The Land-Water-Food-Environment nexus in the context of China's soybean import

https://doi.org/10.1016/j.advwatres.2021.103892Get rights and content

Highlights

  • We conducted a comprehensive analysis of China's land-water-food-environment nexus.

  • China's rapid soybean import led to area decrease in soybean and increase in other crops.

  • Cropland conversion resulted in increases in crop production, water use and N application.

Abstract

Soybean import accounts for 90% of China's total domestic soybean supply. Such import has a substantial impact on how the country's resources are used as well as on its environment. In this study, we performed a national-scale assessment of the impact of soybean import on domestic cropland conversion, crop production, water use and nitrogen (N) fertilizer application. Results show that soybean production in China decreased by 26% (4.46 million tons) and sown areas were reduced by 25% (2.39 million ha) from the peak of 2004 to 2016. Of the areas taken out of the soybean production, 70% were converted to maize, 20% to rice, 3% to vegetables and 7% to fruits during this period. As a result of the cropland conversion, the production of maize, rice, vegetables and fruits increased by 10.42, 3.34, 2.49 and 3.26 million tons respectively. However, irrigation water use in the areas that were converted to the cultivation of the four types of crops increased by 96.42% (3.05 km3), with much of it coming from northern provinces where water is generally scarce. The application of N fertilizer increased by 256.65 thousand tons (almost 5 times) on the converted areas, partly due to the loss of the N-fixing soybean cultivation. Although a large quantity of virtual water and land were imported through soybean trade, the water use and N application were increased in reality. The analysis of the land-water-food-environment nexus in the context of soybean import provides comprehensive and useful information about the benefits and trade-offs associated with China's international soybean trade.

Introduction

International food trade is an important means for many countries to meet their domestic food demand, especially for water-scarce countries, such as those in the Middle East and North Africa, as well as land-limited countries, such as the Netherlands and Japan (Lee et al., 2019; Oki et al., 2003; D’Odorico et al., 2018, Yang et al., 2003, Zhao et al., 2016). It was estimated, for example, that by importing 905 thousand tons of wheat from France, Morocco saved 3.77 km3 yr−1 (cubic kilometer per year) of its water during the period of 1996-2005 (Mekonnen and Hoekstra, 2010). It is widely believed that the importing of virtual water through the trade of agricultural products is beneficial for alleviating water stress and land scarcity in importing countries or regions (Liu et al., 2018b; Liu et al. 2019; Dalin and Rodriguez-Iturbe, 2016; Zhang et al., 2011; Chapagain et al., 2006).

In addition to addressing water and food trade relationships in importing countries, a number of studies have addressed certain aspects of the environmental impact of such trade in exporting countries (or regions). For example, Hansern et al. (2008) and DeFries et al. (2010) found that deforestation in many countries in humid tropical regions positively correlates with their exports of agricultural products between 2000 and 2005. Similarly, in the case of water, several studies have documented the increased water scarcity and overexploitation of aquifers in some major crop producing regions in exporting countries, such as the Ogallala basin in the USA (Marston & Konar, 2017; Dalin et al., 2017; Hoekstra & Mekonnen, 2012; Oki & Kanae, 2004).

On the other hand, the international food trade could also have negative effects on the water stress and the environment in importing countries (Sun et al., 2017; Pechlaner and Otero, 2010). Some studies have found that although food import may save an amount of water that would otherwise be needed for producing the imported food, in reality such imports have rarely helped to alleviate water stress. This is because water saved from the food trade is often used to expand irrigation to increase both production and income (Dalin et al., 2014; Zhao et al., 2015; Han et al., 2015; Yang et al., 2018; Zhuo et al., 2016; Zhang et al., 2012). This could also lead to increased water pollution due to high nitrogen (N) input and high N losses (Liu et al., 2016; Liu et al., 2018b; Sun et al., 2018).

Interconnections between land-water-food-environment are complicated. Investigating these interconnections from the nexus perspective has attracted many researches particularly in the past decade (Liu et al., 2017; Liu et al., 2018a; Zhao et al., 2018; Taniguchi et al., 2017; Ren et al., 2018; Pastor et al., 2019). There have been many studies addressing the nexus issues on local, regional and global scales (Tian et al., 2018, 2019; Ibarrola-Rivas et al., 2017; Zhuo et al., 2019). For example, Rulli et al. (2013) conducted a global level study assessing the mismatch in the distributions of water and land resources, and the important role of food trade in the spatial reallocation of these resources. Pastor et al. (2019) evaluated the possible impact of climate change on global land use, water consumption and food trade under several water regulation policy scenarios. Chiarelli et al. (2018) investigated the land-water-food nexus of world rubber production and found that rubber plantation expansion was at the expense of agricultural land for staple crops, and has caused increased usage of fertile land and freshwater. The study by Dalin et al., (2014) found that the increasing volume of food trade in China could increase the pressure on areas with limited water and land resources by outsourcing large amounts of virtual water and land. Liu et al. (2019) analyzed the properties and connections of the food-related virtual water and land flows in China by establishing a network-based framework and found that green and grey water consumption associated with food production and trade accounted for a huge proportion of the total water consumption in water-scarce regions. These above studies have tackled the nexus issues with different focuses, locations and scales. However, they mostly address the nexus relating to food trade in exporting regions. Few studies have examined the positive/negative effects on importing regions from the nexus perspective. No study has conducted a comprehensive investigation on the nexus of water-land-food-environment in the context of large soybean import in China.

In China, the demand for soybean as animal feed, and to a lesser extent for other direct and indirect forms of consumption, has increased substantially since the 1990s. The increased demand has been met exclusively by imports from other countries, particularly Brazil, USA and Argentina. Since 2000 the quantity of soybean import has increased rapidly. China is now the largest soybean importer, accounting for 60% of global total imports (FAOSTAT, 2016). While, due to political and economic reasons, the soybean production in China has lost its competitiveness and has been shrinking since the early 2000s. On the political aspect, after joining WTO in 2001, China opted to totally open the soybean market partly (among many other reasons) because soy is considered less important than staple grains (wheat, maize and rice) to the national food security. As a result, soybean imports surged while domestic soybean cultivation shrunk without the supporting policy from the Chinese government (Liu et al., 2020; Chen et al., 2019; Zhu and Jiang, 2014). On the economic aspect, imported soybean is highly competitive for its lower cost and price than the domestic soybean (for many reasons). On the other hand, economic water productivity (CNY m−3) of soybean is not only lower than cash crop, like vegetables and fruits, and also lower than that of maize, and profit from rice producing is 2~3 times higher than that from soybean producing (NCCIAP, 2017). Additionally, the high demand for fruits and vegetables have also driven prices high. Farmers are welling to switch to produce crops of higher profit.

Importing soybean, rather than producing it domestically, freeing up cropland for more important or with higher commercially profits crops, such as maize, rice, fruits, and vegetables. However, such cropland conversion may result in additional impacts, due to different intensities and productivities of inputs, as well as different environmental consequences. Thus, it is of importance to investigate the trade-offs of soybean imports from a water, food, land, environment nexus perspective. China imports a huge amount of soybean each year (Liu et al., 2020). The import has had significant impacts on domestic land use for crop production. The situation in China provides a unique case to explore the complex nexus involved in the soybean imports.

The objective of this study is to provide a comprehensive analysis of the effects of China's soybean import on land-use change, water use, crop production, and the N application, both from a virtual and a real perspective. The analysis focuses on the situation between 2000 and 2016, during which the domestic soybean production has been declining while its imports have been substantially increasing (China Statistical Yearbook, 2017).

Section snippets

Data description

The data for domestic sown areas for the period 1980-2016, and yield and production of the five types of crops (soybean, maize, rice, vegetables, and fruits) for the period 2000-2016 were taken from China Statistical Yearbooks at the provincial level (http://data.cnki.net/yearbook/Single/N2018110025). Data about China's soybean import quantity for the period 2000-2016 was also derived from the same data source.

The irrigation quotas for the crops were obtained from the water-use quotas regulated

Spatial and temporal distribution of soybean production in China

Between 2000 and 2016, China's soybean import increased 7 times, from 10.42 million tons to 83.91 million tons (Fig. 2). By contrast, the domestic soybean production decreased gradually since 2004 (17.4 million tons). The total domestic soybean consumption increased from 25.83 million tons in 2000 to 96.85 million tons in 2016. The percentage of imported soybean in the total consumption increased from 40.3% in 2000 to 86.6% in 2016 at an annual incremental rate of 3%. The soybean export from

Impact of cropland conversion on water scarcity and food supply

In the major soybean producing provinces in China, cropland conversion led to an increase in demand for irrigation water by more than 3 km3 in 2016 compared with 2004. These increases can mainly be observed in the north of China (73.8%) (Fig. S4), where water scarcity is severe and irrigation generally comes from groundwater withdrawal. For example, Heilongjiang, Jilin, Inner-Mongolia, Hebei, and Shaanxi account for 22.5%, 6.1%, 4.5%, 15% and 10.6% respectively of the national increase in the

Conclusion

This study provides an integrated analysis of the effects of China's soybean import on its water use, land-use change, crop production and N application across different regions. Our overall findings suggest that soybean import is becoming increasingly important in China's food supply system, particularly for animal products. As for the effects on water use, although a large quantity of virtual water is imported through the influx of soybean, the demand for irrigation water in converted

Declaration of Competing Interest

The authors declare that they have no known competing financial interests of personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (31871518), National Key Research and Development Program of China (2017YFD0300908), and Natural Science Foundation of Hebei Province (D2020205009).

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