• Energy Research

Brazilian sugarcane production is converting from the traditional manual slash-and-burn to mechanized green cane harvest. The resulting sugarcane trash is mostly left on the field and plowed under at the end of a growth cycle, but it could also be recovered and used to increase the energy efficiency of ethanol. In this paper, we explore in a simulation study if straw recovery negatively impacts yields, fertilizer use, nutrient cycling, GHG emissions, and erosion; if there is an optimal recovery rate; and if different recovery rates are advisable for different soil types. We also compare the traditional slash-and-burn management to the green cane management system. Our results show that when performing straw recovery, trade-offs between different factors such as up to 1.3 t/ha lower yields or an up to 30 kg/ha higher demand for fertilizer N under low recovery rates, and higher erosion rates under high recovery rates have to be accepted. Most balanced would be a recovery rate of 40–60%, but the rate should also be adapted to soil type, with less recovery e.g. on soils prone to erosion, and to economic considerations. A comparison between green cane harvest without straw recovery and the traditional slash-and-burn method shows lower erosion rates and higher soil organic carbon contents, but also a higher fertilizer consumption due to nitrogen immobilization on areas under green cane management. Due to these trade-offs, one method cannot be unequivocally commended over the other.

Simulating organic agriculture is a considerable challenge. One reason is that few models are capable of simulating crop-pest interactions and the yield losses they cause. Here, a recently developed process-based crop-pest model (Pest-EPIC) was used to simulate conventional and organic agriculture in the European Union for the years 1995–2100. Yields and pesticide application rates were calibrated against FAOSTAT and Eurostat data. Results indicate that current pesticide application rates may be sufficient to control pests and diseases even at the end of the century. The range of simulated yield differences under organic and conventional agriculture under current conditions (e.g., wheat 21–55% (mean 34%) lower yields; potatoes 20–99% (mean 56%) lower yields) closely matched recorded values. Under climate change, the gap between yields under conventional and organic management will remain constant for some crops (e.g., at 3 t/ha for potatoes), but others—susceptible to a larger number of pests and diseases—may experience a widening of the yield gap (e.g., increase of yield difference from 0.8 to 1.6 t/ha for wheat). The presented results-dataset may in future be a valuable resource for integrated assessments of agricultural land use and policy planning, but the inherent uncertainty is still very high.

Dataset containing simulated yields of 16 crops, total pesticides application rates, total N-fertilizer applied, and NO3, organic N and organic C content of the soil in conventional (conv) and organic (org) systems for the time period 2000 to 2100. Results were aggregated to decadal means at NUTS2-level. The biogeophysical crop model Pest-EPIC was used for the simulations. Daily climate data for the model runs were provided by the Impact2C project (CSC-REMO2009-MPI-ESM-LR+ simulations for RCPs 2p6, 4p5 and 8p5). {"references": ["Rasche, L. Estimating pesticide inputs and yield outputs of conventional and organic agricultural systems in Europe under climate change. Agronomy", "Rasche, L. & Taylor, R. A. J. A pest submodel for use in integrated assessment models. T Asabe 60, 147-158 (2017)."]}

Abstract The achievement of several sustainable development goals and the Paris Climate Agreement depends on rapid progress towards sustainable food and land systems in all countries. We have built a flexible, collaborative modeling framework to foster the development of national pathways by local research teams and their integration up to global scale. Local researchers independently customize national models to explore mid-century pathways of the food and land use system transformation in collaboration with stakeholders. An online platform connects the national models, iteratively balances global exports and imports, and aggregates results to the global level. Our results show that actions toward greater sustainability in countries could sum up to 1 Mha net forest gain per year, 950 Mha net gain in the land where natural processes predominate, and an increased CO2 sink of 3.7 GtCO2e yr−1 over the period 2020–2050 compared to current trends, while average food consumption per capita remains above the adequate food requirements in all countries. We show examples of how the global linkage impacts national results and how different assumptions in national pathways impact global results. This modeling setup acknowledges the broad heterogeneity of socio-ecological contexts and the fact that people who live in these different contexts should be empowered to design the future they want. But it also demonstrates to local decision-makers the interconnectedness of our food and land use system and the urgent need for more collaboration to converge local and global priorities.

AbstractThere is an urgent need for countries to transition their national food and land-use systems toward food and nutritional security, climate stability, and environmental integrity. How can countries satisfy their demands while jointly delivering the required transformative change to achieve global sustainability targets? Here, we present a collaborative approach developed with the FABLE—Food, Agriculture, Biodiversity, Land, and Energy—Consortium to reconcile both global and national elements for developing national food and land-use system pathways. This approach includes three key features: (1) global targets, (2) country-driven multi-objective pathways, and (3) multiple iterations of pathway refinement informed by both national and international impacts. This approach strengthens policy coherence and highlights where greater national and international ambition is needed to achieve global goals (e.g., the SDGs). We discuss how this could be used to support future climate and biodiversity negotiations and what further developments would be needed.

AbstractMost of Earth's biodiversity is found in 36 biodiversity hotspots, yet less than 10% natural intact vegetation remains. We calculated models projecting the future state of most of these hotspots for the year 2050, based on future climatic and agroeconomic pressure. Our models project an increasing demand for agricultural land resulting in the conversion of >50% of remaining natural intact vegetation in about one third of all hotspots, and in 2–6 hotspots resulting from climatic pressure. This confirms that, in the short term, habitat loss is of greater concern than climate change for hotspots and their biodiversity. Hotspots are most severely threatened in tropical Africa and parts of Asia, where demographic pressure and the demand for agricultural land is highest. The speed and magnitude of pristine habitat loss is, according to our models, much greater than previously shown when combining both scenarios on future climatic and agroeconomic pressure.