• Energy Research

Many scientific disciplines currently are experiencing a “reproducibility crisis” because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that the deliberate introduction of controlled systematic variability (CSV) in experimental designs can increase reproducibility. We tested this hypothesis using a multi-laboratory microcosm study in which the same ecological experiment was repeated in 14 laboratories across Europe. Each laboratory introduced environmental and genotypic CSV within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV led to lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility also was lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the “reproducibility crisis”, deliberately including genetic variation may be a simple solution for increasing the reproducibility of ecological studies performed in controlled environments.

Inherent in the concept of good agricultural practice (BMP) is that it improves resource use efficiency, mitigates environmental impact or increases farm profitability. However, it is usually impossible to achieve all the objectives, and trade-offs need to be accepted, such as a reduction in productivity together with a reduction in costs or an increase of soil organic matter. A European FP7 project, Catch-C (http://www.catch-c.eu) analyses the effects that different management practices have on productivity, mitigation of climate change and chemical, physical and biological soil fertility, based on simple indicators. Such indicators were collected from international literature, national scientific or technical journals, or grey literature that dealt with long-term field trials in Europe. We collected and analysed data from more than 350 experiments. This paper presents the overall results of the effects of a series of BMP have on crop productivity, soil nitrogen (N) uptake, N use efficiency end N balance. Important interactions with soil and climate types, crop and duration of the experiment were noticed for most BMPs. Rotations, also including double cropping, were among practices with more positive effects of productivity and N indicators. A slight reduction of yield counteracted benefits to soil quality and to climate change mitigation of minimum and no tillage, and of organic fertilisers.

Abstract Energy efficiency of agriculture needs improvement to reduce the dependency on non-renewable energy sources. We estimated the energy flows of a wheat–maize–soybean–maize rotation of three different cropping systems: (i) low-input integrated farming (LI), (ii) integrated farming following European Regulations (IFS), and (iii) conventional farming (CONV). Balancing N fertilization with actual crop requirements and adopting minimum tillage proved the most efficient techniques to reduce energy inputs, contributing 64.7% and 11.2% respectively to the total reduction. Large differences among crops in energy efficiency (maize: 2.2 MJ kg−1 grain; wheat: 2.6 MJ kg−1 grain; soybean: 4.1 MJ kg−1 grain) suggest that crop rotation and crop management can be equally important in determining cropping system energy efficiency. Integrated farming techniques improved energy efficiency by reducing energy inputs without affecting energy outputs. Compared with CONV, energy use efficiency increased 31.4% and 32.7% in IFS and LI, respectively, while obtaining similar net energy values. Including SOM evolution in the energy analysis greatly enhanced the energy performance of IFS and, even more dramatically, LI compared to CONV. Improved energy efficiency suggests the adoption of alternative farming systems to reduce greenhouse gas emissions from agriculture. However, a thorough evaluation should include net global warming potential assessment.