Cropland redistribution to marginal lands undermines environmental sustainability

Abstract

Cropland redistribution to marginal land has been reported worldwide; however, the resulting impacts on environmental sustainability have not been investigated sufficiently. Here we investigated the environmental impacts of cropland redistribution in China. Due to urbanization-induced loss of high-quality croplands in south China (∼8.5 t ha–1), croplands expanded to marginal lands in northeast (∼4.5 t ha–1) and northwest China (∼2.9 t ha–1) during 1990–2015 to pursue food security. However, the reclamation in these low-yield and ecologically vulnerable zones considerably undermined local environmental sustainability, e.g. increasing wind erosion (+3.47%), irrigation water consumption (+34.42%), fertilizer use (+20.02%), and decreasing natural habitats (−3.11%). Forecasts show that further reclamation in marginal lands per current policies would exacerbate environmental costs by 2050. The future cropland security risk will be remarkably intensified due to the conflict between food production and environmental sustainability. Our research suggests that globally emerging reclamation of marginal lands should be restricted and crop yield boost should be encouraged for both food security and environmental benefits.

Spatio-temporal patterns of oasis dynamics in China’s drylands between 1987 and 2017

“…Over the past 30 years, the Chinese government has implemented a series of major ecological projects (Bryan et (Ouyang et al 2016, Tong et al 2018. To offset the massive loss of high-quality cropland in southern China (Kuang et al 2022) and to ensure national food security despite increasing population pressure. The oases and their surrounding deserts, which are among the important strategic land reserves in China, have been transformed into cropland on a large scale (Zhou et al 2015, Lü et al 2020, Pan et al 2021.…”

“…Due to the lack of key county-level agricultural statistics, we estimated the maximum grain production potential of the oasis through actual area shares and unit yields of major crops from provincial agricultural statistics (supplementary note 3). The results indicated that cropland expansion provides great potential for grain production (supplementary figures 5(a) and (b)) and has helped to meet the increasing demand for food (Kuang et al 2022), but the environmental cost of maintaining food production cannot be neglected. Because of the large amounts of water required by agriculture and the high percentage of croplands in oases (Bai et al 2021), the increasing agricultural water demand and the decreasing soil moisture implies that the expansion of agriculture in oases may not be sustainable (Xie et al 2014).…”

How to Balance Green and Grain in Marginal Mountainous Areas?

“…Insufficient vegetation restoration will retain too much low productivity steep slope cropland, leading farmers to fall into the vicious circle known as the “poverty trap” (Figure 6), in which steep slope farming leads to poverty and poverty intensifies steep slope farming (Barbier, 2010; Cao et al., 2009b, 2021; Note S5 in Supporting Information S1). Vegetation restoration in the mountainous areas of China will not affect national food security, because the restored steep slope cropland usually has a low grain yield (Kuang et al., 2021). However, the reduction in grain production caused by excessive vegetation restoration will inevitably threaten the survival and development of farmers in the mountainous areas, which are characterized by poor, less educated, and aging (Chen et al., 2015; NFGA, 2020).…”

“…Information S1). Vegetation restoration in the mountainous areas of China will not affect national food security, because the restored steep slope cropland usually has a low grain yield (Kuang et al, 2021). However, the reduction in grain production caused by excessive vegetation restoration will inevitably threaten the survival and development of farmers in the mountainous areas, which are characterized by poor, less educated, and aging (Chen et al, 2015;NFGA, 2020).…”

Cropland Displacement Drives Carbon Emission of Grain Transport in China

“…Overall, grain production in China grew from 468.01 million-ton to 648.06 million-ton between 1990 and 2015. Spatial distributions of grain production at the prefecture level show that, as a result of cropland displacement towards "marginal land" (Kuang et al, 2021), the increase in grain production occurred primarily in the north, Northeast and Northwest of China (Fig. 2 a & b).…”