تاثير كاربرد بيوچار سرشاخه‌هاي درخت سيب بر شاخص‌هاي كيفيت خاك و عملكرد و ماده موثره دوگونه آويشن در شرايط ديم و آبي

Thymus sp. is one of the widely known spicy aromatic an‎d medicinal plants widely used in medicine, cooking an‎d perfumery. Biochar is an amendment to improve soil quality attributes. However, the interactive effect of Thymus cultivation an‎d biochar application rate on soil quality indicators an‎d plant growth attributes in the field conditions is not well documented. This study aimed to investigate the effect of biochar of apple tree branches (BAR, 0, 30 an‎d 60 Mg ha-1), two Thymus species (TS, T. daenensis an‎d T. migricus), an‎d soil sampling zone (SSZ, rhizosphere an‎d bulk soil) on quality indicators of a silty clay loam soil, an‎d yield, essence an‎d their components of Thymus in rainfed an‎d irrigated conditions. The study continued for two years to explore the time-dependent effects of treatments as well. The experiment was conducted in a ran‎domized complete block design with a factorial arrangement of the 12 treatments (i.e., 3 levels of BAR × 2 levels of TS × 2 levels of SSZ) with three replicates. After plant harvest, the soil aggregate stability was characterized by high energy moisture characteristic (HEMC) an‎d percent of water-stable aggregates (WSA), an‎d the soil water repellency was measured by the sorptivity method. Water infiltration into the soil was measured by a tension/disk infiltrometer in the field. The infiltration data were modeled by the analytical method proposed by Wooding (1968) to optimize soil hydraulic parameters of saturated hydraulic conductivity (Ks) an‎d macroscopic capillary length (λc). Biochar affected soil structural stability indices in both rhizosphere of the two Thymus species an‎d bulk soil. The results showed that biochar application enhanced the soil organic carbon (SOC) an‎d consequently increased the HEMC stability ratio. Water holding capacity in the biochar treatments was higher in all matric suctions, therefore, greater HEMC aggregate-structure stability indices were measured in the biochar-amended soils. The rhizosphere soil had significantly greater mean of organic carbon storage, stability ratio an‎d water repellency index compared to those in the bulk soil. The rhizosphere of T. migricus (with greater root development in the upper layers) had significantly greater WSA compared to that of T. daenensis. However, there was no significant difference between the two plant species for SOC in the rhizosphere. This finding implies that quality (not quantity) an‎d fractions of organic matter might be different in the rhizosphere of the plant species. Water repellency could partly explain the structural stability differences in the rhizosphere of T. daenensis an‎d T. migricus species. Analysis of the hydraulic properties data related to soil water infiltration data showed that both Ks an‎d λc were significantly affected by the TS, BAR, an‎d the time factor in both rainfed an‎d irrigated conditions. The BAR of 30 Mg ha-1 resulted in greater soil infiltrability due to biochar’s positive effects on soil structure an‎d pore size distribution. Higher BAR (i.e., 60 Mg ha-1) was not as effective as the lower BAR on soil infiltrability; it seems that soil macropores have been filled by the hydro‎phobic particles of biochar at high rate. The biochar’s effects on water infiltration were more evident in the second year. The results showed that under both rainfed (drought stress) an‎d irrigated (normal) conditions, the application of biochar had significant effects on the phytochemical parameters. The highest shoot yield an‎d essential oil yield were recorded as 33.96 an‎d 0.37 g m-2, respectively, in the combination of BAR = 60 Mg ha-1 an‎d irrigated conditions. For T. daenensis, the essential oil content exhibited an increase under water-limited (rainfed) condition when compared to irrigated condition. The most substantial increase in total phenolic content was observed when BAR of 60 Mg ha-1 was applied under the drought stress condition.

محمدرضا مصدقي

مهدي قيصري , مهدي رحيم ملك

محمدعلي حاج عباسي جورتاني , محمد شايان نژاد , شجاع قرباني دشتكي