Organic Farming

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?

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.

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.

The nitrogen supply can be a yield-limiting factor in organic farming, especially when reduced tillage is applied. An organic field experiment was conducted from 2007 to 2013 to analyse the potential of the nitrogen supply through the efficient use of green manure crops in different tillage systems. Three farming systems were compared: a stubble cleaner system (SC) and a plough system (PL), both in a cereal-based crop rotation, and another plough system in a crop rotation that included alfalfa grass ley (PLALF). In the fifth year of the experiment, the experimental design was extended into a split plot design, and seven green manure treatments (Lolium perenne, Phacelia tanacetifolia, Sinapis alba, a mixture of Sinapis alba and Trifolium resupinatum, Trifolium resupinatum, Vicia sativa, and bare fallow as the control) were integrated into each of the three systems. The effects of the three systems and the green manure treatments on N mineralization, the soil microbial biomass and the yield of the main crops of oats and field beans in the sixth and seventh years of the experiment were analysed. The results showed that the choice of green manure species was of minor importance in the PLALF system. This system generally success- fully supplied N to the oats with oat yields from 3.6 to 5.1 t per ha.Vicia sativa was the most promising green manure crop in the SC and PL systems, with the Nmin values and oat yields (4.0 and 4.6 t per ha) being similar to those in the PLALF system. In the subsequent year, the PLALF system again was more successful in most of the Nmin assessments than the PL and SC systems, which often had rather similar results. In addition, a main crop of field beans was able to compensate for the differences in the Nmin content, and the yields were similar in all three systems (3.1 to 3.7 t per ha). The microbial biomass in the top soil was significantly increased in the reduced tillage system compared to the plough systems. In conclusion, reduced tillage in organic farming can promote soil microorganisms and be competitive if the nitrogen supply is improved through the efficient use of green manure or an adequate leguminous main crop.

In Belgium and The Netherlands, bread wheat (Triticum aestivum L.) is getting attention within a growing movement looking for more sustainability of wheat cropping and breadmaking. The few varieties available are pure lines that do not match the wide range of environments and organic farming practices, so that yields and milling quality are often disappointing. Composite Cross Populations (CCP) have been created with the idea of evolutionary plant breeding through on-farm mass selection and seed saving. In 2015–2016, one such CCP of winter wheat was cropped side by side with a pure line variety in four organic farms with different wheat cropping practices, as a first step to answer some of the concerns arising from farmers’ networks we work with. Seeding rates ranged from the standard high to the very low ones practiced under the System of Wheat Intensification (SWI). Multivariate data analysis confirmed greater differentiation of the CCP both compared with pure line varieties and within populations on farms where inter-plant competition was less intense. Low seeding rates thus seem to enhance the phenotypic expression potential of a CCP, yet this is a neglected fact among participatory plant breeders. Since both CCP and SWI have great potential for ecological intensification within organic farming, we argue that more work is needed on finding new ways of combining innovation in farming practices and on-farm plant breeding, which also implies new ways of organising research.