Green water is a central resource for global agricultural production. Understanding its role is fundamental to design strategies to increase global food and feed production while avoiding further land conversion, and obtaining more crop per drop. Brazil is a country with high water availability, and a major exporter of agricultural goods and virtual water. We assess here water use and water productivity in Brazil for four major rainfed crops: cotton, maize, soybeans, and wheat. For this, we use the EPIC crop model to perform a spatially explicit assessment of consumptive water use and water productivity under crop management scenarios in Brazil between 1990 and 2013. We investigate four different land-water interactions: (i) water use and productivity for different management scenarios, (ii) the potential of supplemental irrigation for productivity improvement, (iii) changes in green water use throughout the study period, and finally (iv) potential reduction of land and water demand related to agricultural intensification. The results show that, for the studied crops, green water is the main resource for biomass production, and intensification can lead to great improvements in green water productivity. The results also suggest that, despite achieving higher yields, irrigation-based intensification tends to lower overall water productivity, compared to fertilizer-based intensification strategies. This is, however, regionally and crop-specific. Furthermore, due to higher yields and water productivity, producing the same amount of crop output in irrigated or rainfed intensification scenarios would result in the reduction of resource demand, in the order of 34–58 % for cropland, and 29–52 % for water.

中文翻译：

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巴西主要雨养作物的水生产力和足迹——作物管理情景的空间明确分析

绿水是全球农业生产的核心资源。了解其作用对于设计增加全球粮食和饲料产量同时避免进一步土地转化和每滴获得更多作物的战略至关重要。巴西是一个水资源丰富的国家，也是农产品和虚拟水的主要出口国。我们在这里评估了巴西四种主要雨育作物的用水量和水生产力：棉花、玉米、大豆和小麦。为此，我们使用 EPIC 作物模型对 1990 年至 2013 年巴西作物管理情景下的耗水量和水生产力进行空间明确评估。我们调查了四种不同的土地-水相互作用：(i)不同的管理场景，(ii) 补充灌溉对提高生产力的潜力，(iii) 整个研究期间绿色用水的变化，以及最后 (iv) 与农业集约化相关的土地和水需求的潜在减少。结果表明，对于所研究的作物，绿水是生物质生产的主要资源，集约化可以大大提高绿水生产力。结果还表明，尽管实现了更高的产量，但与基于肥料的集约化策略相比，基于灌溉的集约化往往会降低整体水资源生产力。然而，这是区域和作物特定的。此外，由于更高的产量和水生产力，