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Knowledge of soil organic carbon (OC) components and enzyme activities is essential to maintain soil health and for sustainable land use during long-term vegetation restoration. The effects of vegetation restoration on soil physicochemical properties have been widely documented; however, knowledge of the relationships among soil OC components, enzyme activities, and soil properties in restored ecosystems remains unclear. Here, the soil from four successional stages of restored Robinia pseudoacacia vegetation (10, 20, 30, and 40 years) were sampled in China's Loess Plateau. The soil water content (SWC), bulk density (BD), pH, total nitrogen (TN), soil microbial biomass C (MBC) and N (MBN) contents, OC components (labile and recalcitrant OC), and soil enzyme (hydrolytic and oxidase) activities were measured. We found that restoration time significantly affects soil physicochemical properties, OC components and enzyme activities. Across the restoration time, the SWC decreased from year 10 to year 30, then increased from year 30 to year 40. Soil OC and TN increased with restoration time, while soil clay content decreased with restoration time. Following 40 years of restoration, soil MBC and MBN significantly increased by 214% and 88%, respectively. For OC components, 40 years of restoration significantly increased recalcitrant C component rather than labile C component. Soil hydrolytic enzyme activities significantly increased by 76.9% and 80.3% in 40 years stand compared with that of in 10 years stand, respectively, while soil oxidase enzyme activities significantly decreased with restoration time. Correlation analysis demonstrated that the SOC and MBC content significantly influenced soil recalcitrant C component and hydrolytic enzyme activities, while MBC and clay content significantly influenced soil oxidase enzyme activities. These results provided useful insights on the responses of forest restoration on soil OC components and related OC degrading enzymes and the understanding of soil C sequestration in the restored ecosystems in such areas. [ABSTRACT FROM AUTHOR]

Unraveling the distributions and controls of soil carbon (C) and nitrogen (N) accumulation is conducive to providing guidance for sustainable ecosystem management. Although the factors that affect soil C and N accumulation have been widely investigated, the relative importance of these factors and whether they confer direct or indirect effects remain unclear. Herein, we examined the distributions of soil organic carbon (SOC), soil inorganic carbon (SIC), and total nitrogen (TN) stocks across the 0–200 cm soil profiles in grasslands, forestlands, and shrublands on the Loess Plateau. Moreover, we determined the relative contributions of land use, topography, and soil properties (texture, water, phosphorus, and available nitrogen) to their variations. The results showed that with increasing soil depth, SOC and TN stocks decreased, while SIC stocks fluctuated. However, large amounts of SOC, SIC, and TN were stored in the deep soil layers (100–200 cm), with values of 3.06, 26.63, and 0.50 kg/m2, respectively. In the 0–200 cm soil layers, the total SIC stock was 53.40 kg/m2 and was 6.8 times higher than the total SOC stock. Among different plant communities, grasslands had the highest SIC stock (54.83 kg/m2), while Armeniaca sibirica and Robinia pseudoacacia had the highest SOC stock (10.06 kg/m2) and TN stock (1.49 kg/m2), respectively. Furthermore, approximately 85% of the variations in SOC, SIC, and TN stocks were jointly affected by land use, topography, and soil properties, in which soil properties acted as the most important driving factors, followed by topography and land use. In particular, topography affected SOC, SIC, and TN stocks mainly through its effects on soil texture and water. Overall, vegetation restoration scenarios incorporating grasslands and Robinia pseudoacacia are highly recommended and should be tailored according to specific topographic features. • SIC stock was 6.8 times higher than SOC stock in the 0–200 cm soil layers. • Grasslands performed better in soil C accumulation than forests and shrubs. • Land use, soil property, and topography explained 80% of the changes in C and N. • Land use played a less important role in affecting C and N than topography. • Topography affected soil C and N accumulation by influencing soil clay and water. [ABSTRACT FROM AUTHOR]

Highlights • Examine watering arrangements and intervals for water-saving and increasing WUE. • Grain yield was affected by irrigation intervals under double and single line a bed. • Highest value of water productivity was (7.4 kg m−3) achieved for 8-day intervals. • Water saving for 8-day were 6.7% and 65% compared to 12-day and surface irrigation. Abstract Uneven water distribution, misuse of water and inefficient watering techniques are some of the major causes playing devastation with water security, therefore, the aim of this work was to explore managing drip irrigation of wheat grown under heavy soil conditions as a tool for increasing crop yield, enlarging water productivity and saving irrigation water for newly reclaimed areas. A field investigation was conducted to study the impact of drip irrigation lateral arrangements (single and double lateral line a bed) and irrigation intervals (4-, 8-, and 12-days) on yield and water efficiency of wheat. Results revealed the grain yield was marginally influenced by irrigation intervals under double and single line a bed. As well, the grain yield got at 8- and 12-day intervals with double lateral line (8.28 and 7.62 Mg.ha−1, respectively), were higher compared with 4-day and the less grain yield was achieved by surface irrigation (control). Distributing water and salts were better under double lines a bed compared to single line under the same irrigation intervals. The highest value of water use efficiency of grain yield was 7.4 at 8-day followed by 6.62, 5.50 and 1.58 kgm−3 for 12-, 4-day and surface irrigation, respectively performed for double lines a bed with water saving 6.7% and 65% compared to 12-day and surface irrigation respectively. [ABSTRACT FROM AUTHOR]

Successful plant establishment is critical for the success of store/release cover systems. Such cover systems comprise several soil layers: highly compacted lower layers to isolate the waste; and nominally-loose upper layers to support vegetation. However, compaction of the upper layers under heavy machinery is often unavoidable, retarding plant growth and compromising the system's ability to capture infiltration. It is well known that compaction at different water contents imparts differing soil microstructures as well as densities. However, how to take advantage of those microstructures to mitigate compaction's effect on plant growth has yet to be investigated. This paper presents results for the growth of Avena sativa (oats) under different compaction conditions. Seeds were planted in soil columns comprising a sandy or clayey soil or layers thereof and allowed to grow under controlled climatic conditions for seven weeks. Plants were then extracted to examine the effects of compaction on plant features (root length and mass and shoot mass). Soil apparent hydraulic conductivity (unvegetated) was also measured. Results showed that compaction at the optimum water content, typical of geotechnical practice, was the most detrimental for plant growth. Rather, plant growth was greatest for compaction conditions which imparted both a lower dry density and hydraulic conductivity, for example typical of compaction at water contents above optimum. Results therefore highlighted the need to consider all facets of compacted soil texture when estimating the likely success of plant establishment. [ABSTRACT FROM AUTHOR]

This study investigates the potential of moss species for extensive green roofs to achieve very shallow substrate, low maintenance and low cost green roofs. The performance of four moss species (Didymodon constrictus, Eurhynchium hians , Polytrichum commune and Racomitrium japonicum) were assessed using three kinds of substrate: (a) a mixture of clay soil and compost, b) baked black soil and c) river sand for two years in Chiba, within the Tokyo region of Japan. The individual species were grown in monoculture in 4 cm depth of substrate in trays on a rooftop without supplemental irrigation using an onsite propagation method. Although all four species became dormant in conditions of high temperature and little rain, it was possible for all to establish and survive. R. japonicum showed the greatest coverage among the four species, reaching 70%–80% cover in the first four months. P. commune performed almost as well but took over a year to reach consistently high coverage. E. hians coverage fluctuated greatly in response to drought events. D. constrictus had low coverage overall but grew slightly more in the clay/compost soil; P. commune did poorly in sand substrate; R. japonicum and E. hians showed no consistent differences in how they were affected by substrate type. After two years only R. japonicum and P. commune had high enough coverage to consider further investigation. R. japonicum is already used in green roofing and wall applications. This study suggests that while some mosses show high performance across substrate types, others can be used on green roofs to achieve high cover, but only after determining a suitable substrate type. These results can inform moss species selection for green roofs in Japan, however, this methodology can be applied in other regions to establish moss green roofs. An onsite propagation method can be used to establish moss green roofs but further research is needed to identify means of increasing onsite growth rates for more species. [ABSTRACT FROM AUTHOR]

Pavements, rooftops and compacted soils inhibit rainfall infiltration across our cities and drains built to prevent flooding can further reduce water availability to urban ecosystems. These hydrological changes diminish the provision of ecosystem service benefits to local populations and negatively impact downstream communities and environments. Stormwater engineering can help restore infiltration, but little use has been made of infiltration systems in expansive clay soil (often referred to as reactive clay), due to the potential for problematic shrinking and swelling soil movements in response to changes in soil moisture. In an experiment in South Australia, ground movement and moisture variation were monitored in moderately reactive clay soil beneath pervious and impervious paving, revealing that soil moisture and ground movement were influenced by interactions between pavement treatment, the design of the pervious pavement's gravel base layer, the size and proximity of trees, and the season. Where there were no tree influences, water-related ground movement was smaller near impervious paving, but ground movement was smaller near pervious paving at sites near trees. The differences in ground movement between pervious and impervious pavements were small when compared with the amplitude of ground movement observed at pervious and impervious pavement treatments between summer and winter. • soil was typically drier beneath permeable paving than impermeable paving. • infiltration marginally reduced reactive ground movement near trees. • infiltration through permeable paving into reactive clay was not problematic. • soil water extraction by trees increases infiltration capacity of clay. [ABSTRACT FROM AUTHOR]

• The management factors affect the carbon sequestration process. • Soils with more clay content had high sequestration capacity. • The highest and lowest amount of stored carbon was found in stem and leaf tissues. The present study was conducted to examine how different organs of plants (leaf, stem and root) of Tamarix aphylla and Tamarix kotschyi could affect carbon sequestration in soil depths ranging from 0 to 15 cm and 15 to 30 cm. This study was carried out in the Ahoochar region, 25 km north of Shiraz, during 2015–2017. This study was carried out in two separate factorial experiment arranged in a randomized complete design. The first factor was the type of plant species in both experiments. The second factor was the plant organs in experiment I and different soil depths in experiment II. The results showed that there was a higher degree of carbon sequestration in depths that ranged from 0–15 cm, compared to soil at 15–30 cm depth. The results of correlation coefficients showed that the percentage of clay was the strongest parameter that contributed to carbon sequestration. Furthermore, Tamarix aphylla and T. kotschyi showed similar amounts of organic carbon stored in their tissues. Stems had higher amounts of stored organic carbon compared to the leaves. In general, it was observed that carbon sequestration reached its highest level (54.15 t/ha) in soil with T. kotschyi at 0–15 cm depth. The stem of both plants had a higher ability for carbon sequestration. [ABSTRACT FROM AUTHOR]