Bangladesh faces huge challenges in achieving food security due to its high population, diet changes, and limited room for expanding cropland and cropping intensity. The objective of this study is to assess the degree to which Bangladesh can be self-sufficient in terms of domestic maize, rice and wheat production by the years 2030 and 2050 by closing the existing gap (Yg) between yield potential (Yp) and actual farm yield (Ya), accounting for possible changes in cropland area. Yield potential and yield gaps were calculated for the three crops using well-validated crop models and site-specific weather, management and soil data, and upscaled to the whole country. We assessed potential grain production in the years 2030 and 2050 for six land use change scenarios (general decrease in arable land; declining ground water tables in the north; cropping of fallow areas in the south; effect of sea level rise; increased cropping intensity; and larger share of cash crops) and three levels of Yg closure (1: no yield increase; 2: Yg closure at a level equivalent to 50% (50% Yg closure); 3: Yg closure to a level of 85% of Yp (irrigated crops) and 80% of water-limited yield potential or Yw (rainfed crops) (full Yg closure)). In addition, changes in demand with low and high population growth rates, and substitution of rice by maize in future diets were also examined. Total aggregated demand of the three cereals (in milled rice equivalents) in 2030 and 2050, based on the UN median population variant, is projected to be 21 and 24% higher than in 2010. Current Yg represent 50% (irrigated rice), 48–63% (rainfed rice), 49% (irrigated wheat), 40% (rainfed wheat), 46% (irrigated maize), and 44% (rainfed maize) of their Yp or Yw. With 50% Yg closure and for various land use changes, self-sufficiency ratio will be > 1 for rice in 2030 and about one in 2050 but well below one for maize and wheat in both 2030 and 2050. With full Yg closure, self-sufficiency ratios will be well above one for rice and all three cereals jointly but below one for maize and wheat for all scenarios, except for the scenario with drastic decrease in boro rice area to allow for area expansion for cash crops. Full Yg closure of all cereals is needed to compensate for area decreases and demand increases, and then even some maize and large amounts of wheat imports will be required to satisfy demand in future. The results of this analysis have important implications for Bangladesh and other countries with high population growth rate, shrinking arable land due to rapid urbanization, and highly vulnerable to climate change.

中文翻译：

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孟加拉国能否生产足够的谷物来满足未来的需求？

由于人口众多、饮食结构变化以及扩大耕地和种植密度的空间有限，孟加拉国在实现粮食安全方面面临巨大挑战。本研究的目的是通过缩小产量潜力 (Yp) 与实际产量之间的现有差距 (Yg)，评估到 2030 年和 2050 年孟加拉国在国内玉米、稻米和小麦生产方面的自给自足程度。农场产量 (Ya)，考虑了耕地面积的可能变化。使用经过充分验证的作物模型和特定地点的天气、管理和土壤数据计算了三种作物的产量潜力和产量差距，并扩大到全国。我们评估了 2030 年和 2050 年六种土地利用变化情景（耕地普遍减少；北部地下水位下降；在南部休耕地区种植；海平面上升的影响；增加种植强度；和更大份额的经济作物）和三个 Yg 关闭水平（1：单产不增加；2：Yg 关闭水平相当于 50%（Yg 关闭 50%）；3：Yg 关闭水平为 Yp 的 85% （灌溉作物）和 80% 的限水产量潜力或 Yw（雨育作物）（完全 Yg 关闭））。此外，还研究了人口增长率低和高时的需求变化，以及未来饮食中用玉米替代大米的情况。根据联合国人口中位数变量，2030 年和 2050 年三种谷物（以碾米当量计）的总需求预计将比 2010 年高 21% 和 24%。目前的 Yg 代表 50%（灌溉稻米），48 –63%（雨育水稻）、49%（灌溉小麦）、40%（雨育小麦）、46%（灌溉玉米）、和 44%（雨养玉米）的 Yp 或 Yw。在 Yg 关闭 50% 和各种土地利用变化的情况下，2030 年水稻的自给率将 > 1，2050 年约为 1，但 2030 年和 2050 年玉米和小麦的自给率将远低于 1。在所有情景中，水稻和所有三种谷物的充足率都将远高于 1，但玉米和小麦的充足率将低于 1，但硼稻面积急剧减少以允许扩大经济作物面积的情景除外。需要完全关闭所有谷物以弥补面积减少和需求增加，然后甚至需要进口一些玉米和大量小麦来满足未来的需求。该分析的结果对孟加拉国和其他人口增长率高的国家具有重要意义，