From "Reports on Agriculture", Exercise number 1, May 2009

Concepts for a more efficient use of phosphorus based on experimental observations


  1. The fertiliser industry predicts a sinking rock phosphate production all over the world after the peak production point had been hit in the 1980/1990’s. The global P reserves with the currently applicable evaluations (physical, chemical characteristics) and accepted costs for exploitation and processing are expected to last for only approx. 120 more years, reserves of lower quality and higher costs about three times longer. An acute lack of phosphate fertiliser does therefore not yet exist. But phosphate prices have increased by 300% over the last two years. This is a clear signal, for phosphate consumers in particular, to exploit the unused potential in agricultural soil and handle this limited resource in a more efficient way.
  2. More recent results of long-term P field experiments in different German regions show that approx. 4mg P/100g lactate soluble phosphorus are fully sufficient for high yields, in Bavaria content class B (2-4mg CAL-P/100g soil) with fertilisation equalling crop removal. In the light of these results, we must very critically examine the system of five content classes dating back to 1997, and the margin of content class C (4-9mg P/100g soil) in particular, as with an initial content of 4mg P/100g soil (content class B/C) it would need approx. 500kg P/ha (i.e. an amount of P equivalent to the removal of about 20 harvests) to reach 9mg P. With prices up by 300 percent (compared to 2005), this cannot be recommended.
  3. In Germany, 2.4 million tonnes of dry matter sewage sludge (approx. 2 percent P) with approx. 48,000 tones of P, 400,000 tonnes of animal meal (approx. 12,000 tones of P) and 160,000 tonnes of meat-and-bone meal (approx. 9,600 tonnes of P) are disposed of as waste every year. Current P consumption in the form of phosphate fertiliser amounts to 108,000 tonnes of P per year. With a P recycling rate of 90 percent, more than 50 percent of the currently imported mineral fertiliser P could thus be replaced. In 2004, the Federal Ministry of Education and Research (BMBF) and the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) began to support research and innovation in P recycling. First methods for the production of new P fertilisers are currently being developed and P fertilisers are being tested. First agronomical tests of potential new P fertilisers have already been carried out.
  4. P dynamics in the soil are very complicated as phosphate is subject to specific anion adsorption and precipitation by calcium ions in particular. Whereas grain crops handle the low P concentrations in the soil solution with their extensive root system (rye e.g. 38 km/m2), dicotyledons excrete a series of organic acids (citrate, malate, oxalate) which mobilise phosphate in the rhizosphere through ligand exchange to make it absorbable. The latter principle is, for example, used by eucalypt plants in Japan (51). Gene transfer is regarded as a way to indirectly increase the P absorption efficiency of plants. An important method without gene transfer lies in the breeding with a view to high P absorption efficiency by way of marker-assisted breeding with QTLs for P absorption. This method had already been successfully adopted within the scope of a rice project in Japan/India (58; 59).
  5. The internal P utilisation of arable crops (kg dry-matter production/g absorbed P) obviously has a considerable range of variation. It can therefore also be said in this respect that the P absorption efficiency of the plants can still be increased considerably.
  6. The possibilities to apply fertilisers according to the actual needs should be fully exhausted and the use of P fertilisers should be adjusted to the specific site conditions and cropping ratios.

Use of the milk urea content in feeding advice and as an indicator of the N excretion in milk production - an overview


The aim of this overview is to show possibilities for improving the N utilization and thereby reducing N secretions by dairy cows from the point of view of feeding and breeding.

The milk urea content which has so far only been used for the optimization of feeding as an "auxiliary quantity" in praxi should be used more frequently in future in terms of its information content about the urine N- excretion.

The milk urea content represents a valuable indicator for the N excretion on a farm. It could in addition be used in future as an animal-specific 'environmental' indicator (for the N excretion) in breeding (after a further genetic statistical processing of existing data).

Key words: Dairy cow, milk production, milk urea content, animal-specific indicator, MUN (=milk urea N)

Integrated biogas and solid fuel production from whole crop silages


With the "Integrated generation of solid fuel and biogas from biomass (IFBB)", which has been developed at the University of Kassel, a solid fuel is produced from ensiled biomass using mechanical dehydration; in terms of quality, this fuel lies between wood and unprocessed agricultural crops. The mechanical dehydration causes a very high transfer of minerals and mobile parts of the organic matter into the press fluid. This press fluid is then fermented to biogas. The press cake, which is rich in lignin and cellulose, is dried to make a storable solid fuel. Using maize silage as an example, it was demonstrated that hydrothermal conditioning (mashing) increases the mass flows of dry matter and minerals into the press fluid. Mashing with cold water resulted in the highest dry matter content in the press cake and simultaneously in the highest mass flows into the press fluid. The substitution of water with mashing fluid for the purpose of conditioning, a method which could reduce the water consumption of the process, produced contradictory results and needs further investigation. Energy balances for the IFBB process produced higher values for conversion efficiency than for traditional biogas production from whole-crop silages.

Increase of area under silage maize as a result of the "biogas-boom" – A risk for farmland birds?


Due to the continuously increasing number of biogas plants in Germany, the area cultivated with silage maize Zea mays has been increasing significantly over the past few years. From the viewpoint of nature conservation it is generally supposed that this change in land use could result in losses of habitats of wild plant and animal species. In this paper we present the results of a study conducted in the federal state of Schleswig-Holstein in Northern Germany over the period 2005 to 2007. Paired comparisons of single arable fields were used to analyse whether silage maize fields were characterized by other bird communities than fields cultivated with common cash crops (winter cereals, winter oilseed rape). Birds were recorded during the breeding time as well as during the non-breeding time.

Maize fields and cash crop fields showed similar numbers of breeding bird species. Lapwings Vanellus vanellus occurred more often in maize fields, whereas Yellow wagtails Motacilla flava occurred more frequently in reference fields grown with cash crops. The abundance of Skylarks Alauda arvensis, however, was not affected by the cropping system. During the non-breeding periods, there was no difference in the number of bird species either. However, the total bird density was higher on fields where maize had been cultivated directly beforehand or subsequently than on reference fields.

The results indicate that in areas, which are dominated by winter sown crops, the effects of increased production of energy maize have to be assessed specifically for each bird species. A literature survey on the breeding biology of bird species recorded in our study, however, revealed that maize fields are often characterized by poor breeding success of birds, which is attributed to low vegetation cover and to low feed supply on maize fields during the breeding period. Results obtained during the non-breeding periods indicate that a substitution of winter crops by maize could improve the feed supply for resting birds and hibernating birds, respectively. However, these effects probably just occur if crop residues or stubble remain on the fields prior to the cultivation of maize or subsequently.

Future studies on the actual effects of energy maize cultivation on bird life should consider the landscape-level as well as alternative reference systems, especially grassland areas.

The effect of price increases of heating oil on horticultural companies in Saxony. Part I: Initial energy situation of glasshouse companies


Small glasshouse companies predominate in Saxony, Germany, where they lack state-of-the-art technical equipment and have higher energy costs compared to large greenhouses. From an economic point of view, the horticultural glasshouse companies in Saxony, which mostly cultivate ornamental plants, show an unclear picture. Aside from the relatively higher expenditures compared to companies in other federal states of the Federal Republic of Germany, companies with indirect marketing approaches have sustained slumps in expected turnovers.

The initial conditions for adaptive measures of several horticultural companies are estimated to be difficult or very risky due to the economic climate. Large-scale and capital-intensive modernizations of many companies will not be feasible without an intense promotional campaign.
With regard to this study, many parts of greenhouses in Saxony are not optimally equipped in terms of energy consumption. Most of those built are an older type of greenhouse known as a German standard greenhouse. Heating oil is the most frequently used energy source, followed by natural gas and coal/coke in Saxony. Up to now, biomass materials have only been used to a minor extent.

Therefore, it is necessary to examine feasible measures that are energy- and cost-efficient for existing companies in Saxony. Furthermore, the question remains as to which heating systems/heat supply concepts should be regularly used by boilers or greenhouses in the future. An answer to these questions can be found in the second part of this paper.

Farmers’ and Experts’ Knowledge and Image of Farming Cooperatives: A Comparison of the Two Groups


In two surveys, farmers as well as teachers and consultants (experts) in German-speaking Switzerland are questioned as to their knowledge of farming cooperatives and the image they associate with them. Both farmers and experts gauge their own standard of knowledge as meagre, particularly with regard to financial arrangements or conditions for disbandment. Nevertheless, experts in general know more about farming cooperatives than the farmers interviewed. The image farmers have of farming cooperatives is not particularly positive, with interpersonal conflicts as well as a situation of high dependency being viewed as the main drawbacks. There is a positive correlation between knowledge and image in the farmers’ group. In the experts’ group, this correlation fell just short of significant. Increased efforts to disseminate information could thus improve the farmers image of farming cooperatives. The fact that the experts have a significantly better image of the farming cooperative would support this. One of the challenges faced here is the modest flow of information between experts and farmers.

Information exchange between different stages in the meat supply chain: Legal framework and certification as determining factors


Strengthening competitiveness in an increasing dynamic market environment poses a continuous challenge for companies in the meat sector. In this regard, market participants are confronted with the task of providing customers’ confidence in the quality and safety of the products offered. Whereas public authorities have reformed European food law, the players in the meat sector have reacted by implementing numerous systems to certify their products and processes. According to the prevailing assumption that chain-wide communication is a critical success factor for supply chains in agribusiness, this paper analyses the relevant legal norms as well as certification systems in the pork production sector whether they support the necessary information exchange between supply chain partners. It can be stated that currently both legal norms and certification systems support the necessary information flow only in a very limited manner. The presented findings emphasize the necessity of a comprehensive and practicable information system in meat production. Finally, the results lead to a discussion about future requirements for the design of chain-wide communication systems.

Food quality from the consumer perspective - a synthesis of qualitative studies about consumers’ perception and assessment of individual quality criteria of organic products


Although the importance of organic food has increased continuously during the last years, the organic market share is still relatively low. This is remarkable because organic food meets many consumer expectations regarding food quality and safety, and health. However, consumers rather prefer individual attributes of the complete organic agricultural system, such as animal welfare or the non-use of chemical fertilisers and pesticides, than the organic production system as a whole. In the present article, a synthesis of three explorative studies about the reasons for the preferences of individual attributes as well as for the still low market share of organic food are presented. Within the synthesis of the three studies, similarities and differences from the 10 focus group discussions were identified in order to derive comprehensive results describing the relevance of individual food attributes and organic food.

The preference of individual quality attributes of organic food compared to the complete organic agricultural system is mainly explained by the nature of consumer perception, which is a selective system of information collection and assimilation. Thus, the communicability of complex circumstances, such as organic farming or food quality, is very limited. Furthermore, the synthesis showed that the consumers’ examination of food is predominantly focussed on the last step of the food production process, which has consequences for the communication policy of organic food on product level.


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