At the first oral presentation on soil and soil fertility today there were five young scientist presenting their work. I found two very interesting. Steffen Werner from the University of Bochum tried to answer if urban agriculture can contribute to food security by reducing nutrient losses. His two years work in Ghana used biochar and water irrigation to reduce nutrient losses. Urban and peri-urban agriculture is characterized by higher input and soil degradation. Excessive use of mineral fertilizer can lead to losses of nutrient through leaching.

However, his results still showed increased nutrient leaching, especially of N, P, Ca, Mg, and Na. He suggested more appropriate irrigation, because that proved effective in lowering leaching .

Irabella Thiemann from the University of Bonn tried to find out if flow paths in maize-paddy rice cropping system can be a hotspot for nutrient cycling. Maize-paddy rice cropping systems consume less water during the dry season. Changing systems from maize to rice led to desiccation cracks in the soil. Her research studied the role of this crack, where anaerobic conditions lead to methane emissions.

In the AULA, the poster session started with only a handful of patient Tropentag participants as the plenary session dragged on without end. After a few posters were presented, it got more and more crowded, to the point that standing two meters away from the speaker made it impossible to hear, much less understand. Conversations among the gaggle watching made it even harder. Camera and t-shirt made it clear I was there on business, and people made way so I could capture the the main content.

Based on the presented posters during the first session, soil and its components (it's a 4-dimensional object!) play a vital role in sustainable food production and therefore our future. The young researchers tried to find ways to use the many qualities of soil. Vitalij from the Juelich Institute had researched the effects of recycling sugarcane bagasse, a byproduct of industrial processing, when applied in soybean cultivation to increase nutrient availability and uptake.

An Interview with Prof. Dr. Rattan Lal “You cannot continue taking money out from the bank without putting it back. So improvement of soil on the basis of what has been taken out from harvesting must be replaced in a scientific manner,” stressed Prof. Dr. Rattan Lal, a distinguished university professor in soil physics and tropical soils from Ohio State University. Either chemically or organically “Applying manure or using bio-soil is the best option, but sometimes it is not strategically a very good option because manure requires a bulk amount. We require 10 ton/hectare of manure, which is the equivalent to100 kg of chemical fertilizer. So sometimes it is a question of logistics” he added. “A judicious combination of both organic and inorganic fertilizers is required because many times the organic matter is not adequate – it is called integrated nutrient management.” Sub Saharan soils are marginalized “I think Africa is the continent where the green revolution has by-passed because the soils in Sub Saharan Africa are really marginalized. They are depleted, denuded and degraded. Soil erosion and nutrient depletion of soil organic matter content have been very serious problems in Sub Saharan Africa. For sustainability, soil quality must be improved,” he concluded.

Introduction by Dr. Stefan Schmitz: In introducing the session, he said that the talk is focussed on marginality, fragility, uncertainty, instability, food security and rural development. Crisis at the horn of Africa but also experiences from all over the world are major issues of worry and of priority to GIZ. He stated that various aspects of national key sectors come together (e.g cultural, political, environmental etc) and need attention by development agencies. Do all these dimentions of fragility interlink or are they independent? We should link evidence base, research base, scientific base etc., with political situations which is what GIZ is doing. Anneke Trux then spoke on the topic “How can UNCCD and other UN Conventions support and enable sustainable land management in fragile systems?” She started by answering the questions; What is a convention? and What does a convention regulate? She explained that a convention is a treaty among different countries, is an internatinoal legal framework, and that even though it is not a law, partners agree to the terms and aims. A convention regulates strategies, obligations, aims and objectives. She emphasized that since conventions are not laws, the commitment of parties is a major obstacle for implementation.

A bit of background information about Prof. Lal Prof. Rattan Lal is a professor of Soil Science in the School of Environment and Natural Resources at the Ohio State University, USA. He has been involved in several activities both in research and teaching. He is a member of the U.S National Committee on Soil Science of the National Academy of Sciences (1998-2002) and (2007-to date). He is the lead author of the Inter-governmental Panel on Climate Change (IPCC) which earned him the Nobel Peace Prize in 2007. Read more about him at http://senr.osu.edu/facview.asp?id=382 Student reporter : What would be your take home message to someone who is not present here at the Tropentag 2011 conference? Prof. Lal : Several things depend on soil such as food security, water quality, climate change, production and biodiversity. Many ecosystem services which depend on soil are jeopardized because of poor soil management. Taking soils for granted has been the cause of many serious problems and we should avoid it. Student reporter : How can we achieve good production on marginal soils?

Agriculture is a major contributor to global carbon dioxide emission according to Prof. Rattan Lal, distinguished professor at the Ohio State University, USA who presented on marginal soils at Tropentag 2011 . He defined marginal soils as “soils of poor quality and characterized by low ecosystem functions and services”. He also underscored the linkages between soils and the ecosystem and spoke about the importance of soil for humanity. He said that when soils get marginalized, people also get marginalized and that when farming occurs, nutrients are removed and these nutrients must be replaced one way or another, otherwise soils then get marginalized. According to him, if the millennium development goals would be achieved, then soils should be taken more seriously and properly protected. Soil degradation Land is needed for human settlement especially with population growth and urbanization, and Prof. Lal estimates that up to about 400, 000 ha of land is needed per year for one million people which means that about 3 million ha is converted to areas of human habitation each year. Another cause of soil degradation he mentioned is the use of top soil for brick/block making as well as use of soil for sale. He stated that, “soils can provide for our needs but not our greed”.