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