Cohesionless soils such as sandy or silty soils are more susceptible to landslides, slope failures, and erosion in comparison with cohesive soils containing clayey fraction. While vegetation roots are known to provide erosion resistance, shear strength properties of cohesionless soils with grass roots and their effect on slope stability needs more investigations. Therefore, it was decided to test soil specimens of cohesionless soils with and without grass roots in the laboratory. The objective of the testing program was to quantify the effect of grass roots on cohesion and angle of internal friction of the sandy soils. Direct shear tests were conducted on specimens (with and without grass roots) consisting of three types of soils: (i) natural fine silty sand, (ii) clean sand with medium and subangular particles, and (iii) clean sand with angular coarse-grained particles. The effect of grass root was more pronounced in fine silty sand with about 210% increase in cohesion and about 13% increase in the angle of internal friction. The test results indicated that the presence of grass roots increased the cohesion by an average of 119% while the angle of internal friction was found to have increased by an average of 12% among the soils tested. For the tested sands, the inclusion of grass roots was found to increase the factor of safety by 550% for slopes in dry conditions, whereas the factor of safety increased by 525% for slopes with seepage conditions.

The current study was carried out on Iraqi lands, which is located between latitudes 29 degrees 00' to 37 degrees 15' N and longitudes 38 degrees 45' to 48 degrees 25' E and extended over an area of 436364 square kilometres. The study period is characterised by frequent drought conditions and scarcity of herbaceous crops for many years. The study aims to cast light on the impact of drought on vegetation cover using Standardised Precipitation Evapotranspiration Index (SPEI) and Normalised Difference Vegetation Index (NDVI) data. Required data are downloaded from Global SPEI database and Copernicus the Global Land Services. The spatial interpolation of the SPEI and NDVI are used for comparing drought conditions and the percentage of vegetation cover. The results point out to six years of dry conditions i.e., 1999, 2000, 2008, 2009, 2011 and 2012 during which most of Iraqi regions passed through moderate to extreme drought conditions with a significant decrease in vegetation cover. Measurement of the correlation coefficient marked moderate to very high correlation over areas where herbaceous crops are dominant, except areas in middle-south which show weak correlation due to dependence on irrigation process while southwestern parts due to the presence of sandy soil and north-eastern parts; because of dominance of wet-cold climatic conditions.

Sandy desert soil in Sudan are characterised by low content of organic matter, small water holding capacity and low crop productivity. Methods to enhance crop productivity on these environments, such as land application of composts, are of great importance. Field experiments were conducted on a sandy soil to determine the effects of two types of composted manures on growth and yield of two sorghum varieties grown under rainfed conditions. Two sorghum cultivars (Butana and Arfa Gadmak were sown under chicken manure (CM) compost (5 t ha(-1)), CM compost with NPK (36 kg ha(-1)), farm manure (FM) compost (20 t ha(-1)), FM compost with NPK (36 kg ha(-1)), CM compost with FM compost (1:1, wt/wt, 12.5 t ha(-1)), CM and FM composts with NPK (36 kg ha(-1)), only NPK (36 kg ha(-1)) and control (no composts or NPK). Application of composts increased organic soil carbon by 50% and available phosphorous (P) between 43 to 105%, whereas, pH and bulk density were decreased by 2 and 6%, respectively. Soil moisture contents in compost treated plots were 56-98% higher than control plots. Mixing compost with NPK increased leaf area index over NPK alone by 28% but the highest values were found in plots treated with chicken compost or integrated with NPK compared to NPK application alone. Incorporation of compost increased dry matter yield compared to control by 17-53% and increased grain yield by 1.8 to 3.1 fold in both sorghum varieties. Grain yield from plots treated with NPK, sole chicken compost or combined with NPK were similar for both varieties in both seasons. In general, the trend of grain yield of sorghum was in the order of NPK = chicken compost with NPK = chicken compost = farm manure compost with NPK > mixed compost with NPK = farm manure > control. In conclusion, integrating composts with NPK improved fertility of sandy soils, sorghum growth and yield. (C) 2020 Friends Science Publishers

Based on the data of China's economic and social big data platform from 2000 to 2019, this paper studies and analyzes the development status and influencing factors of desertification in Maowusu sandy land in China. Based on the exploratory analysis (EFA) and the dummy variable regression model (DVRM), the research result shows that the annual precipitation is the main climate factor affecting the vegetation coverage in this area. And for every 100 mm increase in annual precipitation, vegetation coverage will increase by 10%. In addition, the annual average temperature also has a significant impact on the vegetation coverage. For every 1 degrees C increase in the annual average temperature, the vegetation coverage will increase by 2.5%. Analysis of policy factors shows that the policy effects of the 2005 National Desert Control Plan (2005-2010) and the 2011 National Desert Control Plan (2011-2020) etc. can increase vegetation coverage by 3.4% and 4.7% respectively compared with the base period level in 2000. The study reveals the important role of climate and policy factors in the reversion of desertification in Maowusu sandy land. The study is of great significance and value to desertification management and related policy-making in China.

Soil testing guidelines for sulfur (S) under dryland cropping in south-eastern Australia are not well developed. Our objective was to assess the value of soil and tissue tests for S and nitrogen (N), because the two minerals frequently interact), in predicting S-deficient sites and hence increasing the probability of response to application of S (and N). Here, we report three proximal experiments in 2014-16 for barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) on a sandy soil in a semi-arid environment near Merriwagga in western New South Wales. The trials contained a factorial combination of four rates of each of applied N as urea and S as high-grade gypsum. Responses to S were obtained for dry matter (DM) quantity and nutrient content at flowering in 2014, but no grain-yield response was obtained in any year. DM response to applied S was obtained when the concentration of S in the DM was increased from 0.08% in barley and 0.09% in wheat without S application to 0.10-0.11% in both crops with S applied as gypsum. Because we obtained no grain-yield responses to applied S, the 0.10% S in grain was likely to have been adequate for both crops in these experiments. A pool of subsoil S was accessed during each season and this compensated for any DM deficiencies of S by the time of grainfill. Shallow soil tests (0-10 cm) for S can therefore indicate sufficiency but not necessarily deficiency; therefore, in grain-cropping areas, we recommend soil S tests on the same samples as used for deep N testing (to 60 cm) and that an S-budgeting approach be used following the soil tests. Furthermore, for marginal nutritional circumstances such as occurred in this study, the supporting use of N : S ratio is recommended, with values >17 in DM or grain likely to indicate S deficiency for both barley and wheat.

This article addresses the phytocoenotic diversity of psammophytic grass communities in the southern part of the nonchernozem zone of Russia, where the restoration of Scots pine (Pinus sylvestris) is either ongoing or potentially possible. Community structure and composition formation trends developing under the influence of key environmental and coenotic factors have been identified. The studies were carried out in Bryansk, Kaluga, and Smolensk oblasts in 2010-2018; over 150 geobotanical releves of psammophytic grass communities have been produced. This vegetation belongs to the class Koelerio-Corynephoretea Klika 1931, which combines dry grasslands on sandy soils and rocky outcrops in the temperate and boreal zones of Europe, on islands of the North Atlantic, and in Greenland. Differences between environmental regimes of various habitats occupied by psammophytic communities have been identified. In most cases, the environmental amplitudes of syntaxonomic units vary significantly by the three key edaphic factors (moisture, soil reaction, and soil richness in mineral nitrogen) and form pretty compact environmental spaces: within each syntaxon, numerical values of the above factors, expressed in score points, normally vary within a narrow range. Regression analysis has established that the species richness of psammophytic communities depends statistically significantly only on the mineral nitrogen supply and soil moisture. Based on the statistical analysis results, the number of Pinus sylvestris plants of any age does not depend on the species richness in the community, total projective cover of the grass stand (excluding the Scots pine), separately calculated moss and lichen projective covers, and average numerical values of environmental factors identified by H. Ellenberg in the community. It is established that numbers of pine trees on study sites depend on only one factor: distance from the diaspora source determining the invasion possibility. The data on the phytocoenotic and floristic diversity of the psammophytic grass vegetation are to be incorporated into the unified database on the southern part of the nonchernozem zone of Russia to identify environmental and botanical-geographical features of this plant community type in the region.

Soil CO2 emission is one of the most important components of the global carbon cycle. This study analyzes the seasonal dynamics of soil emission for various land cover types in the middle taiga subzone of central Siberia during five growing seasons. It is shown that, throughout a vast area covered by pine forests and their derivatives formed on sandy soils, seasonal CO2 emission values are determined primarily by the moisture conditions and only secondarily by the temperature regime and ecosystem type. The effect of the forest type is manifested only under the most favorable moisture conditions. A new approach is proposed: divide the growing season into dry and moist periods depending on the threshold soil moisture for areas with different vegetation types.

The study was conducted on sandy soil, which is located in the Agriculture College of Thi-Qar University to determine the effect of the type and level of organic fertilizer (O. F) on the quality and yield of chard. The composts which are used during the study were local compost (Al-Shatra) by two levels which are 1 and 2 kg/m(2), local compost by two levels 1 and 2 kg/m(2) area for foreign compost by two levels which are 1 and 2 kg/m(2) area and a mixture of local compost and foreign. Cultivation was conducted in the field, the design of experiments was Complete randomized block design, nine treatments and three replications were used in the experiments. The best treatment at reducing ammonia volatile was (la) treatment (2 kg/m(2) foreign fertilizer), the most ammonia volatilization period occurred at the third week which was 5866.79 mgNH(3)/m(2) area. All types of organic fertilizers and levels performed significantly in the reduction of ammonia volatiles values from the soil and increase plant height, leaf surface area, chlorophyll, dry and wet materials for chard's plants.

The main objective of this study is to enhance the performances of local materials in order to be used in road construction sector. To enhance the performances of this local materials, the strategy adopted is to combine the beneficial effects of mixing different materials and treatment using binders. The materials used in this study are tuffs and dune sands. Hence the present work is also a contribution to the co-valorisation of local materials in arid region of the south of Algeria. According to the results obtained, it is shown that the tuffs of the Saharan regions are suitable for the use of Saharan pavements, particularly in base layers and foundations. The incorporation of dune sand up to 20% improves the mechanical performance. The binders treatment (cement, lime and cement/lime) have induced a further improvement in bearing capacity and compressive strength as well as tensile strength. With these improvement, the materials could be used in roads with heavy and important traffic.

Pleistocene loess of the Rhone Valley and Provence region, disconnected from the two main European aeolian systems (North European Loess Belt and Danube basin), are of interest to test the impact of source variability, grain size sorting, weathering and sediment recycling on the geochemical composition. The concentration of major, trace and rare earth elements in loess and potential sources was analysed through Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and ICP-Mass Spectometry (ICP-MS). Analyses show a genetic relationship between loess and the Ca-rich river sediments from the Alpine Ice Sheet (AIS). The loess of Provence show distinctive properties with a higher CaO and MgO content and a higher Europium anomaly (Eu/Eu*), suggesting sources richer in dolomite together with a contribution from mafic rocks (Alpine ophiolite complex). The homogeneous loess composition, compared to alluvial sources, reflects particle mixing during transport in the atmosphere. At the European scale, the geochemical composition of loess changes according to regions, but remains consistent within each region. Such variability is mostly related to the composition of rocks outcropping in respective catchments and especially in areas covered by ice sheets. The Chemical Proxy of Alteration (CPA) and Rb/K ratio suggest a weak chemical weathering linked to the cold and dry conditions typical of the Last Glacial. Recycling of older aeolian formations possibly caused loess enrichment in resistant minerals and quartz, especially for loess derived mostly from the abrasion of aeolian sand (Aquitaine).