Most developed lands in arid and semi-arid areas of Algeria rest on a highly mineralized phreatic aquifer, the level of which is close (0-1.5 m) to the ground surface. Such a superficial water table, combined with the existence of highly severe climatic conditions, have enhanced the process of evaporation from the water table, which largely contributes to the salinization of soils and the degradation of the environment. The present study on the evaporation process of the phreatic aquifer in the Ouargla region shows that evaporation decreases the further the water table is from the ground surface. The study shows that evaporation of the water table reaches its maximum and is equal to the rate of evaporation of the aquifer at 0-0.6 m from the ground surface and its minimum rate when it is below 1.7 m. For better development of land and improved agricultural production, it is necessary to know the critical depth of the water table for which evaporation is low and therefore there is a low deposit of salts in sandy soils in the arid Ouargla region.

Peanut (Arachis hypogaea L.) is an important grain legume whose yield is often limited by water deficits because it is commonly grown in regions with intermittent rainfall and on sandy soils with low water-holding capacity. Annual peanut yield loss due to drought worldwide has been estimated at US$520 million (Sharma and Lavanya 2002). To increase yields, it is essential to develop genotypes that can sustain growth and yield when subjected to water deficit (Sinclair and Vadez 2012). The two plant traits, which are the topic of this book, have been identified in peanut to result in conservative use of water and allow sustained growth during drought: (1) earlier closure of stomata in the soil drying cycle resulting in decreased daily transpiration rate and (2) limited-transpiration rate (TRlim) under high atmospheric vapor pressure deficit (VPD) (Devi et al. 2009, 2010).

The paper deals with evaluation of the lodgepole pine research provenance plot in the pine site conditions in Trebon (Southern Bohemia, Czech Republic) at the age of 34 years. Based on the evaluation of specific quantitative and qualitative traits (height, DBH, stem volume, tree stock, mortality, defoliation, stem form and height of stem forking, branch thickness, and bark type), provenances were assessed in terms of their production capacity and utilization on extremely dry sandy soils. The lowest defoliation (20-25 %) has been recorded in the case of provenances No. 2089 Manzanita, No. 2235 Calling Lake and No. 1902 Mile 86, most others did not exceed a level of 50 %, but four provenances had a high needle loss (71-79 %). From the volume production point of view, the provenance No. 2089 Manzanita (P. c. subsp. contorta) from the Oregon coast and No. 2091 Mount Hood (P. c. subsp. latifolia) from Oregon Cascades, demonstrated their high production ability. The best-growing provenance No. 2089 Manzanita corresponds through its growth characteristics to the fourth relative site class of domestic Scots pine, which confirms that proper selection can find suitable provenances that can fulfill the production function even in poor and dry site conditions.

In this study, soil critical temperature was measured using two distinct approaches: (1) a temperature profile established from a heating element located at the top of a vertical column and (2) temperature and moisture profiles induced from a centrally placed heating source in a 'horizontal' apparatus. Steady-state thermal and moisture equilibrium took longer to establish in the horizontal apparatus (on average, nine hours longer); however, the resulting temperature and moisture profiles were more consistent in the horizontal apparatus and with easily discerned slope discontinuities between the dry and moist zones. More ambiguous temperature profiles were observed in the vertical apparatus, even with insulation and heat tape applied to minimize horizontal boundary losses. This is indicative of the difficulty in maintaining one-dimensional heat flow in a vertical column. As soil critical temperature is an important parameter used in designing underground infrastructure impacted by significant heat transfer, such as buried power cables, refinement and standardization of equipment and protocol for determining this parameter in a precise and mechanistically sound manner is of prime concern.

This paper addresses the evaluation of the potential use of ash from rice peel as pozzolanic material acting together with hydrated lime in the chemical stabilization of a residual soil from the Ilha Solteira region, Sao Paulo State, Brazil. Ash contents of 5% and 10% were added to a soil previously stabilized with 8% of hydrated lime, all contents related to soil dry weight, in order to evaluate soil and mixtures performances regarding geotechnical indexes (grain size distribution, liquid limit (LL) and plastic limit (PL)), optimum compaction parameters (optimum water content (w(ot)) and specific apparent maximum dry mass (rho(dmax))) determined at the standard proctor compaction effort, as well as classification of the soils and its admixtures following the MCT Methodology. Data from the testing program lead to the conclusion that addition of ash generated: (i) increases in the parameters LL, PL and w(ot), as well as reductions in the parameters plasticity index (PI) and rho(dmax) of the soil and its admixtures; (ii) the soil and its admixtures were classified as lateritic sandy soils (LA') following the MCT Methodology.

In situ edaphic factors affecting seed germination and seedling emergence of three framework species of Acacia were investigated with the intent of developing fundamental and scalable restoration capacity for Arabian dryland restoration. Direct seeding represents the most efficient means to restore vegetation at the landscape scale and this study provides insight into edaphic and ecological limitations, as well as effective protocols governing the use of native seeds for restoration in hyper-arid environments. The study was conducted in extant Acacia woodland habitat on conserved land (Thumamah Nature Park) in close proximity to Riyadh, Saudi Arabia. Broad-scale direct seeding using un- and pretreated Acacia gerrardii, A. tortilis, and A. ehrenbergiana seed, and two seed burial depths were implemented across three sites with distinct soil surface characteristics. Eight weeks post-sowing, random samples for each species x seed treatment x burial depth combination were excavated, sieved, and categorized as follows: failed to germinate, germinated but died prior to emerging, or successfully emerged. We show that germination and emergence of Acacia gerrardii, A. tortilis, and A. ehrenbergiana were driven by a three-way interaction among species, site, and seed burial depth. Treating seed with the signaling compound Moddus did not have a definitive effect, positive or negative, on any of the species investigated. Acacia gerrardii was the only species that exhibited widespread emergence, though emergence was not consistent across sites or burial depths. Germination was highest in disturbed soil (up to 69% for A. gerrardii), but very few (< 2%) successfully emerged; a greater proportion of germinants in sandy soil emerged (up to 44% for A. gerrardii) even though the overall germination was less. Though species-dependent, a 2-cm sowing depth was most effective in sand; while in disturbed soil, sowing depths of 1 and 2 cm were comparable; and no germination was observed in gravelly clay soil. Sandy soil exhibited rapid water infiltration (107.6 mm min(-1)), and post-sowing surface crusting was a non-factor (0.44 kg cm(-2)). Disturbed soil exhibited moderate water infiltration (1.46 mm min(-1)) and post-sowing surface crusting was double that of sand (0.88 kg cm(-2)) and restrictive on seedling emergence. Gravelly clay exhibited extremely poor water infiltration (0.12 mm min(-1)), and surface crusting was severe (4.49 kg cm(-2)) and an order of magnitude greater than sand. The medium-coarse sand fraction, a key driver of the observed soil surface processes, was greatest in sand (55%) and significantly less and uniform in the disturbed (22%) and gravelly clay (22%) soils. Our findings demonstrate that soil surface characteristics and associated processes can dictate ecological processes at depths as shallow as 1-2 cm, and that soil crusts that slow water infiltration and impede seedling emergence rapidly reconstitute after disturbance; both are important considerations for restoring dryland vegetation.

Changes in growth, leaf contents of proline, oxidative stress-related parameters, and phenolic compounds, and antioxidant activities were investigated in the halophyte species Sesuvium portulacastrum L. under saline conditions. Rooted cuttings were individually cultivated in sandy soil. After five weeks of pre-treatment, seedlings were submitted during one month to different salt concentrations ranging from 0 to 800mM NaCl. The plant growth was significantly improved by salt at 200-600mM concentration. This trend was associated with (i) the stimulation of photosynthetic activity, (ii) the protection of membrane integrity (leaf MDA content 50% lower than the control), and (iii) higher total antioxidant activity, especially at 400mM NaCl. At this salt concentration plants accumulated high contents of proline, polyphenols, antocyanins, and carotenoids. These compounds could be implied in the protection of the photosynthetic system and in the improvement of growth. Exposure to 800mM NaCl impaired significantly photosynthesis, proline, polyphenol, antocyanin, and carotenoid accumulation. Yet, the strong antiradical activity (DPPH) observed at this extreme salinity might partly explain the plant survival. S. portulacastrum could be used in the rehabilitation and the stabilisation of saline or saline arid land. Additionally, under saline conditions, S. portulacastrum accumulate a large amount of proline and exhibits important antioxidant potentialities.

In this study, we examined the efficiency of a kaolinite clayey soil to mitigate water repellency of a sandy soil with olive trees. The treatment was applied to the soil zone below the tree canopy, which displayed the highest degree of water repellency [average water drop penetration time (WDPT) value=820s]. Both dry (incorporated onto the top soil) and wet clay applications (after dispersion in irrigation water) were examined in a replicated experiment, with control trees being used for comparison. The application rate of the clayey soil was maintained in both cases (wet and dry mode) equal to 1kgm(-2), while the effect of subsequent wetting and drying cycles on the treatment performance was evaluated. The results of the study verify that clay application was effective to mitigate soil water repellency. Dry supplementation displayed low efficiency (26% reduction of the air-dry WDPT compared with the control soil) within the first week of application. The efficiency of the dry-clay treatment increased to 76% after applying three subsequent wetting and drying cycles. In comparison with the dry mode, the wet clay was efficient immediately after application (74% reduction of the WDPT), indicating that the limiting step in the overall process was clay dispersion. Based on the findings of this study, it was proposed that wet clay application is of interest for controlling soil water repellency in agricultural land. Copyright (c) 2016 John Wiley & Sons, Ltd.

The red sand dunes appear along the south east, -west coast of Tamil Nadu, India between the latitudes and longitudes of 8 degrees 07'56N to 8 degrees 22'11N; 77 degrees 19'84E to 77 degrees 53'40E. The dune sands from this region were studied through magnetic methods such as magnetic susceptibility measurements and acquisition of isothermal remanent magnetization, geochemistry and X-ray diffraction methods. Optically stimulated luminescence (OSL) dating method was used to constrain the chronology of deposits. Three sections were excavated up to 5-9.5 m with one inland deposit (TPV) and two near coastal sections (THOP and MUT). The magnetic parameters show both significant contribution of hematite structures and indicate the presence of multi-domain magnetite or mixed mineral contents of magnetite and anti-ferromagnetic minerals in the sample. The occurrence of magnetite in THOP and TPV sections is possibly due to the marine sediments transported by sturdy onshore winds. In XRD data, correlation analysis indicated TPV and MUT sections have a similar type of deposition and THOP did not show any positive correlation with TPV and MUT and even with its own deposition. In comparison with geochemistry data, chi variation and OSL dates, it was shown that the sample MUT21 (200 cm) with an OSL age of 14 +/- 2 ka indicated deposition during the humid interval and at similar to 17 +/- 2 to similar to 19 +/- 2 ka MUT61 (600 cm) depicts the dry period of deposition.

Strategies to promote dense, deep root systems are important for the efficient use of water and nitrogen fertilisers in subtropical loamy sandy soil. This study assessed the effect of interactions between irrigation method (drip and furrow), irrigation level (full and reduced), and nitrogen fertiliser type (quick release and slow-release) on root growth of maize (Zea mays L.) and the associated effect on grain yield, aboveground biomass and leaf area index. Factorial field experiments on semi-arid loamy sandy soil in Mozambique was carried out in four cropping periods (two in the hot-wet season, two in the cold-dry season). The response to the management factors at three growing stages of coarse (>= 0.7 mm diameter) and fine (<0.7 mm diameter) root density (RD) (two cropping periods) and maximum rooting depth (four cropping periods) were measured in situ by modified profile wall method. The interactions between management factors did not explain the variation in maize RD or maximum rooting depth. However, seasonal variation between the cropping periods affected the distribution of coarse RD. Drip irrigation gave 33-153% higher coarse RD and 26-55% higher fine RD than furrow irrigation in deeper layers (16-64 cm), whereas furrow irrigation gave 21-40% higher coarse RD than drip at a shallow depth (0-16 cm). Irrigation level had little effect on RD, whereas slow-release fertilisation resulted in overall higher RD, aboveground biomass and grain yield than quick-release fertilisation in the cold-dry season. RD or maximum rooting depth showed few significant correlations with grain yield, biomass and leaf area index, respectively, but higher RD generally tended to result in higher yield. Overall, drip irrigation combined with reduced irrigation and slow-release N fertiliser appeared to be the most promising strategy to promote maize rooting and increase yield, especially in the cold-dry season. (C) 2016 Elsevier B.V. All rights reserved.