Agriculture intensifies soil moisture decline in Northern China

Abstract

Northern China is one of the most densely populated regions in the world. Agricultural activities have intensified since the 1980s to provide food security to the country. However, this intensification has likely contributed to an increasing scarcity in water resources, which may in turn be endangering food security. Based on in-situ measurements of soil moisture collected in agricultural plots during 1983–2012, we find that topsoil (0–50 cm) volumetric water content during the growing season has declined significantly (p < 0.01), with a trend of −0.011 to −0.015 m3 m−3 per decade. Observed discharge declines for the three large river basins are consistent with the effects of agricultural intensification, although other factors (e.g. dam constructions) likely have contributed to these trends. Practices like fertilizer application have favoured biomass growth and increased transpiration rates, thus reducing available soil water. In addition, the rapid proliferation of water-expensive crops (e.g., maize) and the expansion of the area dedicated to food production have also contributed to soil drying. Adoption of alternative agricultural practices that can meet the immediate food demand without compromising future water resources seem critical for the sustainability of the food production system.

Comparison of temporal trends from multiple soil moisture data sets and precipitation: The implication of irrigation on regional soil moisture trend

“…It is noted that the majority of massive agricultural infrastructure construction projects were conducted since the 1990s, as can be seen from the rapid increase in AEI time series after 1995 (Fig. 6b) and the rapid expansion of total crop area ever since (Liu et al, 2015). Prior to this period, soil moisture was more explicitly controlled by climate variability, which partly explains the difference in trend analysis results of this study and those using land surface model at longer time frame.…”

“…cn/english/). The significant depletion was also evidenced by various investigations on groundwater resources of this region using the Gravity Recovery and Climate Experiment (GRACE) satellites (Liu et al, 2015;Tang et al, 2013), using groundwater monitoring wells (Wang et al, 2009), and using tracer experiment (Tan et al, 2014). The excessive groundwater extraction is considered as the "external" water sources to local surface soil water, and contributes to the large difference in observed trends between soil moisture and precipitation.…”

A non-linear Granger-causality framework to investigate climate–vegetation dynamics

“…On the other hand, the variance of NDVI explained in other areas, such as the Eurasian taiga, tropical rainforests, or China, is again below 10 %. We hypothesize two potential reasons: (a) the uncertainty in the observations used as target and predictors are typically larger in these regions (especially in tropical forests and at higher latitudes), and (b) these are regions in which vegetation anomalies are not necessarily primarily controlled by climate but may be predominantly driven by phenological and biotic factors (Hutyra et al, 2007), occurrence of wildfires (Van der Werf et al, 2010), limitations imposed by the availability of soil nutrients (Fisher et al, 2012), or agricultural practices (Liu et al, 2015). Nonetheless, the explained variance shown in Fig.…”

China’s Land Resources Dilemma: Problems, Outcomes, and Options for Sustainable Land Restoration

“…Such activities increase farmers' welfare in the short term [35] but, with poor land management and insufficient institutional support, they lead to undesired long-term ecological consequences. For example, intensified farming lowers soil quality, depletes soil water, and accelerates farmland degradation [36], while improper practices (e.g., cultivation on untreated industrial land and irrigation using unsafe wastewater) contaminate soil and surface and underground water [37]. With an increased area of polluted land for agriculture, China's food security is threatened by a shrunken suitable sown area.…”