Determination the Effects of Land Use Change and Soil Type on Some Quality Properties of Soil Along a North - South Transect ( Case Study Miami County of Semnan Province )

Numerous studies have shown that agricultural soil quality evaluation is essential for economic success of agricultural products and environmental stability in rapidly developing regions. Changes in soil quality characteristics are usually controlled by intrinsic factors such as climate, parent rock and time and dynamic factors (Managerial).For this purpose, evaluation of parameters of soil quality plays an important role in assessing the land management and sustainability of production agricultural systems. The present investigation was undertaken to identify sensivity soil quality parameters against to changes of soil type(foure soil orders inculded, Entisol, Inceptisol, Aridisol and Molisol) and land use(Three land use included, pastureland, forest and agriculture) along a north-south transect with different heat and humidity regimes.

The present study was performed in lands of Miami city in Semnan province. The 215 soil samples collection were done in both natural lands (forest and pastureland) and closest from agricultural lands in three different regions along a north-south transect from 0-30 cm depth and in total of 13 soil parameters including physical, chemical and microbiological properties(EC, pH, O.C, T.N.V, CEC, Urease, Betaglocsidase, phosphatase enzymes, Microbial Biomass Carbon, MWD, BD) were determined. Then, in order to determine the effect of land use change and soil type on the studied soil parameters, the statistical methods of principal component analysis (PCA), factor analysis (FA) and regression were used.

The results showed that most of the chemical, physical and biological properties of soil in the northern lands are better than the southern ones due to changes in humidity and temperature regimes (more rainfall and lower temperatures). The trend of the coefficient of variation of most soil features in the three areas studied along the transect shows that the coefficient of variation of most of the studied features is influenced by climate and the coefficient of variation of most parameters has decreased from south to north, which is probably due to the buffer effects of soil organic carbon in the northern regions. Also the results of PCA and FA analysis showed that organic carbon , betaglucosidase enzyme , microbial biomass carbon , MWD and microbial biomass carbon/ organic carbon had higher weight than other soil quality parameters in all of the regions. Also the results of the statistical method of regression study showed, two factors of land use change and soil type can predict more than 55% changes in most soil quality parameters and the total of 14 properties have been investigated , 10 characteristics were relatively controlled by land use type and 4 characteristics by soil type.

Overall, the results of this study showed that the two factors of land use change and soil category, except for electrical conductivity, soil reaction, absorbable potassium, cation exchange capacity, and calcium carbonate equivalent, have the greatest effect on changes in soil quality characteristics and physical and biological of soil affected by land use change and chemical properties were affected by soil typ therefore, in order to study the effects of management changes on soil quality attributes , biological and physical parameters are more suitable in the short term.