Effect of Agronomic Practices on the Aggregate Stability and Organic Carbon of soil (Case study: the Northern of Aq Qala)

Soil is accounted as a large sink for the atmospheric carbon dioxide. Carbon dioxide emission from soil will increase by operations such as land-use change, biomass and fuel combustion, industrial production as well as tillage. Operations like tillage could accordingly intensify the soil biological activity, which per se leads to more carbon emission to atmosphere. Thus, utilizing the methods ofseedbed preparation that cause low soil disturbances (conservation tillage) will prevent carbon emissions from the soil to the atmosphere; that in turn increases the content of soil organic matter; consequently, soil aggregate stability improves, against erosive factors. The research aims to assess the effects of different tillage systems (no-tillage, low tillage and conventional tillage) on the organic accumulation and the aggregate stability of the soil. The appropriate soil management and farming practices could exert a great positive influence upon crop yield. The study area is located in the eastern of Aq Qala, Iran. Three treatments of tillage systems, namely, traditional management, no-tillage and low tillagehave been examined in the study area in three replicates, based on therandomized complete block design (RCB). In each tillage system, 10 soil samples of about 0.5 kg (wet) weight for each sample (totally 30 soil samples) were taken from two soil depths (0-25 and 25-40 cm) using a 4 cm diameter Edelman auger. Some physicochemical properties of soil such as total soil organic matter, soil texture, bulk density, and mean weight diameter were measured. Tillage systems did not have any positive effects on soil organic matter (SOM) at two different soil depths (0-25 and 25-40 cm). However, the results showed that no-till system significantly (P>0.05) increased the SOM content of the total measured soil layer (0-40 cm) in comparison with other tillage systems. There is no significant difference in the effects of soil tillage managements onsoil bulk density. Moreover, all these three soil tillage systems caused nonsignificant change on soil aggregate stability against erosive factors.