Ulrich Köpke

Nutrient Management in Organic Farming Systems: the Case of Nitrogen

ABSTRACT Nitrogen management in organic agriculture is discussed focussing on strategies maximizing nitrogen input (source: N2-fixation) and minimizing nitrate losses on-site (field losses) and off-site (losses from manure heaps). Due to a strong relationship between grain yield/amount of N in grains and N2-fixation in pulse-crops or total dry matter yield and N2-fixation in fodder legumes, e.g. grass/clover mixtures, nitrogen fixation can be maximized by selecting the best site-adapted (best yielding) species, varieties or mixtures, respectively. Strategies to reduce nitrate losses are based on N-sinks, that is, plants taking up soil-borne and residual nitrogen during or after growth of legumes efficiently, e.g. brassica-underseeds in faba beans, catch crops, or following crops with great sink capacity for nitrogen. In order to keep pre-winter mineralization as low as possible (minimizing N-source) turn over of grass/clover can be postponed or tillage intensity can be reduced in depth or frequency. Gaseo...

Bio-resource evaluation within agri-environmental assessment tools in different European countries

Abstract In order to achieve environmentally sound agriculture as well as a remuneration of ecological achievements on the farm level, practicable instruments for accurate measurement have to be developed. Whereas there are suitable indicators to assess agricultural impacts on abiotic resources, there is a lack of indicators for the assessment of biotic resources on the farm level. Proposals for and attempts at as well as first-hand experience in assessment methods of agricultural impacts on biotic resources exist in various European countries. A few of these methods require intensive measurements with a lot of indicators, but a sufficient assessment and evaluation of the biotic as well as the aesthetic resources (landscape structure/image) on the farm level has not yet been carried out. Biotic resource indicators of seven assessment methods (Ecopoints Lower Austria, Solagro, Halberg, Nature Balance Scheme, KUL, Frieben, Biodiversity Yardstick) from five European countries are compared with each other. Some of the methods register biotic resources only marginally by indirect measurements (indicators), respectively, or action-oriented indicators such as time of cutting/mowing, frequency of cutting/mowing, age of grassland, percentage of unsprayed area. Other methods are very complex, so that their implementation on a wide scale does not seem possible. There is a need to further develop and improve practicable and efficient tools in order to assess the agricultural impact on bio-resources on farm level and consequently in order to promote an environmentally sound agriculture.

Cotton-basil intercropping: effects on pests, yields and economical parameters in an organic field in Fayoum, Egypt

ABSTRACT In many countries, cotton is traditionally intercropped with other plants in order to increase yields and to control pests. The effects of intercropping cotton (Gossypium barbcidense L.) and basil (Ocimum basilicum L.) were tested during one field season on pest infestation, yields and economical parameters in the Governorate of Fayoum, Egypt. Basil, which is known for its repellent effect on various insect pests, was mixed with cotton in three different intercropping rates (no, medium and high basil area fraction) and two row distances (60 and 90 cm) using a substitutive design with four replicates. Compared with the non-intercropped plots, cotton-basil intercropping significantly reduced total pest infestation and led to a 50% reduced abundance of the pink bollworm (Pectinophora gossypiellci Saund.). Basil affected also the movement and abundance of the beneficial epigeic fauna (e.g., Coleoptera, Araneae, Gryllidae, Salientia). Abundance of the epigeic fauna was 30% higher adjacent to basil strips than in the centre of the cotton plots. Since neither basil intercropping nor different row distances affected microclimatic parameters in the experimental plots, it is assumed that both a basil-induced repellence against pest insects and a stimulation of beneficial epigeic fauna might be responsible for the lower pest infestation observed in intercropped plots. No correlation between pest infestation and cotton yields could be detected. Despite an up to 33% reduced area of cultivated cotton in the intercropped plots, seed cotton yield was not affected by intercropping. The wider row distance significantly reduced the number of cotton bolls per area, but increased boll mass and cotton yield per plant, thus resulting in similar seed cotton yield per hectare than at narrow row distance. The wider row distance also increased the abundance of spiders and crickets but did not affect weed abundance. With the exception of the treatment ‘intercropping with low basil fraction and wide row distance’, higher total revenues and gross margins were determined with intercropping than with cotton monocropping. These results demonstrate the high potential of intercropping cotton with basil in order to achieve a reduced pest infestation while concurrently increasing gross margins for the farmers.

Soil type, management history, and soil amendments influence the development of soil-borne (Rhizoctonia solani, Pythium ultimum) and air-borne (Phytophthora infestans, Hyaloperonospora parasitica) diseases

The impact of soil type, long-term soil management, and short-term fertility input strategies on the suppressiveness of soils against soil-borne (Ocimum basilicum – Rhizoctonia solani, Lepidium sativum – Pythium ultimum) as well as air-borne (Lycopersicon esculentum – Phytophthora infestans, Arabidopsis thaliana – Hyaloperonospora parasitica) diseases was studied. Soils from field trials established in five European sites with contrasting pedo-climatic conditions were examined. Sites included (i) a long-term management field trial comparing organic and conventional farming systems (DOK-trial, Therwil, Switzerland) (ii) a short-term fertility input field trial comparing mineral and organic matter fertilisation regimes (Bonn (BON), Germany) (iii) two short-term fertility input field trials (Stockbridge (STC) and Tadcaster (TAD), UK) comparing the impact of farmyard manure, composted farmyard manure, and chicken manure pellet amendements and (iv) soil from a site used as a reference (Reckenholz (REC), Switzerland). Soil type affected disease suppressiveness of the four pathosystems signficantly, indicating that soils can not only affect the development of soil-borne, but also the resistance of plants to air-borne diseases at relevant levels. Suppressiveness to soil- and air-borne diseases was shown to be affected by soil type, but also by long-term management as well as short-term fertility inputs.

Farm-gate nutrient balance assessment of organic dairy farms at different intensity levels in Germany

Organic farms are characterized as low external input agro-ecosystems. Currently, some organic dairy farmers feed higher amounts of concentrates and succulent feed, some of which is purchased, to increase the dairy performance of their cows. To assess the environ¬mental impact of this practice, nutrient balances at the farm-gate level of 26 organic dairy farms located in two different regions in Germany were compiled and analysed. The farms are characterised by different production features and feeding intensity levels (0 - 2.72 t DM of concentrates per cow and year, which was 0 - 378 g kg-1 milk) yielding 5,150 - 8,790 kg milk on average per cow and year. The area- and product- (milk) related farm-gate nutrient budgets for P and K are almost balanced (mean -3 kg P ha-1, range (R): -14 to 4 kg P ha-1; -0.5 g P kg-1 milk, R: -2.8 to 0.9 g P kg-1 milk and 1 kg K ha-1, R: -13 to 15 kg K ha-1; 0.1 g K kg-1 milk, R: -2.4 to 3.9 g K kg-1 milk). The N surplus averages only 43 kg ha-1 (R: 8 to 85 kg N ha-1) and 8.2 g kg-1 milk (R: 2.1 to 17.1 g kg-1 milk), but the correlation between the amount of feed purchased on a net basis and N surplus is significant (r = 0.56, p = 0.003). Average area-related nutrient use efficiency for all farms calculated as the proportion of input to output is high for N (45%), P (164%) and K (91%). The share of nutrient input and output components and correlations between parameters are presented. To classify the results, investigations comparing organic and conventional dairy farming in Europe are listed, indicating an N surplus for organic farms, which is often only half or a third of the surplus of conventional farms. However, intensification in organic dairy farming has, in some cases, significant impacts that need to be assessed to determine its environmental performance and profile.

Organic Foods: Do They Have a Role?

Nutritional quality is defined as the value of the product for the consumers physical health, growth, development, reproduction and psychological or emotional well-being. This extended definition of nutritional quality can be divided into two terms. One term is for the effects of food determined by its substance, i.e., the sum of all ingredients, beneficial and harmful compounds and their nutritional (or biological) aspects. As a function of inherent inconsistencies ranging from soil and climate differences to effects of cultivars, seasons and agricultural practices, differences in desirable ingredients are less pronounced compared with undesirable ingredients. Where differences are detected, the higher product quality is mostly found in organic produce. A potential advantage of organic agriculture in producing healthy foods is based on higher concentrations of beneficial secondary plant substances in organically grown crops compared to nonorganically grown crops. The second term of nutritional quality covers the feelings of well-being (or indisposition) that certain foods can induce in consumers. Organic agriculture has been confirmed as environmentally sound and more sustainable than mainstream agriculture. Related to this knowledge, the consumers well-being is based on indulgence and the certainty that by purchasing, eating and enjoying organic food, one has contributed to a better future and an improved environment. These effects with their social implications along with improved animal welfare may, in the end, be more important than any measurable contribution of balanced Western diets to individual nutritional health.

Spatial variability of hydrolytic and oxidative potential enzyme activities in different subsoil compartments

The spatial heterogeneity of nutrient turnover in subsoils has been rarely studied in the past, although drilosphere and rhizosphere are found to be important microbial hotspots in this oligotrophic environment. In this study, we measured different potential enzyme activities in different soil compartments of subsoil and topsoil. It could be shown that the activities of hydrolases, which cleave readily available organic substrates, are significantly higher in samples from the drilosphere and rhizosphere both in topsoil and subsoil. In bulk soil, hydrolase activities decrease with depth. In contrast, oxidative enzymes, which are involved in the decay of recalcitrant organic material, are released from the microbial community especially in the bulk fraction of subsoil. This emphasizes the importance of subsoil for nutrient acquisition and gives evidence for a distinct spatial separation of microbes with diverging lifestyles.

Organic Agriculture 3.0 is innovation with research

Organic agriculture can and should play an important role in solving future challenges in producing food. The low level of external inputs combined with knowledge on sustainablity minimizes environmental contamination and can help to produce more food for more people without negatively impacting our environment. Organic agriculture not only includes farming as a production practice but it also includes processing, trade and consumption. Nevertheless, Organic agriculture must always evolve to overcome emerging challenges. Science-based knowledge attained through dedicated research is required to strengthen organic food and farming as a means to solve future challenges. In 2010, a global discussion about Organic 3.0 was initiated to address current problems our agri-food systems are facing. Many scientifically and practically proven results are already available to make organic agriculture a strong tool to solve some of these challenges. However, the organic agri-food system has to be developed further to fulfill its potential. The contribution of organic agriculture to help solve current problems linked to food security and environmental quality was discussed during the International Society of Organic Agricultural Research (ISOFAR) Symposium “Organic 3.0 is Innovation with Research”, held September 20–22, 2015, in conjunction with the first ISOFAR International Organic Expo, in Goesan County, Republic of Korea. Some of the world’s most active scientists in organic agriculture attended the symposium. This paper is a result of their discussions and aims to give an overview of research conducted and required to strengthen organic agriculture in its ambitions to overcome agronomic challenges, contribute to food security and protect our common environment.

Strategies to control Canada thistle ( Cirsium arvense) under organic farming conditions

Three strategies for controlling Cirsium arvense including (i) repeated stubble tillage with subsequent forage crop cultivation, (ii) repeated mowing of a ryegrass–clover ley and (iii) forage crop cultivation following a ryegrass–clover ley ploughed in May/June were investigated in field experiments over 3 years at the Experimental Farm for Organic Agriculture ‘Wiesengut’ in North-Rhine Westphalia, Germany. The development of C. arvense (shoot density, shoot size and ground cover) was regularly assessed on fixed standardized subplots. In the medium-term (9 months), repeated stubble tillage (i) decreased shoot density and regrowth capacity of C. arvense more effectively than a mowed ryegrass–clover ley (ii and iii). However, after 22 months, strategies (i) and (ii) resulted in a similar strong reduction of C. arvense shoot density of 95 and 97%, respectively. At this time, the efficacy of strategy (iii) (89%) was not significantly different to that of strategies (i) and (ii). After 26 months, the effect of all strategies was still apparent; however, the efficacy of strategy (iii) was significantly lower than that of strategy (ii). Generally, the different strategies showed only minor differences, thus delivering options for optimal strategies of thistle control under given specific conditions of sites and cropping systems.

Nutrient cycling in organic farms: stall balance of a suckler cow herd and beef bulls

In organic agriculture, the internal farm nutrient cycle must bequantified to ensure high system productivity accompanied by environmentallysound production processes. In contrast to common farm-gate and field balances,budgeting at the stall level is seldom undertaken. When budgeting mixed farmingsystems, a substantial lack of nutrients can be detected in the “forageand straw input – stall – manure output” nutrient flow chain.Therefore, stall balances focus on a central component of whole-farm nutrientbudgets for developing efficient nutrient management strategies. At theexperimental farm for organic agriculture at Wiesengut in Hennef, Germany, allsolid mass flows for a suckler herd and a herd of beef bulls were measured.Relative balance values obtained for dry matter and C (45 to 56%), N (16to 36%), P (−7 to 22.5%), K (0 to 13%) and ash(−4 to 7%) varied over a wide range. Balances are very sensitive tovariations in mass flow and nutrient content for components with high nutrientcontents and/or a large contribution to total mass flow (e.g. manure, silage).In developing strategies to minimise N losses, by reducing N surplus in theration, one must consider, that, in contrast to dairy farms, a suckler herd forbeef production integrated in an organic farm has to adapt to crop productiondemands.