In this study, a total of 202 surface (0-20 cm) soils were collected from the lands of the producers who made contractual production with private companies in the villages where tobacco cultivation is intensively carried out in the Erbaa district of Tokat province. Basic soil properties, macro phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na) and micro nutrient (Fe), zinc (Zn) copper (Cu) and manganese (Mn) concentrations of soil samples were determined. Spatial distributions of clay content, pH, EC, calcium carbonate, macro and micro nutrient concentrations of tobacco growing lands were modeled using geostatistical methods and spatial distributions were mapped. The coordinates of the sampling locations were recorded using a precise GPS. Soils were mostly neutral and slightly alkaline. Neutral soil pH is desired for sustainable tobacco production. Plants may not be able to uptake some of nutrients in soils with moderate alkalinity. In this case, the use of acid character fertilizers is recommended. All of the macro nutrients are at sufficient levels in the tobacco growing lands. Copper and iron concentrations were at sufficient levels in all fields. Plant available manganese was sufficient in almost half of the sampled lands, while it was insufficient in the other half. Available zinc concentration was well below the sufficient level in most of the lands. In order to increase the production to the desired level, fertilizers should be applied based on the plant requirement and soil analysis results. The registration of the soil sampling locations provides an opportunity to create a very useful database for researchers, producers and suppliers who want to understand how the quality of the tobacco growing lands has changed over time.

With the object to evaluate in the soybeans crop behavior in the interaction of Rhizoctonia solani, vesicular-arbuscular mycorrhizae (VAM) and fungicides used to treatment of seed, two different soil preparations were used in the field trials: natural and chemically disinfected (Ditrapex-CE) and under greenhouse: using vapor- sterilized. Was utilized the fungicides Propamocarb, SN-84364, PCNB y Vitavax- 300. Be had into account the natural mycorrhizal flora and a source of Glomus manihotis introduced. R. solani reduced the emergence of soybean by 50%, the above-metioned pathogen was more agressive in disinfected soil. In the 15 days first the attack increased and reduced the VAM development in the natural soil. With the age of the plant the pathogen infection decreased. With relation by VAM is contrary the tendency. The presence of VAM, G. manihotis including, not increased significantly the dry mass and yield of the soybean. The fungicides diminished the VAM infection in both chemically and physically disinfected soil, whereas this does not ocurr in natural soil,SN-84364, on the other hand, increased the VAM infection. This product affected least the simbiosis in the disinfected soil. SN-84364 and PCNB exhibitited their great especifity against R. solani and Vitavax-300 a greater spectrum of action. | En el campo se dispuso de dos preparaciones de suelo: natural y desinfectado químicamente (Ditrapex-CE) y en el invernadero de suelo esterilizado con vapor. Se utilizaron los fungicidas Propamocarb, SN-84364, PCNB y Vitavax-300. Se contó con la flora micorrizógena natural y una cepa introducida, Glomus manihotis. R. solani disminuyó en un 50 % la emergencia de la soya, comportándose más agresivo en suelo desinfectado. En los primeros 15 días su ataque se incrementó y redujo el desarrollo de MVA en suelo natural. Al avanzar la edad de la planta decreció su infección. Con relación a la MVA la tendencia es contraria. La presencia de la MVA, incluyendo G. manihotis no incrementó significativamente la materia seca y el rendimiento de la soya. Al desinfectar el suelo los fungicidas afectaron negativamente la infección micorrizógena, mientras que en suelo natural no sucedió este fenómeno, al contrario SN-84364 incrementó su presencia. Este producto es el que menos afecta la simbiosis en el suelo desinfectado. Los fungicidas SN-84364 y PCNB mostraron gran especificidad contra R. solani y Vitavax-300 mayor espectro de acción.