Fermented leaf fertilizers (FLF) are made of anaerobically fermented plant and/or animal resources and principally used for foliar plant nutrition, as they provide a quick nutrient supply, especially of micronutrients. Their use is most common in horticultural production as a complementary measure to organic basal fertilization in the case of nutrient deficiencies. Since FLF are commonly made of farm residues, their formulation varies according to the available resources and the treated crops. The most common raw materials are cattle manure, cow milk, cane molasses, and water. Within Latin America, the production of FLF is popular with smallholders. Most of these farmers produce them on-farm using adapted plastic barrels as fermenters. Industrial production is conceivable. FLF have been successfully tested in banana, bean, broccoli, carrot, cucumber, lettuce, maize, papaya, and spinach production. This review highlights the principles of this sustainable and promising organic fertilization strategy, emphasizing the preparation of FLF.

Today, the demand for soybean for feed industry and food production in Germany is met by imports from South and North America. Soybean cultivation in Germany, although challenging, will be of interest in the future due to an increasing demand for non-genetically modified (NGM) soybeans. To meet this rising demand for NGM soybeans and to increase resource use efficiency there is a need to reduce soybean harvest losses arising from harvesting with combine harvester. The height of the first pod can be a major factor affecting harvest losses, especially when it is not possible to maintain a sufficiently low cutting height. From 2011 to 2013, six soybean varieties were cultivated using two cropping systems (conventional ‘CON’ and organic ‘ORG’) at the Osnabru ̈ck University of Applied Sciences in a randomized block design with four replications to investigate the effect of first pod height and plant length on harvest losses and the effect of the cropping system on these parameters. Before harvesting with an experimental harvester, 1.5 m2 per plot were harvested manually as a reference. First pod height, number of pods per plant and plant length were determined on 10 plants per plot. Over the three years of the study, the first pod height (10.4 cm) and plant length (81.4 cm) were on average higher under conventional conditions compared to organic cultivation (7.3 cm; 60.9 cm). On average, lower harvest losses (25.6% vs. 39.2%) and higher grain yields (20.8 dt ha−1 vs. 16.9 dt ha−1) were also observed under conventional cultivation. Varieties differed significantly in grain yield, first pod height and plant length. A high first pod height was related to a longer plant length and lower harvest losses at both sites. However, a high first pod height and a high plant length did not lead to higher grain yields on any of the plots. These results indicate that harvest efficiency can be improved by choosing varieties with long plant lengths if it is not possible to maintain a low cutting height when harvesting with a combine harvester.

Organic farming is often subject of heated scientific and public debates. This raises the question: How can scientists working in organic farming research achieve being impartial while simultaneously sharing enthusiasm about organic farming and promoting it as a solution to many of the problems of agricultural and food systems? Science needs to be unbiased and detached from its object of investigation. It should be hesitant to draw conclusions. Public statements must wait until evidence is strong and reproducible. Complex matters need to be communicated in a differentiated way that acknowledges pros and cons. Finally, science needs to follow a strict separation of facts and opinion. In which ways does this culture go hand in hand with a burning passion for organic farming?