Effects of Soil Compaction on Soil Carbon and Nitrogen Sequestration and Some Physico-Chemical Features (Case Study: NorthofAqQala)

Soil compaction has become a widespread problem in the world and it is considered as one of the main factors affecting land degradation in arid and semi-arid agricultural land. The aim of this study was to investigate the effects of soil compaction on soil carbon and nitrogen sequestration, physical (aggregate stability, saturated soil moisture content, bulk density, and porosity) and chemical (EC, pH, organic carbon and nitrogen) features. The treatments were applied in the form of the completely randomized block design with four independent variables and three replicates. The study treatments included: control treatment (no artificial compaction), T2 (2 times passing heavy tractor), T3 (4 times passing heavy tractor) and T4 (6 times passing heavy tractor). Toward this attempt, data was analyzed by means of the SPSS 16.0. Software package. The type of mean comparison method applied is the LSD test (at significant level of 5%). The results showed that different levels of soil compaction caused a significant effect on soil physical and chemical features. Based on the results, 6 times passing heavy tractor significantly reduced soil porosity and aggregate stability (respectively from 0.45% and 5.32 mm in control treatment to 0.255% and 3.88 mm) while this treatment (4) significantly increased soil bulk density as compared to other treatments(from 1.45 g cm-3 in the control to 1.97 g cm-3). Four and six times to-and-fro passing heavy tractor caused a significant reduction in soil carbon and nitrogen sequestration respectively from 3.26 t ha-1 and 149.62 kg ha-1 (in control) to 1.70 ton ha-1 and 48.16 kg ha-1for T3 and T4 treatments, but significantly increased EC in comparison with other treatments (changed from 0.58dS m-1 in control treatment to 0.83dS m-1 in T4). Also, all soil compaction treatments significantly increased soil pH. For example pH increased from 7.93 in control to 8.09 inT4. While soil compaction treatments resulted in significant decrease in organic carbon, total nitrogen and saturated soil moisture values.