Abstract
AbstractEarth's water resources are critical for supporting livelihoods and food security but are being increasingly overexploited to support global agriculture. Diversifying cropping systems could potentially resolve unsustainable water use but trade‐offs with other aspects of sustainability and food security have not yet been assessed. We performed a detailed analysis of 31 different field crop rotations conducted during 1990–2019 in the North China Plain, to assess the potential impact of crop diversification on actual evapotranspiration (ETa), changes in regional groundwater table, grain yield, economic output, and water use efficiency (WUE) and to identify configurations that can achieve co‐benefits across multiple dimensions. We found that a combination of lowering the cropping index (i.e., harvest frequency), incorporating fallow periods, and introducing higher‐value crops into the currently dominant winter wheat–summer maize double cropping system can reduce growing season ETa by as much as 31%, mitigate groundwater decline by 19% or more, and increased economic output and economic WUE by more than 11% and 3%, respectively. We also found that multiple diversified wheat‐maize–based rotations—all with rotation lengths greater than 2 years—achieve co‐benefits across all evaluated dimensions. This study provides new empirical evidence of the opportunities for diversified crop rotations to balance the multiple objectives of food production, sustainable groundwater use, and farmer profitability. Extending this solution to other water‐stressed agricultural regions could be an effective strategy in achieving more sustainable food production system globally.
Highlights
As the breadbasket of China, the North China Plain (NCP) accounts for 23% of China's total grain production during the past four decades (National Bureau of Statistics of China, 2019a) (Figure 1a, Figure S1)—including 51% of the nation's wheat, 35% of its maize, and a large fraction of other key crops such as peanuts and soybeans (National Bureau of Statistics of China, 2019a) (Figure 1b, Figure S2), and agriculture is responsible for 62–7 0% of the region's water usage (China Water Resources Bulletin, 2019)
Our analysis indicates that diversifying crop rotations offers major opportunities to reduce trends of unsustainable water use in North China Plain, while keeping grain output and economic profitability at sustainable levels and greatly increasing the economic water use efficiency
This study identified that reducing the cropping index— ranging from 2 for the intensive wheat-maize system to 1 for single cropping systems—introducing fallow periods, and alternating complementary crop types between intensive wheat-maize rotations can help to balance groundwater drawdown, food production, and the economic output of agriculture in the NCP
Summary
Groundwater delivers water for nearly 2 billion people worldwide, supplies more than 40% of irrigation water, and enables 13% of total food production (de Graaf et al, 2019), by overcoming local rainfall limits. With the completion of numerous empirical studies on the relationship between diversified crop rotations and water use, there is a need to synthesize the findings to inform policy on options for improving sustainability To address this knowledge gap, here, we use years from 1990 to 2019 of empirical results to perform a detailed synthesis analysis to assess multiple outcomes of diversified crop rotations tested in the NCP (Figure 2) and to compare their (a) water consumption (ETa), groundwater depletion or gain, and WUE (water use efficiency, kg of product per m3 of evapotranspiration water), (b) productivity (i.e., yield), and (c) economic output, all relative to the conventional winter wheat–summer maize system. The study provides essential information for utilizing crop rotations as an effective means to enhance the sustainability of food production across multiple outcomes and to minimize trade-offs
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