Modeling power and workforce demand in French field agriculture highlights variability, fleet redundancy, and magnitude comparable to renewable electricity generation

• Variability of power demand for agricultural field tasks in France is modelled. • Power demand is highly variable, peaking at 18 GW during tillage operations. • Power demand is 18% of installed engine power, revealing fleet redundancy. • Workforce requirement varies strongly and peaks at 30% of total workers. • Machinery power demand is comparable to wind and solar power generation. Mechanized agriculture relies heavily on fossil fuels for field operations, while facing decarbonization and environmental sustainability challenges. Phasing out fossil fuels requires alternative energy supply that can provide sufficient power to perform field tasks. However, the variability of agricultural power demand remains unexplored, yet it is crucial for anticipating energy transition to renewable flows. Here, we fill this gap by modelling on-field power demand distribution over a full cropping season based on production practices from public surveys and using national-scale French agriculture as a case study. Results show high variability in power demand, ranging from below 5 to above 12 GW during autumn tillage. Compared to total installed engine power, the load factor of tractors and combine-harvesters peaks at about 18% and 23% respectively. This indicates substantial fleet redundancy, which is in part necessary to accommodate unpredictability in field working conditions. By assessing scenarios of agroecological practices, we show that no-till practices help reduce peak power demand, whereas organic practices result in a marginal power demand increase. In parallel, we assess workforce requirement for field driving of machinery. This requirement peaks simultaneously with power demand at one-third of total workers and accounts for 12% of annual working time in agriculture. Our findings highlight trade-offs between farming system organization, practices and on-field power demand, revealing that the latter is currently comparable in scale to renewable (wind and solar) power generation in France. The results underscore the need to integrate power demand analysis of fossil-fueled activities into energy transition policies and planning.