Soil chemical and microbial parameters are commonly used as soil quality indicators to evaluate sustainable land management in agroecosystems. The objective of this research was to evaluate the impact of organic and conventional management strategies on biological, chemical and yield parameters in vineyards (Vitis vinifera cv. Sultani seedless). Organic plots received a mixture of barley, vetch and broad bean (25+35+75 kg seed ha^− 1) as green manure, and farmyard manure (15 t ha^− 1) every year. Inorganic fertilizers (NPK) and pesticides were used in the conventional managed vineyards. Conventional and mulch tillage methods were used in conventional and organic plots, respectively. Microbiological and chemical soil properties were determined in the soil samples which were taken four times in 2004, 2005, 2006 and 2007. In addition, the yield and some quality parameters of vineyards were also determined. Soil microbial biomass, and dehydrogenase, β-glucosidase and alkaline phosphatase activity were significantly higher in organic management than in conventional management. Higher C_mic/C_org and lower qCO₂ values were found with the organic management. The response of the chemical indicators (C_org, N_t and available nutrient content) of the soils to different management systems appeared after a longer time than with the biological indicators. In the transition zone between continental and Mediterranean climates of West Turkey, soil quality of organically managed vineyards improved after 2 years of the transition period prescribed for organic certification. However, soil quality improvements in organic plots did not result in higher yield.

Main characteristics of tobacco waste generated during the processing of tobacco for cigarette manufacture are a high content of nicotine and total organic C. Composting is a way for decreasing the levels of nicotine and total organic C in tobacco waste and for disposal of this kind of agro-industrial waste. Changes in pH and electrical conductivity and activities of dehydrogenase, protease, alkaline phosphatase and β-glucosidase were determined during composting of tobacco waste (TW) and mixtures of TW + grape pomace (GP) and TW + olive pomace (OP). The nicotine in the tobacco waste was completely decomposed by composting. In the final composts, total organic C content and C : N ratio decreased, whereas the contents of total N, P and K increased. The pH of the composts increased rapidly at first and then more slowly and the electrical conductivity first decreased and then increased during composting. Mixing the tobacco waste with the other compost materials decreased the electrical conductivity level by 32 and 46% in the final TW + GP and TW + OP composts, respectively. The highest activities of the studied enzymes were observed on the third week of the composting process for dehydrogenase, the fifth week for protease and β-glucosidase and the ninth week for alkaline phosphatase. All enzyme activities stabilized about in 4 months.

In order to assess the suitability of sludge application for maize (Zea mays L.) soil ecosystems, this study aimed to evaluate soil microbial properties over three consecutive years using treated municipal sewage sludge (TSS) amendment in the Typic Xerofluvent Mediterranean soils of Turkey. Soil microbial properties and biochemical activities significantly increased with increasing TSS amounts. Microbial biomass carbon peaked following amendment with 30 Mg ha⁻¹ a⁻¹ of TSS, while basal soil respiration was not significantly affected by TSS doses. Moreover, soil enzyme activity increased significantly with increasing TSS amounts. A significant increase in the grain yield of 7% and 9% was found with 10 and 20 Mg TSS ha⁻¹ a⁻¹ applications respectively, whereas a significant decrease of 5% was found with 30 Mg TSS ha⁻¹ a⁻¹. Our results suggest that if the goal is to achieve plant yield in the short-term, it seems that TSS application of 20 Mg ha⁻¹ a⁻¹ can be recommended as organic fertilizer without causing potential risks. On the other hand, if the primary aim is to ensure the sustainability of the soil organic matter, the use of TSS as organic soil conditioner at a rate of 30 Mg ha⁻¹ a⁻¹ can be recommended.