Using well recorded data of 42 years from a former cattle ranch at the coast of Tanzania, Peter J. Edwards showed impressively how farm management can influence a very fragile ecosystem. Changes in soil nutrient relationships and changes in vegetation mainly due to the grazing and the penetrating bush encroachment of Acacia zanzibarica were the result. Lutz Merbold’s case study in Miombo woodlands of Western Zambia unraveled the Charcoal Trap. An increase in energy demand and the migration of the people to the urban areas for employment call for an increased demand of charcoal since it has a higher energy density and is cheaper for transport. He concluded that the resulting increase of deforestation and thus additional carbon emissions are very large in developing countries. Depending on the resilience of woodlands, the lost carbon from forest degradation may be regained by reestablishment of forests and the consideration of alternative energy sources. The third talk took the audience to India’s coffee production. Virgine Boreux introduced the relationship between bee pollination of three main pollinators identified and the fruit set of coffee plantations. Pollination by bees has a long term impact extending until harvest. The study showed that the fewer sites that are flowering simultaneously, the higher bee abundance was found. In conclusion, irrigation triggering the flowering of the coffee could be used to attract bees. Thus asynchronous irrigation to the monsoon rains can be used in effective plantation management.

Population worldwide is growing, which results in an increasing demand of irrigation and drinking water. During this early morning session solutions for some water management problems in developing countries were discussed. In East-Africa for instance, due to population growth, people are forced to extend agriculture from the high lands into wetlands, where the soil water availability is not constant. Beate Böhme presented that in inland valley wetlands the soil water availability is not very variable and thus very suitable for year-round production. Two other ways to ensure water availability for agriculture in the future are water storage and the use of un-treated wastewater for irrigation. Dr. Irit Eguavoen explained that water storage may be a good option in sub-Saharan Africa regarding climate change, but that the socio-economic impacts for the farmers are large and should taken into account. Phillip Weckenbrock did research in Pakistan to see if the negative image of the use of wastewater for irrigation is justified. He found that the use of wastewater is a very good option for farmers; the wastewater is cheaper to obtain than groundwater and using wastewater results in higher profits. Then Nilhari Neupane and Sisay Demeku Derib presented some local solutions to water scarcity. In Nepal modeling proved that water bargaining by the local population increases the benefits all around. In Ethiopia…

How can we enhance the capacity of smallholder producers to capture benefits from the national and international markets? How can we ensure sustainable management of natural resources? Does decentralization help to fight poverty? These are the major question posed in the morning session ‘rural development’ on 16 September. ‘If we had many gold we would change it to rice, whatever the price it would be’ a testimony of the presentation of ‘Maria Schwab hints on the necessity to consider multiple livelihoods options seriously under market vulnerability and shocks in Cambodia . 'Institutional factors such as land size matters for smallholder to get the benefit of the producers group. Since smallholders do not have required land size to increase the production, collective marketing approach may not work for the benefit to their livelihoods'- are major conclusions of the presentation of Elisabeth Fischer taking the Banana Market in Kenya as a case.//// Village bylaws, a local institutions in Trygary, Ehiopia, enhanced collective action of the users by driving towards common goals in the management of exlosures and resolving conflicts using monetary sanctions. This presentation of Mastewall Yami, highlights that this type of local institutional mechanisms is constrained by high social capital in villages closer to market and district town and resulted in the negligence among users in exposing free riders indicating that high social capital does not always enhance communal resources. ///

Improving Soil Zinc Biovailability in Response to Crop Residues and Wheat Zn Efficient Genotype – Vajiheh Dorostkar Zinc is an important nutrient in the human diet. It is also an important plant micronutrient. Approximately, 50% of land under cereal cultivation is deficient in zinc. These lands are generally located in arid areas. In Iran, where the study was conducted, around 80% of the cultivated land is zinc deficient. Most crop residues are burned or grazed by animals, but residues balance pH, produce organic matter, and improve C:N, etc. As a result, these residues can be used to improve zinc bioavailability in the soil. Crop residues and wheat cultivars were studied to examine their contribution to soil zinc bioavailability in the soil. Sunflower, clover, bean, sorghum and safflower were used in study. The study showed that the use of crop residues from all of the crops have the potential to enhance the zinc bioavailability in arid Iranian agricultural systems. Vajiheh Dorostka gives her presentation on zinc bioavailability and crop residues in Iran Consequences of Sequential Leaf Harvest on Root Yield and N Export of Two Cassava Cultivars in South-central Cameroon – Jelle Willem Duindam

Challenges in feeding the world is not only an issue of production but also an issue of demand, said Christian Nellemann from the United Nations Environment Programme GRID Arendal today at the Tropentag Conference in Zürich. He stated later on that while agriculture surely has impacts on the environment, but more important to understand is how the environment provides the platform for food production. Land degradation and loss of ecosystems services will cost 5-25% of food production by 2050. Some of the causes are considered to derive from uses of pesticides, nitrogen, and phosphate fertilizers which have increased since 1961-1999. Furthermore, the irrigated land today has doubled. Water is also a huge deal of an issue. From the water that we consumed, 75% of it goes to food production. More interesting to realize is that wastewater pollution from ineffective irrigation systems require more water and result in greater run-off, in which we loose 50-70% of N and P.