Soil Degradation Index Research Articles

Soil degradation around Orji municipal solid waste dump site: a spatial assessment.

The present study assessed the impact of municipal solid waste dump on the degradation of soil around Orji dump site. A total of 15 soil samples were collected for this study. Twelve soil samples were collected around the dump site at 0m, 10m, and 20m distance and three from Imo State University (IMSU) research farm as control. The samples were collected from the east, west, north, and south of the dump site. The samples were subjected to laboratory analyses. The mean results obtained indicate that the values of the dump site soil parameters analyzed ranged from 86.67 to 89.00% (sand), 4.33 to 5.67% (silt), 7.00 to 7.67% (clay), 6.80 to 7.50 (pH), 4.33 to 7.00 dS m-1 electric conductivity (EC), 0.0028 to 0.0045mgkg-1 (salinity), 2.36 to 3.76% soil organic matter (SOM), 24.13 to 38.93 cmolc kg-1 cation exchange capacity (CEC), 4.50 to 9.57 cmolc kg-1 calcium (Ca), and 1.0 to 2.25 cmolc kg-1 magnesium (Mg). At the control, mean values were 81.24% (sand), 6.39% (silt), 12.45% (clay), 5.69 (pH), 0.47 dS m-1 (EC), 0.0005mgkg-1 (salinity), 1.99% (SOM), 5.08 cmolc kg-1 (CEC), 2.17 cmolc kg-1 (Ca), and 1.67 cmolc kg-1 (Mg). These values showed substantial enrichment. Correlations indicate that EC, salinity, and CEC majorly determined the availability of most of the parameters analyzed. Soil degradation index (SDI) was used to determine degradation around the dump site. It ranged from 2.546.61% (0m) to 1573.50% (10m) and 1.603.73% (20m). Thus, distance affected the rate of soil degradation in all directions away from the dump site.

Response of soil quality degradation to cultivation and soil erosion: A case study in a Mollisol region of Northeast China

Soil degradation is endangering agricultural and ecological sustainability in the Mollisol region of Northeast China. Cultivation and soil erosion are the primary drivers degrading soil quality. However, few studies have comprehensively quantified the effects of cultivation and soil erosion on soil quality degradation in Mollisols. Therefore, three sampling sites with similar landscapes, erosion environments and agricultural management practices were selected. The cultivation chronosequence was determined using a space-for-time substitution approach, including 1) forestland without cultivation (0 yr, stage I), 2) farmland with few cultivation years (< 20 yr, stage II), and 3) farmland with many cultivation years (> 80 yr, stage III). Soil erosion was quantified using the caesium-137 (137Cs) and black soil thickness. Sixteen soil physicochemical indicators were analyzed, and soil quality and its degradation were evaluated using an integrated soil quality index (SQI) and a soil degradation index (SDI), respectively. The results showed that soil erosion was profoundly accelerated by cultivation. Soil organic carbon (SOC), bulk density (BD), mean weight diameter (MWD) and soil erodibility (K) factor were selected to develop the SQI. The SQI was higher in stage I (0.61±0.05) than in stages II (0.49±0.06) and III (0.52±0.03) and decreased with increasing soil erosion rate, implying that cultivation and soil erosion exacerbated the degradation of soil quality. Furthermore, cultivation and soil erosion contributed 16.0–51.1% and 2.0–18.4% to the changes in soil quality, respectively, and their combination further amplified the impacts (8.4–61.5%). Cultivation and accelerated soil erosion driven by cultivation led to the degradation of soil quality; the former controlled the degradation processes mainly by decreasing the MWD, and the latter induced soil quality degradation by reducing the SOC and increasing the K factor. These findings are important for advancing our understanding of the driving forces and mechanisms of soil degradation in the Mollisol region.

Quantitative analysis of soil degradation in response to land use change in the Guinea savanna zone of Ghana

Soil degradation (SD) poses a significant challenge to tropical agricultural production systems due to its role in depleting soil nutrients. Recently, SD has threatened population growth by causing hunger and poverty among smallholder farmers in the Guinea savanna agro-ecological zone of Ghana. However, SD cannot be directly measured. Instead, assessment and modelling efforts rely on biological and physico-chemical indicators. This study sought to: (i) select a minimum dataset (MDS) using a multivariate statistical technique; (ii) identify SD processes, and evaluate the extent of degradation; and (iii) suggest strategies to monitor SD in the study area. Soil samples were collected using the Land Degradation Surveillance Framework (LDSF), specifically designed for sub-plot level (1000 m2) sampling. This scheme aligns well with the typical farm structure of smallholder farmers (<10 acres). Soil samples, taken from a depth of 0–20 cm, were analyzed to assess their physico-chemical properties. Principal component analysis (PCA) identified seven key SD processes: soil texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (Av. P), base saturation (BS) and Effective Cation Exchange Capacity (ECEC). These identified processes lead to the loss of OC, deterioration of soil texture, reduction in soil nutrients, and increased soil acidity. There was a strong positive correlation (r = 0.70, p<0.05) between soil physical and chemical properties. PC1 explained 26.86% of the total variance, followed by PC2 at 15.31%, PC3 at 12.46%, and PC4 at 9.98%. Also, PC5, PC6, and PC7 accounted for 8.49%, 7.25% and 1.42% of the variance, respectively. The land-use systems we identified significantly affected the concentration of soil nutrients (p<0.001). In our computed Composite Soil Degradation Index (CSDI), CEC emerged as the most significant SD indicator with a weight of 0.328, followed by Si:CL ratio at 0.187. The results indicate that soil management activities should focus on increasing organic matter. Soil nutrient depletion primarily occurs through several processes. Land clearing and burning of organic materials during land preparation are primary causes. Furthermore, a total crop removal during harvest, inadequate manure application, and subsequent leaching and erosion aggravates SD, leading to nutrient-depleted soils. We conclude that the loss of nutrients, specifically CEC, OC, Ex. K and Av. P is the primary contributor to chemical SD. Therefore, implementing integrated soil fertility management (ISFM) strategies, such as applying organic (e.g., animal-based manures, green manure, crop residues, compost) and inorganic fertilizers (e.g., NPK + micronutrients) is crucial for increasing soil nutrient availability, enhancing SOM content, and promoting carbon sequestration in these farming systems. This study establishes a baseline for comparing and evaluating the effectiveness of land management interventions at the landscape level in northern Ghana. Consequently, soil nutrient management should be tailored to site-specific conditions, focusing on increasing the efficiency of N, P, K and micronutrient uptake by plants. Adopting such site-specific management strategies could significantly contribute to the sustainable intensification of agricultural production systems in the Guinea Savanna agro-ecological zone of Ghana.

Soil degradation detected by temporal satellite image in São Paulo state, Brazil

Soil degradation is a major challenge in the 21st Century. Tropical regions are having the strongest expansion in agricultural lands. Therefore, novel researches on the soil degradation process are imperative to prevent damage to social and environmental dynamics. The main goal of this research was to generate a Soil Degradation Index in a tropical region that includes the entire agricultural areas of the São Paulo State, Brazil, making use of the factors that can be directly related to it as different environmental indicators. The determination of the areas with exposed soil, based on Landsat time series data (1985–2019), was processed with the Geospatial Soil Sensing System methodology. Additionally, thematic maps of clay, cation exchange capacity and organic matter were generated from the calibration of pixels of Landsat images, taking into account surface soil samples (0–20 cm). The spatialization was performed using a random forest algorithm. The average precipitation was obtained for the period of analysis, using the CHIRPS dataset to generate the historical mean information about the years of study. The surface temperature was determined based on the Landsat 5 and 8 thermal bands. Using the elevation model, other terrain data were obtained, such as LS factor and Slope. The land use information was acquired from the Mapbiomas platform and reclassified into five categories of use. The k-means clustering algorithm was used to generate the Soil Degradation Index (SDI), which classified the values of the variables into five degradation categories: from 1, very low, to 5, very high. The model was validated using the OM information. There was an important relationship between the SDI and the spectral surface reflectance obtained by Landsat. Locations with less OM presented a higher degradation level. Integrating multitemporal remote sensing data and environmental variables proved to be effective to assist the SDI, which can monitor and improve the land use decision-making and public policies, in order to prevent economic and environmental issues.

Assessing degradation of lake wetlands in Bashang Plateau, China based on long-term time series Landsat images using wetland degradation index

Continuous monitoring of wetland dynamics and regional-scale assessment of wetland degradation are important to understand wetland ecosystem processes and to formulate restoration measures. The lake wetlands in Bashang Plateau play vital roles in providing essential resources and maintaining biodiversity in North China, while they were not fully investigated in previous studies. In addition, previous studies on wetland degradation assessment mostly relied on wetland area change every five or ten years. Continuous dynamics of wetlands was rarely considered. In this study, we developed a new wetland degradation index (WDI) to assess lake wetland degradation in Bashang Plateau based on time series Landsat imagery from 1985 to 2020 on Google Earth Engine platform. WDI integrates three indicators, namely lake shrinkage index (LSI), vegetation degradation index (VDI) and soil degradation index (SDI), which represents hydrodynamics of wetland inundation, vegetation, and soil conditions of wetlands, respectively. Different from previous research that utilized remotely sensed image to extract wetland every five or ten years, the LSI considers time-series continuous dynamics of lake water inundations and the transitions between water and non-water on a pixel-by-pixel basis. Our results showed that small lake wetlands with area less than 8 ha are dominant in Bashang Plateau. Both the number and the area of lake wetlands showed large interannual variations. The number (area) of lake wetlands reached 1715 (31,419 ha) in 1995–1996 and were only 493 (7,717 ha) in 2009–2010. The total area of the lake wetlands in 2019–2020 was only around 1/3 of that in 1995–1996. The LSI, VDI, SDI, as well as WDI demonstrate large spatial variations among the lake wetlands and within the lake wetlands. Wetlands in the western and central subregions experienced more severe degradation than those in the eastern subregion, and the edge of the wetlands normally showed more severe degradation. The resulted degradation grades are consistent with our field investigations. Among the 11 counties in Bashang Plateau, Zhangbei (ZB) county in the western subregion has the largest area with severe and very severe degradation grades. Degradation of lake wetlands was mainly associated with groundwater level declination which was induced by anthropogenic activities and economic development. The proposed WDI in this study can be widely applicable for regional-scale wetland degradation assessment using remote sensing techniques and thus further help decision making in lake wetland conservation and restoration.

Soil Erosion Susceptibility Prediction in Railway Corridors Using RUSLE, Soil Degradation Index and the New Normalized Difference Railway Erosivity Index (NDReLI)

This study presents a remote sensing-based index for the prediction of soil erosion susceptibility within railway corridors. The empirically derived index, Normalized Difference Railway Erosivity Index (NDReLI), is based on the Landsat-8 SWIR spectral reflectances and takes into account the bare soil and vegetation reflectances especially in semi-arid environments. For the case study of the Botswana Railway Corridor (BRC), the NDReLI results are compared with the RUSLE and the Soil Degradation Index (SDI). The RUSLE model showed that within the BRC, the mean annual soil loss index was at 0.139 ton ha−1 year−1, and only about 1% of the corridor area is susceptible to high (1.423–3.053 ton ha−1 year−1) and very high (3.053–5.854 ton ha−1 year−1) soil loss, while SDI estimated 19.4% of the railway corridor as vulnerable to soil degradation. NDReLI results based on SWIR1 (1.57–1.65 μm) predicted the most vulnerable areas, with a very high erosivity index (0.36–0.95), while SWIR2 (2.11–2.29 μm) predicted the same regions at a high erosivity index (0.13–0.36). From empirical validation using previous soil erosion events within the BRC, the proposed NDReLI performed better than the RUSLE and SDI models in the prediction of the spatial locations and extents of susceptibility to soil erosion within the BRC.

Spatial distribution of soil morphology and physicochemical properties to assess land degradation under different NDVI and TRI in North Halmahera, Indonesia

Land degradation is currently a major environmental problem that can lead to decreasing biomass productivity. The causes of land degradation have been widely reported. However, the soil morphological characteristics and its detailed properties related to land degradation need to be investigated further. The research was conducted in North Halmahera Regency in March-April 2020. The study started with an overlay of basic maps such as rainfall, land use, topography, and soil types to map the degraded land units. Several land units classified from slightly damaged to severely damaged will be validated based on field observations and supported by laboratory measurements. Characterization of soil morphology and soil sampling was carried out according to USDA international standards. Sentinel 2A image and SRTM image from March to April 2020 were used to determine NDVI and TRI. The characteristics of the soils that have not been degraded tend to be found in volcanic landscapes, while those of the degraded soils tend to be found in structural and karst hills. The thickness of the degraded soil horizons tends to be shallower with an incomplete horizon arrangement, and many rock fragments are found in the soil surface layer. SOC gradually decreases in degraded soils, while the essential nutrients (N, P, and K) are relatively more varied across soil types. The improper land use without conservation on steep slopes causes the soils to be easily degraded. The soil degradation index has a linear relationship with NDVI and TRI. Thus, the revitalization of degraded lands needs to pay attention to the layout and types of vegetation with different slope levels according to the geomorphological zone.

Assessment of earthworms as an indicator of soil degradation: A case‐study on loess soils

AbstractSoil degradation restricts the development of agriculture, and the degree of soil degradation is related to land use type, and efficient evaluation methods are helpful for the timely implementation of remedial measures to ensure soil sustainability. Earthworms are directly affected by the deterioration of soil properties during the degradation process. The feasibility of using earthworms to assess soil degradation, however, still needs to be verified. In our Loess Plateau study, earthworm biomass, density, and diversity (Shannon‐Wiener, species richness, and Pielou's evenness) were investigated under nine different land use types (natural woodland, shrubland and grassland; planted woodland, shrubland and grassland; and cropland, orchard, abandoned land) and we analyzed their relationships with soil degradation. Our results showed earthworm biomass, density, and diversity associated with a low degree of degradation were significantly higher than those associated with a high degree of degradation. Earthworms can comprehensively characterize the physicochemical properties and biological characteristics of soils under different land use types. Linear correlations showed a significant relationship between the soil degradation index and the earthworm indices, indicating that the latter could be used to effectively evaluate and represent the degree of degradation of soils on the Loess Plateau over a certain degradation range. Nevertheless, this evaluation method requires further validation before wider use.

Spatio-temporal changes in habitat quality and linkage with landscape characteristics in the Beressa watershed, Blue Nile basin of Ethiopian highlands

An increase in human population generally exerts pressure on natural habitats and leads to a decline in biodiversity resources. As a proxy for biodiversity study, an evaluation of habitat quality (HQ) change caused by land use/land cover (LULC) and associated landscape structural changes may provide a scientific basis for ecological protection and landscape management. This study analyzed spatio-temporal changes in HQ over the last four decades and predicted the trends over the next three decades. The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model was employed to evaluate the state of HQ. Criteria of habitat naturalness, habitat complexity and a soil degradation index were used to classify habitat types. Results showed that, between 1972 and 2017, areas with high HQ indicators declined by about 20% while areas with poor HQ increased by 11%. An unprecedented expansion of anthropogenic LULC changes related to the growth of human settlements and artificial plantations and a decline in natural and semi-natural habitats resulted in the total loss of HQ by about 35%. The mean value of HQ decreased from 0.60 to 0.45 during the study period. The distribution of moderate levels of HQ, primarily in farmlands, remained essentially unchanged. Predicted HQ values are expected to follow a similar trend to past decades with 41.5% of the areas continuing to decline, although with a slight HQ improvement in some areas. The spatial distribution of HQ is negatively correlated with habitat degradation (R2 = 0.95 at p < 0.01) and slope (R2 = 0.84 at p < 0.05). HQ change also appears more strongly influenced by landscape composition than by configuration in the watershed. The most important landscape structure variables accounted for HQ change were LPI, PLAND and MPS of anthropogenic habitats, suggesting reducing habitat modifications and restoring degraded natural habitats is crucial to maintain biodiversity in the study area.

Sustaining Rice Productivity, Soil Fertility, and Income from Prawn-Rice Joint Culture in the Gher System in Banglade

This paper examines the long-term impacts of the joint prawn-rice gher farming system on agricultural and household incomes, soil fertility, and productivity of modern variety (MV) rice in southwestern Bangladesh, based on socioeconomic data of the gher farmers and soil fertility data of their gher plots. In 2005, 20 farmers operating on 30 plots were randomly selected from the Bilpabla village of Khulna from whom prawn and MV rice production data were collected using a questionnaire; soil samples were also collected and tested. In 2011 and 2017, the sustainability of the gher system over time was assessed through another survey of farmers following the same methodology. Results revealed that although the nominal income from gher farming increased by 59 percent in 2011 and 23 percent in 2017, the real income and per capita household income remained unchanged over time. Agricultural income has contributed about 65 percent to household income, which for gher farmers was about 200 percent higher than average rural incomes in Bangladesh. Rice productivity declined slightly from its 2005 level. However, the productivity of MV rice under prawn-rice gher farming is substantially higher than in the conventional MV rice farming system. The positive estimates of the Mean Soil Quality Index and Soil Degradation Index for land used for MV paddy production within the gher indicate an increase in soil nutrients. This suggests that the joint prawn-rice gher farming system is relatively sustainable, having improved soil fertility and stabilized real income. Policy implications toward promoting agricultural growth in the southwestern region of Bangladesh include research on developing varieties of MV rice suited to prawn-rice gher farming and the development of commercial feeds and markets for prawn to further raise productivity and incomes of gher farmers.

Soil degradation index developed by multitemporal remote sensing images, climate variables, terrain and soil atributes

Studies on soil degradation are essential for environmental preservation. Since almost 30% of the global soils are degraded, it is important to study and map them for improving their management and use. We aimed to obtain a Soil Degradation Index (SDI) based on multi-temporal satellite images associated with climate variables, land use, terrain and soil attributes. The study was conducted in a 2598 km2 area in São Paulo State, Brazil, where 1562 soil samples (0–20 cm) were collected and analyzed by conventional methods. Spatial predictions of soil attributes such as clay, cation exchange capacity (CEC) and soil organic matter (OM) were performed using machine learning algorithms. A collection of 35-year Landsat images was used to obtain a multi-temporal bare soil image, whose spectral bands were used as soil attributes predictors. The maps of clay, CEC, climate variables, terrain attributes and land use were overlaid and the K-means clustering algorithm was applied to obtain five groups, which represented levels of soil degradation (classes from 1 to 5 representing very low to very high soil degradation). The SDI was validated using the predicted map of OM. The highest degradation level obtained in 15% of the area had the lowest OM content. Levels 1 and 4 of SDI were the most representative covering 24% and 23% of the area, respectively. Therefore, satellite images combined with environmental information significantly contributed to the SDI development, which supports decision-making on land use planning and management.

Hyper-spectral response and estimation model of soil degradation in Kenli County, the Yellow River Delta.

The ecological environment of the Yellow River Delta is fragile, and the soil degradation in the region is serious. Therefore it is important to discern the status of the soil degradation in a timely manner for soil conservation and utilization. The study area of this study was Kenli County in the Yellow River Delta of China. First, physical and chemical data of the soil were obtained by field investigations and soil sample analyses, and the hyper-spectra of air-dried soil samples were obtained via spectrometer. Then, the soil degradation index (SDI) was constructed by the key indicators of soil degradation, including pH, SSC, OM, AN, AP, AK, and soil texture. Next, according to a cluster analysis, soil degradation was divided into the following three grades: light degradation, moderate degradation, and heavy degradation. Moreover, the spectral characteristics of soil degradation were analyzed, and an estimation model of SDI was established by multiple stepwise regression. The results showed that the overall level of reflectance spectra increased with increased degree of soil degradation, that both derivative transformation and waveband reorganization could enhance the spectral information of soil degradation, and that the correlation between SDI and the spectral parameter of (Rλ2+Rλ1)/(Rλ2-Rλ1) was the highest among all the spectral parameters studied. On this basis, the optimum estimation model of SDI was established with the correlation coefficient of 0.811. This study fully embodies the potential of hyper-spectral technology in the study of soil degradation and provides a technical reference for the rapid extraction of information from soil degradation. Additionally, the study area is typical and representative, and thus can indirectly reflect the soil degradation situation of the whole Yellow River Delta.

Land conversion effect on the dynamics of selected soil physicochemical properties in a tropical environment of southern Kerala

Different types of land uses have a profound impact on various soil quality parameters. Determining the changes in soil quality resulting from land use change is essential to design sustainable land management plans and policies. The present study is an attempt to evaluate the effect of land conversion on soil degradation in a tropical environment of Kerala, India. The study involves 28 soil samples from six representative land uses viz., forest, forest plantations, rice, settlement with mixed trees (SMT), clay mining sites and urban areas. Soil physicochemical parameters like bulk density, particle density, electrical conductivity, porosity, water holding capacity, pH, soil organic carbon, cation exchange capacity, phosphorus, potassium and magnesium were considered. Standard deviation and coefficient of variation were used to find out the statistical significant differences in soil quality parameters among land uses under study. A simple soil degradation index was employed to identify the nature of soil degradation. Results showed that extensive land conversion occurred in the study area with urbanization as the major driving force. Soil degradation index showed that soil degradation was higher in the clay mining areas, urban and rice soils.

Changes in surface soil properties and macroinvertebrate communities with the conversion of secondary forests to oil palm (Elaeis guineensis) plantations

The conversion of natural forest to oil palm (Elaeis guineensis Jacq.) plantation is perceived as a threat to biodiversity conservation. The aims of this investigation were to assess variation in soil physico-chemical parameters and macroinvertebrate structures following the conversion of secondary forests to oil palm plantations, and to understand what to expect with the aging of the plantations. We hypothesised that soil properties would be improved with respect to biodiversity conservation with the aging of the oil palm plantations. Sampling was carried out in secondary forests, and in 13-, 20- and 39-year-old oil palm plantations at the La Mé Station, Côte d’Ivoire. Three sampling areas were established in each land-use type and age class, for a total of 12 sampling areas. Over a 50-m transect, litter-dwelling macroinvertebrates were sampled by using pitfall traps, and topsoil (0–10 cm) macroinvertebrates by using monoliths (50 cm by 50 cm by 10 cm), following the modified ‘Tropical soil biology and fertility’ method. Soil physical and chemical parameters were characterised. The results showed that the conversion of secondary forests to oil palm plantations was characterised by changes in soil macroinvertebrate density (–30%), taxonomic richness (–37%) and functional groups (–17%), as well as soil bulk density (+14%) and water content (+16%), after ~39 years of conversion. Soil organic carbon, total nitrogen and organic matter increased with the aging of plantations, and reached conditions similar to those of secondary forests. The human interference imposed on macroinvertebrate communities during site preparation and planting was not compensated by the reduction in the soil-degradation index over time. The results have implications for implementation of conservation agriculture and the related management practices.

Effects of land cover changes and slope gradient on soil quality in the Gumara watershed, Lake Tana basin of North\u2013West Ethiopia

This study evaluated land cover change and slope gradient on selected soil quality parameters in the Gumara watershed, northwestern Ethiopia. 36 soil samples were collected from 0- to 20-cm depth under four land cover types across three slope gradients. The collected soil samples were analyzed for selected soil quality parameters. Result indicated that the bulk density of the soil is different (P < 0.001) in the watershed because of land cover change and slope gradient. Cultivated land and steeper slopes have the highest bulk density and lowest total porosity. On the other hand, the forestland and gentler slopes have lowest bulk density and high total porosity. Intensive cultivation accompanied by continuous conversion of forestland to cultivated land caused high bulk density and low total porosity. Cation exchange capacity, exchangeable magnesium total nitrogen, available phosphorus and potassium negatively correlated with slope gradient. Conversion of forestland to cultivated land contributed to changes in pH (P < 0.05) exchangeable calcium (P < 0.01), potassium (P < 0.001), available phosphorus (P < 0.01) and nitrogen (P < 0.01) content. The soil degradation index results showed that soil organic carbon, nitrogen, available phosphorus and exchangeable potassium contents declined and bulk density increased because of the land cover change. This negative effect on agricultural development and environmental health of the watershed makes an integrated land resource management approach vital for sustaining agricultural productivity and the environment health of the Gumara watershed.

Abundance and diversity of soil mite (Acari) communities after conversion of tropical secondary forest into rubber plantations in Grand‐Lahou, Côte d'Ivoire

AbstractThe objective of this investigation was to understand the modification of mite communities and soil physico‐chemical parameters after conversion of secondary forests into rubber plantations and how these change with the aging of the plantations. The sampling was performed in a humid period and samples were taken from three of each age of secondary forests, 7‐year‐old rubber plantations, 12‐year‐old rubber plantations and 25‐year‐old rubber plantations. We hypothesized that the stress imposed on mite communities during site preparation and planting would be compensated for by the reduction of the soil degradation index as the rubber plantations age. Across the 12 sampling areas, 120 soil cores were taken at 10 cm soil depth over a 40 m transect. Soil physico‐chemical parameters were characterized and soil mites were extracted with a modified Berlese‐Tullgren funnel over the course of 10 days. The results showed that conversion of secondary forests into rubber plantations leads to a modification in the density of mites (−60 and +1%), species richness (−48 and −15%), water content (−62 and −31%), soil organic carbon (−67 and −51%) and total nitrogen (−64 and −52%) respectively after about 7 and 25 years of conversion. The investigation pointed out an improvement in soil ecological quality with the aging of rubber plantations over time and this was characterized by an increase in the density of mites (+150%), species richness (+63%), water content (+84%), organic carbon (+50%) and total nitrogen (+33%) in the 25‐year‐old plantations compared to the 7‐year‐old plantations.

若尔盖沙化草地恢复过程中土壤特性及水源涵养功能

PDF HTML阅读 XML下载 导出引用 引用提醒 若尔盖沙化草地恢复过程中土壤特性及水源涵养功能 DOI: 10.5846/stxb201607221492 作者: 作者单位: 福州大学环境与资源学院,四川农业大学农学院,福州大学环境与资源学院,福建师范大学地理科学学院;福建师范大学地理科学学院,中国科学院山地灾害与环境研究所,四川农业大学农学院,若尔盖县林业局 作者简介: 通讯作者: 中图分类号: 基金项目: 美国国家地理科研基金资助项目（9336-13）；国家自然科学基金资助项目（41401313）；四川省教育厅自然科学重点项目资助项目（12ZA273）；福州大学人才基金（510211） Changes in water conservation and soil physicochemical properties during the recovery of desertified grassland in Zoigê, China Author: Affiliation: College of Environment and Resources,Fuzhou University;China;,College of Agronomy,Sichuan Agricultural University,College of Environment and Resources,Fuzhou University,College of Geographical Sciences,Fujian Normal University,Institute of Mountain Hazards and Environment, Chinese Academy of Sciences,College of Agronomy,Sichuan Agricultural University,Forestry Bureau of Zoigê County Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:1995年以来，政府大力开展对若尔盖沙化草地生态系统的恢复重建工作，其生态恢复效益受到广泛关注。而水源涵养功能作为衡量草地生态系统恢复程度的重要生态指标，其变化对水分循环及全球气候变化有一定的影响和响应。以若尔盖县不同治理年限的沙化草地治理区为研究对象（包括1995年、2007年、2009年、2010年、2011年的治理区，2012年的正常放牧区和2012年的无治理区），采用野外采样和室内分析相结合的方法，将土壤含水量作为研究指标，结合土壤的理化性质，分析沙化草地在恢复重建过程中水源涵养功能的变化及其影响因素，结果表明：若尔盖草地在恢复重建过程中，（1）土壤质地发生变化，由紧砂土逐渐恢复成砂壤土，保水能力及保肥性都得到显著提高；土壤容重随着治理时间的增加而降低，由无治理区的1.7 g/cm3下降到正常放牧区的1.3 g/cm3；（2）土壤pH值随着治理时间的增加而逐渐降低，由7.6逐渐下降到6.7，土壤总体上为中性土，适宜植被生长；土壤有机质的变化相对不明显，但治理区的有机质远低于正常放牧区的土壤有机质，总体呈缓慢上升趋势；（3）土壤含水量呈“V”型变化趋势，在治理初期，土壤含水量先减小，2009年治理区的含水量最低，仅为6.8%，但到了治理后期，土壤的含水量开始增加，1995年的沙化治理区含水量达到了12.1%，说明水源涵养能力得到相应的提升；（4）经过相关分析，土壤含水量和有机质、土壤质地、土壤pH值、生物量以及土壤碳含量呈显著相关关系，其中，含水量与有机质、土壤质地以及土壤碳含量呈极显著正相关，而与pH值呈显著负相关；（5）随着治理时间的增加，土壤退化指数逐渐减小，土壤状况得到不断的改善。 Abstract:The restoration and reconstruction of desertified grassland has been continually initiated by the central government of China since 1995, and the ecological benefits of grassland restoration gained attention both home and abroad. In particular, the water conservation function of grassland is regarded as the primary indicator of the ecosystem's restoration and is one of the most important grassland ecosystem services. Changes in water conservation are related to the water cycle and global climate change. The present study investigates the moisture and physicochemical properties of desertified grassland soil over several years (managed sample plot in 1995, 2007, 2009, 2010, and 2011; non-managed sample plot in 2012; and normal grazing area in 2012) in Zoigê County, using both field investigation and experiments to analyze the dynamics of water conservation and its determinants. During the recovery process, 1) Soil texture had changed that tight sandy soil was gradually converted to sandy loam, water conservation and fertilizer preservation capacity were increased, and bulk soil density decreased from 1.7 g/cm3 in the non-managed area to 1.3 g/cm3 in the normal grazing area. 2) Soil pH value decreased from 7.6 to 6.7 with the duration of management, and according to the classification of soil pH, the soil was neutral soil which was suitable for vegetation growth. Meanwhile, soil organic matter of the treatment areas was far lower than that of the normal grazing area, although the organic matter exhibited an upward trend. 3) Soil moisture exhibited a V-shaped trend that the content decreased in the early stage of management and the content of managed area in 2009 was lowest for only 6.8%. But in the late stage of management, the content increased from 6.8% to 12.1% in the managed area in 1995, in which the grassland had been restored and water conservation got improvement. 4) Correlation analysis indicated that soil moisture was significantly correlated with organic matter content, soil texture, pH, biomass, and soil carbon content, although the relationship between soil moisture and pH was negative. 5) As the duration of treatment increased, the soil degradation index decreased, and the soil conditions improved greatly. 参考文献 相似文献 引证文献

Impact of land cover changes and topography on soil quality in the Kasso catchment, Bale Mountains of southeastern Ethiopia

This study assessed land cover change and topographic elevation on selected soil quality parameters in the Kasso catchment, southeastern Ethiopia. Twenty‐seven soil samples collected from 0–30cm depth under four land cover types across three elevation gradients were analysed for selected soil quality parameters. Results indicated that soil particle size distribution is different (p&lt;0.001) in the catchment because of the effect of land cover change and elevation. Most cultivated lands occupy lower elevations where clay accumulates as a result of its movement from higher to lower elevations. Ploughing accentuates weathering, making cultivated lands richer in finer materials. Cation exchange capacity and exchangeable magnesium and potassium negatively correlated with elevation, total nitrogen and available phosphorous. Conversion of natural vegetation to cropland contributed to changes in pH (p&lt;0.05), exchangeable calcium (p&lt;0.01), potassium (p&lt;0.001), available phosphorous (p&lt;0.01) and nitrogen (p&lt;0.01) contents. Parameter soil degradation index results showed that soil organic carbon, nitrogen, available phosphorous and exchangeable potassium contents declined and bulk density increased because of the land cover change. This negative effect on agricultural development and environmental health of the catchment makes an integrated land resource management approach indispensable for sustaining agricultural productivity and the environmental health of the Kasso catchment.

Using Cesium-137 to investigate soil quality under conservation tillage on steep lands

Few studies have demonstrated the long-term effects of different tillage practices on changes of soil quality; however, understanding such effects is vital for the selection and establishment of appropriate soil conservation measures on steep hillslopes. This study was conducted at two adjacent sites in the Sichuan Basin, China, with one cultivated by traditional tillage (TT; i.e., hoeing starts at the bottom position and soil is moved downslope because of gravity and drag) and the other cultivated by conservation tillage (CT; i.e., hoeing is performed from hilltop to bottom, but soil is moved uphill because of drag). We used the Cesium-137 (¹³⁷Cs) tracer technique to identify the pattern of soil constituent distribution and soil quality differences between the two tillage practices. The ¹³⁷Cs residual rate for the CT practice ranged from −29.44% to 34.16% with an average of −8.56%, and the TT practice ranged from −57.12% to 4.63% with an average of −29.49%. A greater increase (ranging from 18.43% to 50.69%) in soil constituents (i.e., soil organic matter, total nitrogen [N], phosphorus [P], and potassium [K], available N, and extractable P and K) was found in the CT soils than in the TT soils. The CT treatment site exhibited markedly higher concentrations of soil constituents in each soil depth profile (0 to 40 cm [0 to 15.7 in] and each 5 cm [2 in] in length increment). The soil degradation index (SDI) for the CT practice significantly increased compared to the TT practice in the 0 to 15 cm (0 to 5.9 in) and 15 to 40 cm (5.9 to 15.7 in) depth of the profiles (<i>p</i> &lt; 0.05). The greatest difference in SDI induced by these two tillage practices occurred at the summit and toeslope positions, with an increase in SDI of 28.07% and 15.76% in the 0 to 15 cm (0 to 5.9 in) depth and of 49.16% and 31% in the 15 to 40 cm (5.9 to 15.7 in) depth, respectively. The ¹³⁷Cs residual rate showed a corresponding relationship with the SDI changing trend, which implied that the ¹³⁷Cs residual rate may be considered an indicator for appraising soil quality for eroding hillslopes. It is suggested that the long-term practice of CT largely diminishes soil degradation because of upslope soil translocation; therefore, it would also significantly improve soil quality in steeply sloping fields.

Soil degradation associated with water-level fluctuations in the Manwan Reservoir, Lancang River Basin

This study was conducted to understand the impacts of dam-induced water-level fluctuations (WLFs) on soil properties. The redundancy analysis (RDA) and two soil degradation indices were used to analyse soil degradation under different land uses and at different soil depths. In addition, the relationships among soil degradation and topographical and geographical parameters were determined. The sampling sites were located in two zones along the Manwan Reservoir, which is a section of the Lancang River in Southwestern China. These zones included a water-level-fluctuation zone (WLFZ) and an infralittoral reference zone (IRZ), which included forestlands, scrublands, and farmlands. The results indicated that WLFs increased soil pH, total phosphorus (TP) concentrations, and total potassium (TK) concentrations, and decreased soil total carbon (TC) and total nitrogen (TN) concentrations. Meanwhile, the WLFs increased the soil C/N ratio, which indicated that the WLFs had a stronger effect on TN than on TC. The degree of soil degradation based on the soil degradation index and the changes in the soil quality index indicated that WLFs significantly affected topsoil quality (0–5cm), especially in the scrubland, which had the highest degradation level. The results from the RDA indicated that soil degradation significantly increased with decreasing distance along the river upstream of the dam (P<0.05; F=3.05). Our results identified soil degradation in the WLFZ along the Manwan Reservoir. However, further research is needed to determine the mechanisms of degradation in this zone.