Cropland Loss Research Articles

Parental hormones are associated with crop loss and family sickness following catastrophic flooding in lowland Bolivia

The physiology of fatherhood is a growing field of study, and variability in hormonal mediators of reproductive effort (e.g. testosterone, cortisol) can predict variability in paternal investment. Studies often find that lower testosterone levels are associated with increased paternal investment, though most studies are conducted under relatively stable ecological conditions. In this paper, we examine parental physiological correlates of crop loss and family health problems among Tsimane forager-horticulturalists following a catastrophic flood in lowland Bolivia. Immediately after a devastating 2014 flood that impacted >75% of Tsimane communities, we conducted structured interviews examining crop losses and morbidity, and collected saliva specimens from 421 parents (n = 292 households) to analyze cortisol and testosterone. Over 98% of interviewees reported horticultural losses, with the average family losing 88% of their crops, while 80% of families reported flood-induced injuries or illnesses. Controlling for age, body mass index, and time of specimen collection, men's testosterone was negatively associated with both absolute cropland losses (Std. β = −0.16, p = 0.037), and percent of cropland lost (Std. β = −0.16, p = 0.040). Female testosterone was not associated with crop losses. Using the same control variables, both male and female cortisol was negatively associated with a composite measure of child health burden (fathers: Std. β = −0.34, p < 0.001; mothers: Std. β = −0.23, p = 0.037). These results are discussed in the cultural context of a strong sexual division of labor among Tsimane; we highlight the physiological and psychosocial costs of experiencing a natural disaster, especially for paternal caregivers in a nutritionally and pathogenically stressed subsistence population where cultigens provide the majority of calories in the diet.

Global cropping intensity gaps: Increasing food production without cropland expansion

To feed the world’s growing population, more food needs to be produced using currently available cropland. In addition to yield increase, increasing cropping intensity may provide another promising opportunity to boost global crop production. However, spatially explicit information on the cropping intensity gap (CIG) of current global croplands is lacking. Here, we developed the first spatially explicit approach to measure the global CIG, which represents the difference between the potential and actual cropping intensity. Results indicate that the global average CIG around the year 2010 was 0.48 and 0.17 for the temperature- and temperature/precipitation-limited scenarios, respectively. Surprisingly, global harvest areas can be expanded by another 7.36 million km2 and 2.71 million km2 (37.55% and 13.83% of current global cropland) under the two scenarios, respectively. This will largely compensate the future global cropland loss due to increasing urbanization and industrialization. Latin America has the largest potential to expand its harvest area by closing the CIGs, followed by Asia. Some countries in Africa have a large CIG, meaning that some additional harvests can potentially be achieved. Our analysis suggests that reducing the CIG would provide a potential strategy to increase global food production without cropland expansion, thus also helping achieve other Sustainable Development Goals such as biodiversity conservation and climate change mitigation.

A Framework of Payment for Ecosystem Services to Protect Cropland: A Case Study of the Yangtze River Delta in China

Due to large land demand and insufficient economic incentives, stakeholders have little motivation to protect cropland during rapid urbanization. The considerable loss of cropland poses a serious threat to food security and ecological sustainability. This research proposes a framework of payment for ecosystem services (PES) to reconcile the large land demand and the need for cropland protection during economic development by identifying whom to compensate, what to pay, how much to pay, the mechanisms for payment, and verification of service delivery. Using the Yangtze River Delta as an example, the features of the PES based on supply-demand analysis, compensation quality and value standards, and payment regulation are demonstrated. The results show the effectiveness of this PES framework for handling the externality of environmental protection compared to traditional regulatory approaches. The framework will also aid in the protection of cropland by coordinating the benefits of stakeholders.

A land-cover-based approach to assessing ecosystem services supply and demand dynamics in the rapidly urbanizing Yangtze River Delta region

It is essential to appraise the impacts of land use and cover change on both the supply and demand sides of ecosystem services to formulate effective land use policies towards sustainable development. However, it remains challenging to accurately quantify ecosystem services supply and demand with comparable measurement units. Burkhard et al. (2012) proposed the use of an expert-based matrix model to assess ecosystem services supply and demand per land cover class in comparable semi-quantitative units. In this study, we improved the matrix model by measuring the levels of uncertainty that arise from expert estimation to obtain more accurate estimates, and by proposing a more adequate synthesis method to create the comprehensive index for quantifying ecosystem services supply–demand budgets with semi-quantitative estimates in the matrices. Taking the rapidly urbanizing Yangtze River Delta (YRD) region of China as an example, we used the improved matrix model to characterize relative changes in ecosystem services supply and demand in response to land use and cover change during 1985–2015. According to our land-cover-based matrix model, the two dominant land cover types (built-up area and rice fields) in the four largest cities (Shanghai, Nanjing, Hangzhou, and Suzhou) of the YRD region all exhibited greater demand for freshwater, flood protection, water purification, and erosion regulation than the provision of these hydrological services. Consequently, the four cities also exhibited greater demand for these four hydrological services than the supply of these services from local ecosystems. During the past three decades, the built-up area of the four largest cities expanded by 2.2–4.9% annually, along with an annual decrease rate of 1.9–4.6% for croplands (including rice fields and rainfed croplands). The rapid urban expansion and the huge loss of croplands caused the supply–demand budget index value of food production service to decrease by 1.7–3.7% annually, indicating large decreases in the provision of food production service, alongside large increases in food demand. Among the three categories of ecosystem services, the regulating services were in severe short supply for the four largest cities of the YRD region, while the cultural services were in sufficient supply during the past three decades. In contrast, the provisioning services shifted from sufficient supply in 1985 to insufficient status in 2015, primarily due to the rapid urban expansion. Our results illustrate clear and direct impacts of urban encroachment on both the supply and demand sides of multiple ecosystem services. This improved matrix model can be applied to assess ecosystem services supply and demand dynamics for other rapidly urbanizing regions.

GlobeLand30 shows little cropland area loss but greater fragmentation in China

Understanding of cropland dynamics in a large geographical extent is mostly based on observations of area change, while the changes in landscape pattern are hardly assessed. The total amount of cropland in China has remained relatively stable in recent years, which might suggest there was little change. In this analysis, we combine the number of cropland patches (NP) with the total cropland area (TA) for a more comprehensive characterization of cropland change in China. We use GlobeLand30–a global land cover dataset with a 30m resolution for the years 2000 and 2010–and characterize changes in TA and NP for each county as increase, stable, or decrease. This characterization shows that 703 out of 2420 counties experienced both cropland loss and increased fragmentation. The predominant cropland loss in these areas, especially in the North China Plain, is converted to artificial land. Another 212 are characterized by the opposite developments: an increase in cropland and decreased fragmentation. These counties, are mainly characterized by a conversion of forest areas and grassland areas. It suggests that the cropland conservation policy in China effectively protected the total cropland area in overall, but the consequences in terms of fragmentation might be underestimated. Counties with no obvious change in both indicators, measuring 279 counties, are mainly located in the Southeast. Our results are further compared with local level case studies: the fair consistency indicates alternatives of applying GlobeLand30 for analyzing landscape changes across scales and for cross-site comparisons.

Monitoring cropland transition and its impact on ecosystem services value in developed regions of China: A case study of Jiangsu Province

Cropland use is experiencing an intense transition in both depth and breadth with rapid development of the Chinese economy. Unwarranted land use transitions can affect the ecosystem services value (ESV) and ecosystem functions significantly. This paper reports the dynamic patterns of cropland transition (CLT) and its impact on ESV in Jiangsu Province based on land-use data from 1990, 2000, 2010, and 2013, crop yield data, empirical data related to ESV, some revisions adapted to the situation of Jiangsu, and Geo-information Tupu methods. Jiangsu has experienced rapid economic growth and urbanization, which can be seen as a microcosm of China's development. Results showed that the total area of cropland decreased markedly from 1990 to 2013. This loss of cropland took place mainly through the expansion of construction land and water area, accounting for 83.78% and 13.71%, respectively. The gain in cropland came mainly from construction land, water area, grassland, and woodland, accounting for 58.92%, 19.92%, 11.46%, and 10.22%. The transitions from 2000 to 2010 were much more significant than during 1990–2000 and 2010–2013. CLTs were accompanied by relatively concentrated distributions near towns and cities and the distributions in southern and central Jiangsu were more than in northern Jiangsu. Between 1990 and 2013, CLTs gave rise to a decrease of 6.78 million US$ ESV that was mostly caused by the transition from cropland to construction land and water area to cropland. Based on this information, some of the major implications for improving the land use policy and ecological protection policy in China were discussed. These include increased emphasis on land quality and ecological environment in balance between cropland addition and conversion, introducing ESV measures to evaluate the ecological effect of land-use planning, and establish an all-around ecological compensation mechanism.

Future urban land expansion and implications for global croplands

Urban expansion often occurs on croplands. However, there is little scientific understanding of how global patterns of future urban expansion will affect the world's cultivated areas. Here, we combine spatially explicit projections of urban expansion with datasets on global croplands and crop yields. Our results show that urban expansion will result in a 1.8-2.4% loss of global croplands by 2030, with substantial regional disparities. About 80% of global cropland loss from urban expansion will take place in Asia and Africa. In both Asia and Africa, much of the cropland that will be lost is more than twice as productive as national averages. Asia will experience the highest absolute loss in cropland, whereas African countries will experience the highest percentage loss of cropland. Globally, the croplands that are likely to be lost were responsible for 3-4% of worldwide crop production in 2000. Urban expansion is expected to take place on cropland that is 1.77 times more productive than the global average. The loss of cropland is likely to be accompanied by other sustainability risks and threatens livelihoods, with diverging characteristics for different megaurban regions. Governance of urban area expansion thus emerges as a key area for securing livelihoods in the agrarian economies of the Global South.

Land Use/Cover Change from 2001 to 2010 and its Socioeconomic Determinants in Guangdong Province, A Rapid Urbanization Area of China

Rapid economic and population growth exert profound effects on land use/cover change, especially in rapid economically developing areas, such as Guangdong Province-a pioneer of economic growth and urbanization in China. To elucidate the changes and mutual conversions of land-use types and their determinants in Guangdong Province, land-use maps of Guangdong Province from 2001 to 2010 were obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) L1B images with 500 m resolution by using the supervised classification combined support vector machine (SVM) algorithm with a decision tree. The results indicate that during the studied time period, the area of urban land and orchards increased by 4186 km2 and 3615.5 km2, respectively, while the percentage of cropland decreased from 11.46% to 10.14%. Massive urbanization and cropland loss have occurred in the region. The conversion from wasteland to urban land, and the mutual transformation between wasteland and cropland were the most prevalent in Guangdong Province. This was especially obvious from 2007 to 2010, with an annual changing rate of 5.13% and -19.33%, respectively. Several socio-economic factors were also obtained to investigate their impacts on land-use changes in Guangdong Province. It is shown that marked increases in gross domestic product (GDP), total investment in fixed assets, total retail sales of consumer goods, and the increasing development of modern service industries have led to large-scale migration, and industrial structure adjustment and improvement; consequently dramatically rapid expansion of cities and cropland loss have occurred.

How Did Urban Land Expand in China between 1992 and 2015? A Multi-Scale Landscape Analysis.

Effective and timely quantification of the spatiotemporal pattern of urban expansion in China is important for the assessment of its environmental effects. However, the dynamics of the most recent urban expansions in China since 2012 have not yet been adequately explained due to a lack of current information. In this paper, our objective was to quantify spatiotemporal patterns of urban expansion in China between 1992 and 2015. First, we extracted information on urban expansion in China between 1992 and 2015 by integrating nighttime light data, vegetation index data, and land surface temperature data. Then we analyzed the spatiotemporal patterns of urban expansion at the national and regional scales, as well as at that of urban agglomerations. We found that China experienced a rapid and large-scale process of urban expansion between 1992 and 2015, with urban land increasing from 1.22 × 104 km2 to 7.29 × 104 km2, increasing in size nearly fivefold and with an average annual growth rate of 8.10%, almost 2.5 times as rapid as the global average. We also found that urban land in China expanded mainly by occupying 3.31 × 104 km2 of cropland, which comprised 54.67% of the total area of expanded urban land. Among the three modes of growth—infilling, edge expansion, and leapfrog—edge expansion was the main cause of cropland loss. Cropland loss resulting from edge expansion of urban land totalled 2.51 × 104 km2, accounting for over 75% of total cropland loss. We suggest that effective future management with respect to edge expansion of urban land is needed to protect cropland in China.

Land use/cover change from 2001 to 2010 and its socioeconomic determinants in Guangdong Province, a rapid urbanization area of China

Rapid economic and population growth exert profound effects on land use/cover change, especially in rapid economically developing areas, such as Guangdong Province-a pioneer of economic growth and urbanization in China. To elucidate the changes and mutual conversions of land-use types and their determinants in Guangdong Province, land-use maps of Guangdong Province from 2001 to 2010 were obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) L1B images with 500 m resolution by using the supervised classification combined support vector machine (SVM) algorithm with a decision tree. The results indicate that during the studied time period, the area of urban land and orchards increased by 4186 km2 and 3615.5 km2, respectively, while the percentage of cropland decreased from 11.46% to 10.14%. Massive urbanization and cropland loss have occurred in the region. The conversion from wasteland to urban land, and the mutual transformation between wasteland and cropland were the most prevalent in Guangdong Province. This was especially obvious from 2007 to 2010, with an annual changing rate of 5.13% and -19.33%, respectively. Several socio-economic factors were also obtained to investigate their impacts on land-use changes in Guangdong Province. It is shown that marked increases in gross domestic product (GDP), total investment in fixed assets, total retail sales of consumer goods, and the increasing development of modern service industries have led to large-scale migration, and industrial structure adjustment and improvement; consequently dramatically rapid expansion of cities and cropland loss have occurred.

Wildlife-friendly farming increases crop yield: evidence for ecological intensification.

Ecological intensification has been promoted as a means to achieve environmentally sustainable increases in crop yields by enhancing ecosystem functions that regulate and support production. There is, however, little direct evidence of yield benefits from ecological intensification on commercial farms growing globally important foodstuffs (grains, oilseeds and pulses). We replicated two treatments removing 3 or 8% of land at the field edge from production to create wildlife habitat in 50–60 ha patches over a 900 ha commercial arable farm in central England, and compared these to a business as usual control (no land removed). In the control fields, crop yields were reduced by as much as 38% at the field edge. Habitat creation in these lower yielding areas led to increased yield in the cropped areas of the fields, and this positive effect became more pronounced over 6 years. As a consequence, yields at the field scale were maintained—and, indeed, enhanced for some crops—despite the loss of cropland for habitat creation. These results suggested that over a 5-year crop rotation, there would be no adverse impact on overall yield in terms of monetary value or nutritional energy. This study provides a clear demonstration that wildlife-friendly management which supports ecosystem services is compatible with, and can even increase, crop yields.

Spectral Reflectance Characteristics of Laboratory-Grown Salt Crusts on Silty Clay and Sandy Soils

Salinization of soils has led to the loss of cropland and represents a major threat to food production. Hyperspectral imaging may prove to be useful for characterizing the spectral behavior of salt-affected soils but the methodology needs to be better evaluated. In this study, we characterized the spectral behaviors of four types of chloride salt crusts [calcium chloride dehydrate, magnesium chloride dehydrate, potassium chloride, and sodium chloride (CaCl2·2H2O, KCl, and NaCl)] formed in the laboratory. We found that (1) as salt concentration increased, the reflectance intensity decreased for both soil types, and the decreases were especially pronounced for the soils leached with the CaCl2·2H2O and MgCl2·2H2O solutions; (2) soil texture had little if any effect on reflectance; and (3) reflectance intensity decreased in the order CaCl2·2H2O < MgCl2·2H2O < KCl < NaCl. By clarifying the spectral behavior of chloride salt crusts on soils, our work demonstrates hyperspectral imaging may differentiate some types of salts and determine relative salt concentrations.

China and Environmental Sustainability: Challenges and Opportunities Ahead

Since the introduction of the market-oriented reform in 1978, China has achieved such miraculous economic growth to become the world’s second largest single-country economy. However, growing gross domestic product (GDP) as a top priority together with a rapidly growing population has resulted in a severe environmental degradation. China is today the world’s largest source of carbon emissions, world’s top consumer of primary energy and minerals, and leads the world in resource consumption and waste emissions. Domestically, energy and water shortages, water and air pollution, cropland losses, desertification, and biodiversity losses, have become really severe obstacles to a future sustainable development of the country, threatening both China’s natural ecosystems and public health. In such a context, the environmentally sustainable development challenge is arguably China’s most complex and difficult challenge that any country has ever tried to confront. The Chinese government has acknowledged the time has come to implement an alternative growth model. However, what is more striking is the coexistence of often contradictory initiatives. On the one hand, the government continues investing in renewable energy so massively that it has become the world’s largest investor in such sector. On the other, it has repeatedly declared it will not be able to reduce its dependence on coal in the short-term, it will make domestic consumption of the rising middle-class the new growth model, especially promoting car ownership, while imposing at the same time strict measures to tackle pollution. The massive urbanization process, the growing unbridled demand of natural resources and consumption, the increasing production of polluting waste will negatively impact more and more Chinese people in the near future if the country’s leadership will not be able to reconcile its socioeconomic model with environmental protection, namely to achieve environmental sustainability in the long-term. Based on an extensive relevant literature review as well as an accurate analysis of statistical data related to the topic at issue, the present research seeks therefore to broadly examine the key intertwined challenges and opportunities for China to achieve an environmentally sustainable development. By adopting a holistic approach and presenting data, the study was explorative and interpretative in nature. Given the cross-cutting nature of the topic, which requires to be analyzed from many perspectives in order to be fully understood, conducting such kind of research was not easy task. Despite this, it has attempted to give the most accurate picture and analysis to contribute to the discussion about environmental sustainability in present-day China. China’s huge environmental challenges are significant for us all. The choices the Chinese government and Chinese people are making influence not only the health and wellbeing of China but, given the global nature of environmental problems, the very future of the planet.

Topographical Characteristics of Agricultural Potential Productivity during Cropland Transformation in China

Terrain, an important limiting factor in land use change, strongly influences agricultural productivity. This study investigated the topographical characteristics of agricultural potential productivity of cropland transformations in China during the first decade of the 21st century, and explored the impacts of cropland transformations with different terrains on agricultural potential productivity as it relates to China’s national food supply. The results showed the production potential of cropland loss was much greater than that of cropland gain in most regions, and topographical characteristics of croplands losses and gains actually impacted the agricultural potential productivity in China. The losses in agricultural potential productivity was serious in regions with good terrain conditions, where the slope is lower than 5°, and the elevation is below 100 m, especially in the middle and lower Yangtze region and the Huang-Huai-Hai region. The situation for cropland loss with better quality, and expanded the worse was severe in China, and this is expected to negatively influence sustainable agricultural development in the future. This study suggests that researchers focus not only on the total area of expanded cropland but also on cropland quality, such as the different terrain conditions of the croplands, to avoid a loss in national agricultural productivity caused by the process of cropland transformation.

New Cropland on Former Rangeland and Lost Cropland from Urban Development: The “Replacement Land” Debate

In this study, a land use/land cover change analysis method was developed to examine patterns of land use/land cover conversions of cropland to urban uses and conversions of rangeland to cropland uses in the United States (US) Midwest region. We used the US 2001 and 2006 National Land Cover Datasets (NLCD) for our spatial analyses of these conversion trends. Our analysis showed that the eastern part of the Midwest, like prior periods, continued to experience losses of cropland to urban expansion but at a much more rapid rate, as this was during an expansion phase of the US real estate construction cycle. The period showed a very small net loss of cropland as the loss was being balanced by gains in cropland at the expense of rangeland lost in the western part of the Midwest. We refer to this rangeland to cropland conversion as “replacement land”. We do not suggest by replacement that there is a signal in the system that interconnects the loss of a hectare of cropland to urban land by converting a hectare of rangeland to cropland, rather we highlight this spatial trend as it raises concerns about the environmental sustainability of agriculture in the western part of the region, as production is dependent on the use of irrigation and the already stressed High Plains aquifer.

The response of grain production to changes in quantity and quality of cropland in Yangtze River Delta, China.

Cropland in Yangtze River Delta has declined drastically since economic reforms in 1978 that led to rapid economic development. Such cropland loss due to population growth has led to a decline in grain production. This study aimed at analyzing the impact of land use changes on grain production. To achieve this, the spatiotemporal dynamics of cropland during 1980-2010 were analyzed. Irrigation and soil fertility data were used as additional lines of evidence. Cropland loss had negative impacts on grain production. About 80 and 66% of grain production decreased during 1980-2005 and 2005-2010 respectively. This decline was attributed to the conversion of cropland to built-up areas. Abandoned cropland areas were mainly concentrated in regions with high irrigation capability and high soil fertility, while cropland reclamation was mainly in areas with low irrigation and soil fertility, implying that, although cropland was reclaimed, production remained low. The decline in cropland area has reinforced the chronic food insecurity in Yangtze River Delta. This study demonstrated the response of grain production to the changes in cropland quantity and quality. It also provides scientific evidence for decision makers to protect cropland and enhance grain production.

Change of cropland in typical area of Middle-Lower Yangtze Plain over the past 30 years

In order to analyze the spatial- temporal change characteristics of the cropland in typical areas of Middle-Lower Yangtze Plains from 1984 to 2010,the authors extracted the land cover information of the study area in1984,1990,1995,2000,2005 and 2010 from Landsat TM /ETM+images. The results show that the amount of cropland decreased over the past 30 years. There were three stages of the cropland change: Fast reduction,slow reduction,and sharp reduction. The total area of cropland loss was 374. 10 km2from 1984 to 1990. The decrease of cropland was 66. 09 km2from 1990 to 2000,and the loss speed was relatively slow. The cropland in the study area was reduced rapidly to 1 724. 33 km2from 2000 to 2010. Most of the lost cropland was transformed into the construction land,and the cropland in cities along the Yangtze River,such as Nanjing,Maanshan,and Wuhu,was decreased more seriously than that in counties. The speed of urbanization was accelerated. Moreover,plenty of cropland was turned into ponds to breed fish and crabs around the Shijiu Lake and the Gucheng Lake,particularly in western regions where the conversion was prominently frequent from 1990. On the other hand,cropland was increased along the boundary of cropland and mountain from 1984 to 2000. After that,the cropland decreased because of the implementation of returning cropland to forest and creating economic forest.

Spatial Pattern of Land Use Change and Its Driving Force in Jiangsu Province

Scientific interpretation of the mechanism of land use change is important for government planning and management activities. This study analyzes the land use change in Jiangsu Province using three land use maps of 2000, 2005 and 2008. The study results show that there was a significant change in land use. The change was mainly characterized by a continuous built-up land expansion primarily at the expense of cropland loss, and the trend became increasingly rapid. There was an obvious regional difference, as most of the cropland loss or built-up land expansion took place in southern Jiangsu, where the rate of built-up land expansion was faster than in central and northern Jiangsu. Meanwhile, the spatial pattern changed remarkably; in general, the number of patches (NumP) showed a declining trend, and the mean patch size (MPS) and patch size standard deviation (PSSD) displayed increase trends. Furthermore, the relative importance of selected driven factors was identified by principal component analysis (PCA) and general linear model (GLM). The results showed that not only the relative importance of a specific driving factor may vary, but the driven factors may as well. The most important driven factor changed from urban population (UP), secondary gross domestic product (SGDP) and gross domestic product (GDP) during 2000–2005 to resident population (RP), population density (POD) and UP during 2005–2008, and the deviance explained (DE) decreased from 91.60% to 81.04%. Policies also had significant impacts on land use change, which can be divided into direct and indirect impacts. Development policies usually had indirect impacts, particularly economic development policies, which promote the economic development to cause land use change, while land management policies had direct impacts. We suggest that the government should think comprehensively and cautiously when proposing a new development strategy or plan.

Mudflat soil amendment by sewage sludge: Soil physicochemical properties, perennial ryegrass growth, and metal uptake

The fast pace of cropland loss in China is causing alarm over food security and China’s ability to remain self-reliant in crop production. Mudflats after organic amendment can be an important alternative cropland in China. Land application of sewage sludge has become a popular organic amendment to croplands in many countries. Nevertheless, the land application of sludge to mudflats has received little attention. Therefore, the objective of the present work was to investigate the impact of sewage sludge amendment (SSA) at 0, 30, 75, 150 and 300 t ha−1 rates on soil physicochemical properties, perennial ryegrass (Lolium perenne L.) growth and heavy metal accumulation in mudflat soil. The results showed that the application of sewage sludge increased organic matter (OM) content by 3.5-fold while reducing salinity by 76.3% at the 300 t ha−1 rate as compared to unamended soil. The SSA reduced pH, electric conductivity (EC) and bulk density in mudflat soil, increased porosity, cation exchange capacity (CEC) and contents of nitrogen (N), phosphorus (P), exchangeable potassium ions (K+), sodium ions (Na+), calcium ions (Ca2+) and magnesium ions (Mg2+) in comparison to unamended soil. There were 98.0, 146.6, 291.4 and 429.2% increases in fresh weight and 92.5, 132.4, 258.6 and 418.9% increases in dry weight of perennial ryegrass at 30, 75, 150, and 300 t ha−1, respectively, relative to unamended soil. The SSA increased metal concentrations of aboveground and root parts of perennial ryegrass (p < 0.05). The metal concentrations in perennial ryegrass were Zn > Cr > Mn > Cu > Cd > Ni, and the metal concentrations in roots were significantly higher than aboveground parts. The metal accumulation in perennial ryegrass correlated positively with sludge application rates and available metal concentrations in mudflat soil. Land application of sewage sludge was proved to be an effective soil amendment that improved soil fertility and promoted perennial ryegrass growth in mudflat soil. However, heavy metal accumulation in plants may cause food safety concern.

Intensifying the Countryside: A Sociological Study of Cropland Lost to the Built Environment in the United States, 2001–2006

This study illuminates the systemic drivers of land-use intensification with the example of cropland lost in the construction of the built environment. The analysis integrates county-level variables from US government sources with data from the National Land Cover Database, which tracks permutations of specific land-use transitions over time. In a fixed-effects analysis, the area of cropland lost to the built environment is regressed on different measures of population and economic growth. Results indicate that natural increase and net migration differentially affect the loss of cropland at the local level across the continental United States, challenging the traditional focus in environmental sociology on overall population growth. This study also advances the concept of aristocratic conservation as a process by which increasing residential affluence slows down the intensification of land. The results of the analysis are discussed in terms of what land-use intensification means for environmental sustainability and town-country relations.