IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires C1417DSE, Argentina
IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires C1417DSE, Argentina.
Proc Natl Acad Sci U S A. 2018 Mar 6;115(10):2335-2340. doi: 10.1073/pnas.1717072115. Epub 2018 Feb 20.
We analyzed crop production, physical inputs, and land use at the country level to assess technological changes behind the threefold increase in global crop production from 1961 to 2014. We translated machinery, fuel, and fertilizer to embedded energy units that, when summed up, provided a measure of agricultural intensification (human subsidy per hectare) for crops in the 58 countries responsible for 95% of global production. Worldwide, there was a 137% increase in input use per hectare, reaching 13 EJ, or 2.6% of the world's primary energy supply, versus only a 10% increase in land use. Intensification was marked in Asia and Latin America, where input-use levels reached those that North America and Europe had in the earlier years of the period; the increase was more accentuated, irrespective of continent, for the 12 countries with mostly irrigated production. Half of the countries (28/58), mainly developed ones, had an average subsidy >5 GJ/ha/y (with fertilizers accounting for 27% in 1961 and 45% in 2014), with most of them (23/28) using about the same area or less than in 1961 (net land sparing of 31 Mha). Most of the remaining countries (24/30 with inputs <5 GJ/ha/y), mainly developing ones, increased their cropped area (net land extensification of 135 Mha). Overall, energy-use efficiency (crop output/inputs) followed a U-shaped trajectory starting at about 3 and finishing close to 4. The prospects of a more sustainable intensification are discussed, and the inadequacy of the land-sparing model expectation of protecting wilderness via intensified agriculture is highlighted.
我们分析了各国的作物生产、物质投入和土地利用情况，以评估 1961 年至 2014 年期间全球作物产量增长三倍背后的技术变化。我们将机械、燃料和肥料转化为嵌入能源单位，这些能源单位加起来，为负责全球 95%产量的 58 个国家的作物提供了农业集约化（每公顷的人为补贴）的衡量标准。全世界每公顷投入的使用量增加了 137%，达到 13 艾焦耳，占世界初级能源供应的 2.6%，而土地利用仅增加了 10%。亚洲和拉丁美洲的集约化程度显著提高，这些地区的投入使用水平达到了该时期早些年北美和欧洲的水平；无论在哪个大陆，灌溉生产为主的 12 个国家的投入增加更为明显。一半的国家（58 个国家中的 28 个），主要是发达国家，平均补贴>5 吉焦耳/公顷/年（其中肥料在 1961 年占 27%，2014 年占 45%），其中大多数（23/28）使用的面积与 1961 年相同或更小（净节约土地 3100 万公顷）。其余大多数国家（24/30 个投入<5 吉焦耳/公顷/年），主要是发展中国家，增加了其作物种植面积（净扩大土地面积 1350 万公顷）。总的来说，能源利用效率（作物产量/投入）遵循 U 形轨迹，起点约为 3，终点接近 4。讨论了更可持续的集约化前景，并强调了通过集约化农业保护荒野的土地节约模式预期的不足。
