problem in southern Oltenia Plain, especially in area of sandy soils. Excessive droughts in 1992, 2000, 2002, 2007, manifested particularly severe in the South-West of Romania, was a typical example of a natural disaster. Harvests obtained in drought years were drastically affected and varied between 1-3 t/ha (maize), 1 t/ha (wheat), 500 kg/ha (soybean) and 500 kg/ha (sunflower) - [1]. Cowpea (Vigna unguiculata L. Walp) is one of the plants which recover with good results the biological potential of the mentioned area due to its resistance to drought and low claims against the natural fertility of the soil. Due to the high content of protein, both plant and grain, cowpea is considered the queen of areas with sandy soils, with multiple uses: human nutrition as pods or grains; improving soil fertility; inserting cowpea crop in rotation; using as green manure by cultivating the plant and in the stage of flowering and incorporating in the soil; through its participation in animal nutrition with sorghum or rye to obtaining of dried fodder and silage [2]. Because of biological and morphological particularities as: very strong root system with high power absorption, waxy coating on the leaves which would give a greater resistance to thermo-hydric stress conditions and the possibility of biological fixation of nitrogen thru symbiotic bacteria of Rhizobium genus, cowpea is successfully grown in different crop rotation on sandy soils area of Nigeria [3], [4]. Our research focused on increased resistance to drought, reduced requirements to soil fertility and high content of protein shows that cowpea can be a viable alternative for bean crop for human food and soybean crop used for animal feed, plants which are very sensitive to stress factors in areas with excessive drought.