An agent based model representation to assess resilience and efficiency of food supply chains.

Trying to meet the Sustainable Development Goals is challenging. Food supply chains may have to become more efficient to meet the increasing food requirement of 10 Billion people by 2050. At the same time, food and nutrition security are at risk from increasingly likely shocks like extreme climate events, market shocks, pandemics, changing consumer preferences, and price volatility. Here we consider some possibilities and limitations regarding the improvement of resilience (the capacity to deal with shocks) and efficiency (here interpreted as the share of produced food delivered to consumers) of food supply chains. We employ an Agent Based Model of a generic food chain network consisting of stylized individuals representing producers, traders, and consumers. We do this: 1/ to describe the dynamically changing disaggregated flows of crop items between these agents, and 2/ to be able to explicitly consider agent behaviour. The agents have implicit personal objectives for trading. We quantify resilience and efficiency by linking these to the fraction of fulfilment of the overall explicit objective to have all consumers meet their food requirement. We consider different types of network structures in combination with different agent interaction types under different types of stylized shocks. We find that generally the network structures with higher efficiency are also more sensitive to shocks, while less efficient network types display more resilience. At first glance these results seem to confirm the existence of a system-level trade-off between resilience and efficiency similar to what is reported in business management and ecology literature. However, the results are modified by the trading interactions and the type of shock. In our simulations resilience and efficiency are affected by 'soft' boundaries caused by the preference and trust of agents (i.e., social aspects) in trading. The ability of agents to switch between trading partners represents an important aspect of resilience, namely a capacity to reorganize. These insights may be relevant when considering the reorganization of real-life food chains to increase their resilience to meet future food and nutrition security goals.

Olivine weathering in soil, and its effects on growth and nutrient uptake in Ryegrass (Lolium perenne L.): a pot experiment.

Mineral carbonation of basic silicate minerals regulates atmospheric CO(2) on geological time scales by locking up carbon. Mining and spreading onto the earth's surface of fast-weathering silicates, such as olivine, has been proposed to speed up this natural CO(2) sequestration ('enhanced weathering'). While agriculture may offer an existing infrastructure, weathering rate and impacts on soil and plant are largely unknown. Our objectives were to assess weathering of olivine in soil, and its effects on plant growth and nutrient uptake. In a pot experiment with perennial ryegrass (Lolium perenne L.), weathering during 32 weeks was inferred from bioavailability of magnesium (Mg) in soil and plant. Olivine doses were equivalent to 1630 (OLIV1), 8150, 40700 and 204000 (OLIV4) kg ha(-1). Alternatively, the soluble Mg salt kieserite was applied for reference. Olivine increased plant growth (+15.6%) and plant K concentration (+16.5%) in OLIV4. At all doses, olivine increased bioavailability of Mg and Ni in soil, as well as uptake of Mg, Si and Ni in plants. Olivine suppressed Ca uptake. Weathering estimated from a Mg balance was equivalent to 240 kg ha(-1) (14.8% of dose, OLIV1) to 2240 kg ha(-1) (1.1%, OLIV4). This corresponds to gross CO(2) sequestration of 290 to 2690 kg ha(-1) (29 10(3) to 269 10(3) kg km(-2).) Alternatively, weathering estimated from similarity with kieserite treatments ranged from 13% to 58% for OLIV1. The Olsen model for olivine carbonation predicted 4.0% to 9.0% weathering for our case, independent of olivine dose. Our % values observed at high doses were smaller than this, suggesting negative feedbacks in soil. Yet, weathering appears fast enough to support the 'enhanced weathering' concept. In agriculture, olivine doses must remain within limits to avoid imbalances in plant nutrition, notably at low Ca availability; and to avoid Ni accumulation in soil and crop.

No evidence for substantial aerobic methane emission by terrestrial plants: a 13C-labelling approach.

* The results of a single publication stating that terrestrial plants emit methane has sparked a discussion in several scientific journals, but an independent test has not yet been performed. * Here it is shown, with the use of the stable isotope (13)C and a laser-based measuring technique, that there is no evidence for substantial aerobic methane emission by terrestrial plants, maximally 0.3% (0.4 ng g(-1) h(-1)) of the previously published values. * Data presented here indicate that the contribution of terrestrial plants to global methane emission is very small at best. * Therefore, a revision of carbon sequestration accounting practices based on the earlier reported contribution of methane from terrestrial vegetation is redundant.

[Photo-thermal characteristics of a non-photosensitive and extra-premature winter wheat variety].

In a sowing by stages test with winter wheat variety Jingdong 8 (JD8) as reference, this paper studied the photothermal characteristics of a non-photosensitive and extra- premature winter wheat variety Dongzao 5 (DZ5), and the effects of sowing stages on its growth and yield. The results showed that the harvest date of DZ5 was 4-5 days earlier than that of JD8, and its yield with standard sowing date increased by 43.4%. In addition, DZ5 had a shorter thermoperiod for ear differentiation, and didn't need strict vernalization process and photoperiod, which could be sown either before or after winter.

Hydrodynamics of burst swimming fish larvae; a conceptual model approach.

Burst swimming of fish larvae is analysed from a hydrodynamic point of view. A picture of the expected flow pattern is presented based on information in literature on unsteady-flow patterns around obstacles in the intermediate Reynolds number region. It is shown that the acceleration stage of burst swimming under restricted conditions can be treated as a frictionless impulsive motion. The stream pattern resulting from this motion is presented and the efficiency of locomotion during the acceleration stage is calculated. The flow pattern in the post-acceleration stage is sketched and the origin of an interaction between the viscous and the reactive force contribution to the propulsive force in this stage is discussed. It is explained how this interaction can lead to an increase in propulsive efficiency. A conceptual model is developed describing the three stages in burst swimming locomotion: the acceleration stage, the post-acceleration stage and the gliding stage. Data from literature of the travel distance versus time relation of the common carp larva (Cyprinus carpio) of 5.5-mm length has been used to test the model results. The test appeared remarkably successful, and the model results for larger larvae up to 22 mm length are presented. The gliding distance as a function of larval length resulting from the model has been compared with experimental data from literature.