The nitrogen economy of rice-livestock systems in Uruguay
The nitrogen economy of rice-livestock systems in Uruguay
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DOI：
10.1016/j.gfs.2021.100566
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发表时间：
2021-08-11
影响因子：
8.9
通讯作者：
Haefele, Stephan M.
中科院分区：
文献类型：
--
作者：
Castillo, Jesus;Kirk, Guy J. D.;Haefele, Stephan M.
几十年来，全球趋势是从混合耕作和综合作物-牲畜系统转向更密集的单一商品系统。这扭曲了当地和全球的养分平衡，造成环境污染和土壤养分耗竭。未来的粮食系统应包括营养预算紧张的综合作物畜牧系统。对于氮，需要详细了解过程、通量（包括气态形式）和组分水平的预算，以设计在整个营养链中具有高氮利用效率的生产系统。在乌拉圭，50多年来一直实行一种独特的水稻-牲畜系统，水稻产量很高（平均谷物产量> 8兆公顷），牲畜产量达到平均水平（每公顷增加120公斤活重）。本研究的目的是量化该系统的氮平衡和NUE的组成部分，以了解其长期的可持续性，并得出结论，为其他地区。对过去16年来每个组成部分的国家一级统计数据的分析表明，水稻、牲畜和整个系统的氮平衡分别为+3.49、+2.20和+2.22千克氮公顷（-1）年（-1）。基于平均值的N保留在食用食品，NUE值为65.7%，13.2%和23.1%，分别为水稻，牲畜和整个系统。虽然牲畜的NUE在此期间没有变化，但由于化肥使用量增加，水稻部分的NUE下降。通过更好地集成系统组件，可以进一步提高N效率。提高系统一级NUE的行动包括提高牧场和牲畜生产力，控制水稻氮肥的使用。紧密结合的作物-牲畜系统可以在重塑全球农业以实现粮食安全、环境和社会经济可持续性目标方面发挥重要作用。
Over many decades there has been a global trend away from mixed farming and integrated crop-livestock systems to more-intensive single commodity systems. This has distorted local and global nutrient balances, resulting in environmental pollution as well as soil nutrient depletion. Future food systems should include integrated crop livestock systems with tight nutrient budgets. For nitrogen (N), detailed understanding of processes, fluxes - including of gaseous forms - and budgets at a component level is needed to design productive systems with high N use efficiency (NUE) across the full nutrient chain. In Uruguay, a unique rice-livestock system has been practiced for over 50 years, attaining a high production level for rice (mean grain yields > 8 Mg ha(-1)) and an average level for livestock (120 kg liveweight gain ha(-1) y(-1)). The aim of this study was to quantify the components of the N balance and NUE of this system, so as to understand its long-term sustainability, and draw conclusions for other regions. Analysis of country-level statistics for each component over the last 16 years shows tight N balances of +3.49, +2.20 and +2.22 kg N ha(-1) yr(-1) for rice, livestock and the whole system, respectively. Based on average values of N retained in edible food products, NUE values were 65.7, 13.2 and 23.1% for rice, livestock and the whole system, respectively. While NUE of livestock was unchanged over the period, NUE of the rice component decreased due to increasing fertiliser use. Further gains in N efficiency are possible by better integrating the system components. Actions to increase system level NUE include raising pasture and livestock productivity and controlling the increasing use of N fertilisers in rice. Tightly integrated crop-livestock systems can play a significant role in re-shaping global agriculture towards meeting food security, environmental and socioeconomic sustainability targets.