Agricultural Systems ( IF 6.1 ) Pub Date : 2021-07-09 , DOI: 10.1016/j.agsy.2021.103215 Corentin Pinsard 1 , Sophie Martin 2 , François Léger 3 , Francesco Accatino 1
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CONTEXT
Agriculture in Western Europe is predominantly input-intensive (fertilisers, water, fuel, pesticides) and relies on feed imports. As a result, it is dependent on oil, which may start to decline in production in the 2020s, thus exposing the agricultural sector to potential economic stress, including increased input prices and decreased farmer purchase capacities. Therefore, it is necessary to assess the capacity of European farming systems (FS) to maintain production levels despite a decline in oil production (i.e., robustness).
OBJECTIVE
We aimed to model and compare the time variations in the animal- and crop-sourced production of three French FS under three scenarios of decreased availability of feed and synthetic fertiliser imports.
METHODS
We developed a FS-scale dynamic model that considers nitrogen flows between livestock, plant, and soil compartments. Plant production is a function of soil mineral nitrogen levels, and livestock numbers depend on feed availability. The three FS are characterised by different crop-grassland-livestock balances: (i) field crop (Plateau Picard), (ii) intensive monogastric (Bretagne Centrale), and (iii) extensive ruminant (Bocage Bourbonnais). The three scenarios consist of different combinations of synthetic nitrogen fertilisers and feed import availability declines until 2050: a decrease in synthetic fertilisers only (Synth-), a decrease in feed imports (Feed-), and a decrease in both external inputs (Synth-Feed-).
RESULTS AND CONCLUSIONS
The first two scenarios highlight the positive role of livestock effluents and permanent grasslands on the robustness of food production. In the Synth-Feed- scenario, the extensive ruminant FS exhibits robustness (no decline in food production) for 13 years, whereas the field crop FS exhibits robustness for 4 years. In contrast, the intensive monogastric FS shows decreased food production within the first year. The difference between the two crop-livestock FS can be explained by livestock density, herd composition but also plant cover composition. In the long term, all three FS show a decrease in food production between 45 and 60%.
SIGNIFICANCE
Our modelling work shed some light on the role of ruminants and permanent grasslands in making FS more robust to decreases in synthetic fertiliser and feed import availability, increasing the time without production decline after the beginning of the perturbation. For longer-time resilience, configurational changes are still necessary, however a greater robustness gives more time to implement them, therefore facilitating adaptation and transformation. Our model paves the way to the study of resilience of FS from the point of view of their crop-grassland-livestock configuration and their dependence on external inputs.
中文翻译：
用动态氮流模型评估的三种欧洲农业系统进口下降的稳健性
语境
西欧的农业主要是投入密集型（化肥、水、燃料、杀虫剂），并依赖饲料进口。因此，它依赖石油，石油产量可能会在 2020 年代开始下降，从而使农业部门面临潜在的经济压力，包括投入品价格上涨和农民购买能力下降。因此，有必要评估欧洲农业系统 (FS) 在石油产量下降的情况下保持生产水平的能力（即稳健性）。
客观的
我们旨在模拟和比较三种法国 FS 在饲料和合成肥料进口供应量减少的三种情况下动物和作物来源生产的时间变化。
方法
我们开发了一个 FS 尺度动态模型，该模型考虑了牲畜、植物和土壤隔间之间的氮流。植物产量是土壤矿物质氮水平的函数，牲畜数量取决于饲料供应。三个 FS 的特点是不同的作物-草地-牲畜平衡：（i）大田作物（Plateau Picard），（ii）集约化单胃动物（Bretagne Centrale）和（iii）粗放反刍动物（Bocage Bourbonnais）。上述三种情况包括合成的氮肥和进料进口可用性下降的不同组合直到2050：在合成肥料的降低仅（Synth-），在进料进口的降低（馈），以及在这两个外部输入的降低（Synth-饲料-）。
结果和结论
前两个情景突出了牲畜废水和永久性草原对粮食生产稳健性的积极作用。在合成饲料场景中，粗放反刍动物 FS 表现出稳健性（粮食产量没有下降）13 年，而大田作物 FS 表现出稳健性 4 年。相比之下，密集的单胃 FS 显示第一年的粮食产量下降。两种作物 - 牲畜 FS 之间的差异可以通过牲畜密度、畜群构成以及植物覆盖构成来解释。从长远来看，所有三个 FS 都显示粮食产量下降 45% 至 60%。
意义
我们的建模工作揭示了反刍动物和永久草原在使 FS 更稳健以减少合成肥料和饲料进口可用性方面的作用，增加了扰动开始后产量不下降的时间。对于更长时间的弹性，配置变化仍然是必要的，但是更大的稳健性可以提供更多的时间来实施它们，从而促进适应和转型。我们的模型从作物 - 草地 - 牲畜配置及其对外部输入的依赖的角度来看，为研究 FS 的弹性铺平了道路。
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