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  • 1
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    OFFSETTING LAND DEGRADATION THROUGH NITROGEN AND WATER MANAGEMENT DURING MAIZE CULTIVATION UNDER ARID CONDITIONS (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-14
    Description: The best management of soil, irrigation and crop nutrients are among major components of sustainable agriculture that reduces groundwater contamination, prevents soil degradation, and guarantees the best resource use efficiency. Trials were conducted to optimize maize ( Zea mays L.) yield by experimenting various irrigation water regimes, Nitrogen (N) application rates and methods in ninety-six pots under arid environmental conditions during autumn 2012. Crop hydrological and agronomic characteristics were assessed under a completely randomized design with factorial arrangements. Water and N stress to the plants under observation significantly reduced the water potential, osmotic potential and turgor pressure of the leaves. Crop growth rate and total dry matter production were significantly improved by an increase in N fertilizer application up to 300 kg ha -1 (equivalent to 4.8 g N pot -1 ) for all water regimes. Grain per cob, 1000 grain weight, and final grain yield were higher at 100% field capacity with the application of 300 kg Nha -1 under the soil N application method than those under foliar N application treatments. The best N rate for optimum grain production was attained by 300 kg ha -1 with 575 mm supplemental irrigation water ha -1 . The quadratic equation fitting revealed that the effect of N on crop growth parameters was higher than that of the supplemental irrigation; therefore, a water deficit may partly be managed by adding N to the soil. These water and N managements may be used in formulating agricultural practices to avoid degradation of lands for soil and environmental conditions similar to those of the current study warranting a field research.
    Print ISSN: 1085-3278
    Electronic ISSN: 1099-145X
    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 2
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    PLANT GROWTH AND OIL CONTAMINATION ALTER THE DIVERSITY AND COMPOSITION OF BACTERIAL COMMUNITIES IN AGRICULTURAL SOILS ACROSS CHINA (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-09
    Description: The dynamics of microbial diversity in response to biotic and abiotic disturbances provide a sensitive indicator for evaluating the potential stability and degradation of soils in agro-ecosystems. To determine the effect on soil bacterial communities of disturbances by plant growth ( Robinia pseudoacacia ) and oil contamination, we sequenced 16S rRNA genes using MiSeq technology. A greenhouse experiment was conducted using 21 agro-soils from 19 provinces in China. Abiotic and biotic disturbances, including treating the soils with sterile water, crude oil, and/or an invasive plant, altered the bacterial community structure in the soils, increased bacterial richness, and reduced bacterial dispersion. Oil contamination exerted stronger effects on the bacterial α - and β -diversity than plant growth. The different responses of bacterial communities and the core microbiome indicated that the disturbances shifted the prevalent soil microbial groups in agro-ecosystems. Among different sampling sites, community dissimilarity increased with spatial distance. Edaphic factors (deterministic processes) exerted the primary influence on the assembly of soil microbiomes in agricultural fields, while geographic factors (stochastic processes) were less influential. The bacterial communities in agro-soils from warmer regions were more sensitive to the disturbances. This study provides new insight into the alteration of soil microbiota by plant growth and oil contamination in agro-ecosystems across a large spatial scale.
    Print ISSN: 1085-3278
    Electronic ISSN: 1099-145X
    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 3
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    An Estimation of the Extent of Cropland Abandonment in Mountainous Regions of China (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-09
    Description: With the wages for migrant workers increasing dramatically in China since 2003, the size of the agricultural labour forces has been shrinking rapidly. Intensively substituting agricultural machinery for the shrinking farm labour force is hardly possible for croplands in the mountainous regions of China where mechanization is difficult to achieve due to small field size and rough terrain. This has eventually led to cropland abandonment in these regions. Considering the high pressure for food security in China, cropland abandonment in the mountainous regions should not be ignored. By employing a novel method, this study estimates the extent of recently abandoned croplands (period 2000-2010) and the changes that can be expected in the future in China's mountainous areas. The results show that the total extent of abandoned croplands in Chinese mountainous counties during the period 2000 to 2010 is estimated at 147 million mu (1 mu=666.67m 2 ); in total, about 28% of croplands in mountainous counties was abandoned, including croplands converted in the Grain for Green Programme (GGP). With three scenario assumptions, a sizeable extent, 114 to 203 million mu, of croplands may be abandoned from 2010 to 2030 with the rapid decrease and aging of projected farm labour forces. This could exacerbate the future challenges of maintaining China's food security. A substantial increase in agricultural project investments, including land consolidation and agricultural productive fixed assets, especially micro-tillage machines, could help mitigate the risk of cropland abandonment. Additionally, land-use and environmental policymaking should take into account the expanding cropland abandonment in mountainous regions.
    Print ISSN: 1085-3278
    Electronic ISSN: 1099-145X
    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
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    Effect of stand origin and slope position on infiltration pattern and preferential flow on a Loess hillslope (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-07
    Description: Preferential flow is expected to provide an important pathway to replenish soil water at deep soil layers in arid or semi-arid areas; however, few studies have addressed this topic, especially in semi-arid Loess hillslopes. This study aimed to quantify the effect of stand origin and slope position on the contribution of preferential flow to total infiltration and spatial variations in water flow. A blue dye tracer experiment was conducted to visualize water flow in Robinia pseudoacacia plantation (PL), natural forestland (NF) and natural grassland (NG) at the upslope, midslope and downslope, and semivariance analysis was used to determine spatial variability at the centimeter scale. The results showed that role of macropore flow was dominant in upslope and midslope, and larger in NF than that in PL and NG, due to presence of abundant root systems in upper soil of NF. Moreover, contribution of preferential flow at the upper slope in NF was larger than that in PL. At the downslope, the role of rock fragments coverage (RFC) at the downslope was emphasized, leading lateral flow dominant at the downslope in PL and NG. In addition, contribution of preferential flow and vertical variability of infiltration at the downslope in PL was higher than that in NF, The findings demonstrate that compared with PL, NF has a more positive impact on increasing infiltration and preferential flow which can replenish deep soil water, and reducing surface runoff and soil erosion. The presence of RFC can make lateral flow dominant at the downslope on the Loess hillslope, related to water movement along the slope toward streams and catchment outlets.
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    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 5
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    WIND EROSION REDUCTION BY WATER DIVERSION IN THE LOWER HEIHE RIVER BASIN, NORTHWEST CHINA (2018)
    Wiley-Blackwell
    Details
    Publication Date: 2018-03-06
    Description: The Lower Heihe River Basin (LHRB), a key ecological function zone in northwest China, has suffered from serious land degradation by wind erosion for decades, posing a great threat to the national ecological safety. This study explores dynamics of wind erosion and the soil conservation service (SCS) in this region following water diversion during 2001-2010 with the Statistic Model of Wind Erosion on Small Watershed Basis based on remote sensing, climate and soil data, and impacts of driving factors on the SCS are revealed with scenario analysis. Results suggest the SCS represented by the soil retention amount was less than 500 tons km -2 y -1 in most parts of the study area and higher than 15,000 tons km -2 y -1 in a few wind erosion hotspots, including the East Juyanhai region, Dingxin Oasis, Ejina Oasis and its surrounding desert-oasis transitional areas. The cumulative potential soil loss of the study area increased much faster than the cumulative soil retention amount, and fractional vegetation cover influenced by the Ecological Water Diversion Project played a dominant role in improving the SCS, accounting for 82·25% of the change in the SCS of the study area. Climate change played a subordinate role, but there were essential separate and interactive effects of climate factors on the SCS. This study provides a preliminary overview of hotspots of wind erosion and the SCS in the LHRB from a geographical perspective, laying a solid basis for combating land degradation by wind erosion in arid regions of northwest China.
    Print ISSN: 1085-3278
    Electronic ISSN: 1099-145X
    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
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    INFLUENCE OF DIFFERENT SEWAGE SLUDGES AND COMPOSTS ON GROWTH, YIELD AND TRACE ELEMENTS ACCUMULATION IN RICE AND WHEAT (2018)
    Wiley-Blackwell
    Details
    Publication Date: 2018-03-06
    Description: The use of sewage sludge (SS) and solid waste composts in agriculture is considered as one of the best disposal options. In this study, impact of different composts and SS was evaluated on the soil quality, growth and yield performance of rice and wheat crops. Four types of composts and SS were collected from different sources and applied in soil at 0.5% (5 g kg -1 soil) and 1.0% (10 g kg -1 soil) in comparison with chemical fertilizer (no SS/compost). The application of all types of composts at all the tested rates increased the straw and grain yields of both the crops compared to control. Nevertheless, application of Lahore compost and all SS (1.0%) resulted in a significant increase in the concentration of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in plant parts. The Cd concentration in rice grains with Lahore compost and Kasur SS applied at the rate of 1% was above the safe limit. The trace elements in wheat grains with all composts and SS at all the tested rates remained within safe limits. The release of amendment bound trace elements in soil solution was highly dependent upon dissolved organic carbon and concentration of these trace elements especially for Cu and Zn. Application of SS at low level (0.5%) and compost (except Lahore compost) at both levels could be a better strategy to exploit their benefits in terms of crop performance and soil quality. However, application of SS and compost at high rates may lead to accumulation of trace elements in rice grains limiting its suitability for human consumption.
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    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
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    The Role of Rapid Glacier Retreat and Landscape Transformation in Controlling the Post-Little Ice Age Evolution of Paraglacial Coasts in Central Spitsbergen (Billefjorden, Svalbard). (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-06
    Description: .In Svalbard, the rapid glacier retreat observed since the end of the Little Ice Age (LIA) has transformed the geomorphology and sediment budgets of glacial forelands, river valleys and slope systems. To date, relatively little information exists regarding the impact of such a profound glacial landscape degradation on the evolution of coastal environment. This paper addresses this deficiency by detailing the post-LIA sediment fluxes to the coastal zone in Billefjorden, central Spitsbergen (Svalbard). We analysed the response of the gravel-dominated barrier coast to the decay of Ferdinandbreen, one of the fastest retreating glaciers in the region. Glacier retreat resulted in the development of paraglacial sediment cascade where eroded and reworked glacigenic sediments progressed through alluvial fans to the coast, thus feeding gravel-dominated spit systems in Petuniabukta. We demonstrated the that coastal systems in central Spitsbergen responded abruptly to post-LIA climatic changes. The acceleration of coastal erosion and associated spit development was coincident with rapid climate warming that dates from the 1980's and has been associated with longer ice-free periods and activation of multiple sediment supply sources from the deglaciated landscape. In colder phases of post-LIA period, coastal zone development was subdued and strongly dependent on the efficiency of sediment transport via in a longshore drift. Finally, we discuss the differences in the post-LIA coastal responses between central Spitsbergen and western Spitsbergen highlighting the efficiency of paraglacial sediment delivery from land to the coast controlled by the state of glacial systems, bedrock topography and development of river channels.
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    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
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    Glyphosate and AMPA concentrations in wind-blown material under field conditions. (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-06
    Description: Agricultural intensification in fragile arid and semi-arid environments has led to an increase in soil degradation, mainly through wind erosion. Argentina is an agricultural and cattle-farming country, which has increased its productivity in the last few decades, widening the boundaries of farm land and the use of herbicides to control weeds. Glyphosate, which accounts for 65% of the Argentinian pesticides market, is strongly retained in soil. The World Health Organization concluded that there was evidence to classify glyphosate as 'probably carcinogenic to humans'. In this context, the objective of this study was to determine the presence and concentration of glyphosate and aminomethylphosphonic acid (AMPA) in wind-blown material in three areas in Argentine semi-arid regions (Chaco, CH; La Pampa, LP and San Luis, SL). In one hectare (ha) squared plots, left uncovered and levelled, the wind-blown material was collected at heights of 13.5, 50 and 150 cm during 18 erosion events. The wind-blown material carried by the wind at a height of 150 cm had concentrations of 247μg kg -1 and 218μg kg -1 of glyphosate and AMPA, respectively.This material was enriched 60 times in glyphosate and 3 times in AMPA as compared to the original soil. This shows that the eroded material can, potentially, have a negative impact on the ecosystem and also on human health, depending on the proportion of this material released into the atmosphere in suspension as particulate matter. This study is, to our knowledge, the first to report concentrations of glyphosate and AMPA in wind-blown material under field conditions.
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    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
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    THE IMPACT OF CULTIVATED LAND SPATIAL SHIFT ON FOOD CROP PRODUCTION IN CHINA, 1990-2010 (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-06
    Description: Cultivated land has been undergoing significant spatial shift during the last two decades in China, according to land-use data derived from the Landsat Thematic Mapper. Based on soil organic matter data and yield data at county level, we developed a constant crop yield dataset at pixel level with a resolution of 1 km. Using this dataset, this paper quantitatively evaluates average crop yield change due to cultivated land spatial shift at national and regional levels. The results show: 1) at national level, the average crop yield per unit area decreased by 1.99% during the period 1990–2010. The main reason for this is that built-up areas occupied a significant amount of high-yield cultivated land while low-yield land was converted in ecologically vulnerable areas. 2) In spite of 7.72 million ha cultivated land was converted to built-up areas, especially in areas with high economic value, such as Huang–Huai–Hai Plain, 32.94 million ha land was converted to cultivated land, especially in Northeastern and Northwestern China. 3) The quality gap between cultivated land converted to built-up areas (CLCBA) nationally and new cultivated land regionally suggests that the loss of 1 ha of CLCBA would, to achieve equivalency, need to be compensated by 1.54 ha of new land in Xinjiang, or more in Northeastern China. However, cultivated land expansion in these areas may cause land degradation and a series of ecological environment problems.
    Print ISSN: 1085-3278
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    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
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    DRY-STONE WALL TERRACE MONITORING AND MODELING (2018)
    Wiley-Blackwell
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    Publication Date: 2018-03-06
    Description: Dry-stone wall agricultural terraces are widespread all over the world, and represent an effective retaining structure for farming purposes. However, dry-stone walls can be subjected to degradation and damages, with complex and expensive maintenance. Such high costs are the most relevant drivers of land abandonment in many agricultural areas of Europe and of other continents, resulting in a progressive loss of cultivable surface, cultural heritages and landscape traditional elements. Therefore, a more effective and efficient management of these systems is needed. As a contribution, in the present paper an innovative modelling approach system is proposed. The presented model is able to describe hydrological processes on a terraced slope, and to analyze the destabilizing pressures acting on the retaining dry-stone walls in the most critical portion of each terrace. The model structure is based on the results of multidisciplinary field monitoring campaigns on water circulation in terraced landscapes carried out on a terraced vineyard (Lamole, Tuscany, Italy). A monitoring station was set up on a recently reconstructed dry-stone wall, to measure the parameters influencing the pressures acting on the retaining structure. The results show a good capability of the model to predict the distribution and intensity of stresses on the instrumented dry-stone wall over time ad space. Such stresses were related to the earth pressure and to hydrostatic pressures (water accumulation), without the occurrence of soil saturation. Detecting the most failure-prone portions of a terraced system, this approach can support landowners and land planners in manage these complex and fragile environments.
    Print ISSN: 1085-3278
    Electronic ISSN: 1099-145X
    Topics: Geography , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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