From 1998 to the end of October, 2012, the European Journal of Soil Science and Soil Use and Management published 94 papers authored by Chinese researchers. The number of papers has increased from two per year between 1998 and 2000 to 17 per year in 2011, and citations have also risen from two in 1998 to 120 in 2011 (Figure 1). The increasing research attention by Chinese scientists to soil science can be explained for the following reasons: (i) the vast territory and large climatic variation within China have resulted in diverse soil types, which provide considerable research opportunities, (ii) agriculture has a very long history in China, and this has had a dramatic impact on the environment, particularly on soil because a better understanding of soil productivity and sustainability is urgently required and (iii) with the fast development of the Chinese economy, the central government has increased greatly investment in scientific research, thus providing the resources needed to support fundamental and applied research.
This virtual issue is a dual publication in both the European Journal of Soil Science and Soil Use and Management, and can be accessed without cost online (www.wileyonlinelibrary.com/journal/sum and www.wileyonlinelibrary.com/journal/ejss). The virtual issue provides a collation of research papers authored by Chinese soil scientists which have been published in the European Journal of Soil Science or Soil Use and Management and which give a flavour of the breadth and types of the research. Twenty papers are included covering the following five topics: 1) carbon and organic matter; 2) physical and chemical processes, functions and management; 3) biological interactions; 4) nutrient management and 5) soil degradation and impact of land management. These five research areas overlap to some extent and classification of some papers is difficult, but some important research themes can be recognized.
1) Carbon and organic matter
Carbon cycling has a major influence on global climate change and is much influenced by the effects of this phenomenon. There are very important processes involved with carbon cycling in terrestrial systems including the effects of human activities. Chinese soil scientists have studied carbon stability as well as the properties of humic substances as affected by tillage (Wu, 2011; He et al., 2009) and soil amendment (Dou et al., 2008). Organo-mineral complexes play a significant role in stabilizing organic carbon. Studies on carbon stability require both microscopic and macroscopic approaches. Chemical and biological techniques are combined in order to understand the mechanisms of carbon sequestration, while regional and global carbon distribution and transformation are the basis for indentifying carbon sinks and sources. Chinese soil scientists have an advantage given the diversity of soils in their country.(Ye et al., 2008; Guo et al., 2007). A great challenge to studies on carbon stability in China is that different processes have varying roles in different regions, and thus it is important to identify region-specific processes that govern carbon cycling and which will have relevance in other parts of the world.
2) Physical and chemical processes, functions and management and 3) Biological interactions
An individual paper can be categorized as one focusing on physical, chemical or biological processes, however, there is usually a large degree of inter-dependence between such processes. The input of various chemicals, or change in physical conditions such as temperature and soil water alters the environment for soil organisms, while biological processes determine the uptake of soil nutrients, preservation of soil carbon and the release of greenhouse gases. Soil is the largest sink for various contaminants and thus is of major importance in maintaining a sustainable environment in which, physical, chemical and biological processes interact. Studies on soil physical properties such as soil temperature (Gao et al., 2008), chemical and biological behaviour which influence greenhouse gas emission (Min et al., 2012; Xu & Inubushi, 2009)) and microbial activities (Zhang et al., 2007) are included as examples in this virtual issue. Chinese soil scientists have studied the speciation, distribution and removal, mostly by biological methods, of heavy metals in contaminated soils (Wang & Staunton, 2006). Recent research has centred on emerging anthropogenic chemicals, such as manufactured nanoparticles, pharmaceuticals (especially antibiotics) and personal care products. These chemicals occur only after industrial development, and thus their behaviour and risks are unknown; as a result, risk assessment studies are urgently needed. In the last few decades, along with the rapid development of large-scale livestock and poultry industries in China, there has been an increase in contaminants in manures from livestock and poultry (such as heavy metals, residues of animal medicine, salts, and harmful bacteria) which have entered the environment through manure application as soil amendments. More research attention has been given to the fate of these contaminants including sorption, leaching, bonding and bio- and chemical-degradation.
4) Nutrient management
Because of limited farmland and population pressure, the application of fertilizers to farmland in China is intensive and there is a worrying trend in the decreasing efficiency of applied fertilizers in the last three decades as demonstrated by a number of papers in this virtual issue. China consumes currently about 30% of the global N-fertilizers, but only 30–35% is utilized by crops. Most of the N-fertilizers thus enter the environment with potential harmful effects. Agricultural-related non-point pollution has been a major environmental problem in China (Wang et al., 2004), as also indicated by the widespread eutrophication of inland lakes. Sustainable management of soil fertility is a very important challenge for Chinese soil scientists. Since the 1970s, long-term fertilizer experiments have been established in China and have produced valuable data. Chemical fertilizers as well as soil amendments, such as manures from livestock (Duan et al., 2011), organic matter and biomass as well as biochars have been applied. Powerful analytical techniques such as 13C cross-polarized magic angle spinning nuclear magnetic resonance (CPMAS NMR) (Zhang et al., 2009) and stable isotope tracing (Zhang et al., 2012) methods have been used to investigate the impact of fertilizer applications on nutrient cycling and the properties of soil organic matter. Multi-disciplinary approaches involving plant nutrition, soil science and agronomy are needed to ensure the optimal use of applied soil nutrients; with such approaches greater crop yield, and improved efficiency of nutrient uptake can be achieved.
5) Soil degradation and impact of land management
With the fast economic development of China, land-use has changed dramatically in the last two decades. Farmland and residential land use have both expanded with the increase in residential land use the greater. Population increase is the main driving force to land-use change, but state macroscopic agricultural policies also play an important role in structural changes. In many regions of China, soils are under-going rapid degradation (Liang et al., 2009). An important area of research for Chinese soil scientists is to assess soil degradation, erosion and fertility in different ecological systems (Liu et al., 2002; Huang et al., 2004) or different land-uses (Meng et al., 2001; Liu et al., 2007). This approach provides useful information for optimizing soil-use and management. For example, tillage can induce erosion and deposition of soils, while terracing is an effective method of soil conservation on steep slopes (Ni & Zhang, 2007), and has been used extensively to control water erosion in hilly areas of China.
Modelling and prediction of soil properties are required for soil management and particular challenges are presented by spatial variability. Previous models mostly focus on soil horizon variablity in relation to geomorphology and/or landscape position. Recent research indicates that investigations into the spatial distribution of water and soil organic matter should also consider vertical redistribution resulting from the influence of soil organisms and plants. Otherwise, predictions concerning soil water budgets and carbon storage will be incorrect. Chinese scientists have analysed both temporal and spatial variation in relation to soil use and properties. Such models are extremely important for the development of numerical hydrological and atmospheric models as well as for multi-media transport models of contaminants. Thus, they not only provide basic information important to soil management, but also contribute to the understanding of soil development and pollution control.
China has a considerable range of soil types and environmental conditions and as a result soil scientists have access to unique and diverse research resources. Because of the vast territory, the identification of region-specific processes that govern carbon cycling in different regions of China is essential for understanding the behaviour of carbon in terrestrial system. Physical, chemical and biological processes are inter-dependent in soils. With the development of the Chinese economy, many emerging anthropogenic chemicals are discharged into the environment and physical, chemical and biological concepts should be combined to understand their environmental behaviour and risks. Intensive farming in China requires optimal nutrient management. A multi-disciplinary approach will lead to greater crop yield and better use of nutrients. Modelling of soil property change and spatial variability in both horizontal and vertical directions has the potential to provide important information for soil sampling and land use management.
It is clear that soil science in China has made major steps over recent decades in making important contributions to the understanding of soil processes and improved ways of optimizing the management of soils, not just with respect to China, but on a world-wide basis. Future global pressures on food production, the effects of climate change and demands for improved maintenance of environmental quality means that continued contributions from Chinese scientists will remain very important.