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TuberLog und Co. – Messverhalten künstlicher Früchte im Labor
Künstliche Früchte werden eingesetzt, um Stoßbelastungen bei der Ernte und Aufbereitung von empfindlichen Produkten zu detektieren. Für die realistische Erfassung der Stoßbeschleunigung sollten die Messkörper den Produkten möglichst ähnlich sein. Hier werden Ergebnisse von Fallversuchen und von Messungen in einer Laborförderstrecke mit verschiedenen elektronischen Früchten sowie eines in eine Kartoffel implantierten Sensors vorgestellt. Die Messsysteme TuberLog, IRD und Mikras sind nach dieser Untersuchung in ähnlicher Weise geeignet, kritische Stellen in einem Aufbereitungsprozess zu detektieren. Beim Aufprall auf feste Unterlagen wird die Stoßintensität durch die verwendeten Messkörper aus Kunststoff im Vergleich zur Messung im echten Produkt überbewertet.
Yield trends, variability and stagnation analysis of major crops in France over more than a century
France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French départements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years. Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved – mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990’s for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.
Comparison of electronic fruits for impact detection on a laboratory scale
Mechanical loads cause severe damage to perishable agricultural products. In order to quantify the mechanical impact during harvest and postharvest processes, several electronic fruits have been developed. The objective of the work described here was to compare on a laboratory scale different types of impact acceleration recording electronic fruits: Mikras implanted in a real potato tuber as well as in a dummy tuber, IRD, Smart Spud and TuberLog. The acquisition of mechanical impacts was performed using a drop simulator with optional steel or PVC as impact material as well as a processing line simulator. Our results show that drops from 10 cm height on PVC caused similar peak accelerations of Mikras implanted in a real potato or a dummy, IRD and TuberLog. When dropped onto steel however, IRD, TuberLog and Mikras implanted in a dummy recorded higher peak values than Mikras in real potatoes. Impact on the flat side of a tuber led to higher peak values than impact on the apical region. This could be caused by different elastic compliance of synthetic materials as well as material thickness. Running through the processing line simulator TuberLog recorded the most impact; Smart Spud recorded a low number of impacts compared to the other electronic fruits. In all experiments the least sensitive measurements were recorded using Smart Spud.