Effect of Different Land Uses on Physical, Chemical and Biological Characteristics of Soil, Plot No. 4, Shahriar, Tehran Province

Soils are one of the largest carbon stores in the biosphere with the highest carbon storage potential to mitigate the effects of climate change. The aim of this study was to investigate different land uses on carbon storage and other physical, chemical and biological characteristics of soil in Shahriar. For this purpose, rangelands including 26-year-old, 16-year-old and 11-year-old Atriplex and 18-year-old Haloxylon, and agricultural lands including rainfed and irrigated cultivation, as well as control lands were selected.

 Soil samples from the depths of 0-10, 10-20 and 20-40 cm were randomly and systematically collected and analyzed. After drying, the soil samples were first passed through a 2 mm sieve and then the percentage of stones and pebbles was determined. Next, soil texture (percentage of soil constituents) by hydrometric method, acidity of saturated soil extract by pH meter, electrical conductivity in saturated extract by EC meter, soil lime by calcimetric method, nitrogen by Kjeldahl method, phosphorus by spectrophotometric method, sodium and potassium were measured by film photometric method, soil organic carbon content was measured by Walkly-Black method, and apparent specific gravity was measured by the clod method. Microbial respiration of soil samples was measured through a closed bottle, carbon and nitrogen of microbial biomass by fumigation-extraction method and metabolic contribution by dividing the released carbon dioxide (mg of carbon per gram of soil per hour) by the microbial biomass of soil carbon (gram of carbon) per gram of soil) was calculated. The microbial contribution was obtained by dividing the two parameters of soil microbial carbon (mg carbon/g soil) by soil organic carbon (g carbon/g soil). One-way analysis of variance (ANOVA) was used to compare soil data among different land uses. . Duncan's test was used to test the difference at the one percent level (p<0.01). All statistical analyzes were performed using the statistical software package SPSS, 19.       

The results showed that the physical, chemical and biological characteristics of the soil were significantly different (p < 0.01) between different land uses, so that the highest amount of carbon storage was related to irrigation treatment of 1.38% and the lowest rate was related to the control treatment of 0.14%. Also, the lowest bulk density is related to irrigated treatment of 1.36 gr/cm3 and the highest amount of basal respiration is related to 18-year-old Haloxylon treatment of 0.73 mg CO2 g−1 day−1. and Also the highest amount of microbial biomass carbon related to irrigated treatment of 124.55 mg g-1 soil. In general, agricultural lands have more potential for carbon storage than other land uses studied in this area. Finally, it should be said that different land uses have a significant effect on the physical, chemical and biological properties of the soil, and play a significant role in the long-term carbon storage in the soil.                                             

This research showed that success in restoring desert areas by using these species depends on knowing the relationship between soil and vegetation. The physical, chemical and biological properties of the soil affect the carbon exchanges between air and soil. The type of vegetation and land use are factors affecting soil properties. This research shows that the most appropriate ways to store carbon in the soil are preventing desertification and deforestation, also preserve and restore vegetation cover.