Student:	Metin Baykara
Supervisor:	Doç. Dr. Ömer KARA
Department:	Orman Mühendisliği
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University Turkey

Title of the Thesis:	EFFECTS OF DIFFERENT LAND USE MANAGEMENTS ON AGGREGATE STABILITY IN ATASU-GALYAN DAM WATERSHED
Level:	M.Sc.
Acceptance Date:	19/6/2013
Number of Pages:	85
Registration Number:	i2678

Summary:

The main purpose of this study was to determine effects of different land use managements

(forest, agriculture, pasture) on aggregate stability in Atasu-Galyan dam watershed, Trabzon. Total

of 180 soil samples were collected from three different land use. The following soil properties were

determined: electrical conductivity, pH, bulk density, particle density, porosity, lime, organic

matter, aggregate stability, microbial biomass carbon and mechanical analyses. According to

obtained data, forest had the lowest aggregate stability (for 1-2mm aggregates) while agriculture

soils had the highest. High aggregate stability in soils under agriculture may be related to high clay

content.

There was not a significant relation between aggregate stability and organic carbon

content. Generally, when the organic matter content is greater than 5-6%, it affects aggregate

stability positively. Below that threshold, aggregation is mainly controlled by clay fraction of soil.

In this study, the mean values for microbial biomass C were 295.6 μg g-1, 376.6 μg g-1, and 383.6

μg g-1 in the agriculture, grassland and forest soils, respectively. One-way ANOVA demonstrated

that forest and grassland soils contain significantly higher microbial biomass C than those in the

agricultural soils. However, there was no significant relation between aggregate stability and soil

microbial biomass carbon (r= 0.148 P> 0.05).

In conclusion, mechanical composition of soil appear to contribute greatly to the stability

of aggregates in humid region. Also, aggregate size that was used in this study (1-2mm), influenced

cementation of soil particles and made clay minerals to be more effective on it rather than organic

matter or biological characteristics of soil.

Key Words: Land Use Managements, Aggregate stability, Microbial Biomass C, Organic C