The Effect of Changing Land Use of Almond Orchards in Saman Plain of Chaharmahal and Bakhtiari Province to Agricultural Lands on Some Physical and Chemical Indicators of Soil Quality

In recent years, some farmers in the plains of Saman in the province of Chaharmahal and Bakhtiari have changed the use of almond orchards in this area to agricultural land and pastures in order to provide food and fodder. Since these activities are mostly carried out without sufficient knowledge of the soil environment, there can be a serious threat to reduce soil quality. Therefore, studies on the effect of different managements on different soil characteristics and in the direction of a sustainable soil resource are very important. In this research, the effect of land use change in these areas on some physical and chemical indicators of soil quality was investigated.

In order to investigate the effect of land use change on some physical and chemical indicators of the soil quality of three land use systems comprising a permanent almond orchard, permanent pasture and almond orchard converted to land were selected in the plain of Saman. 15 samples of soil (45 samples in total) were taken from 0 to 30 cm in the form of networks (30 x 30 meters) in each of the three land use systems considered. Some physical and chemical parameters of studied soil samples measured by standard methods.After collecting and saving data in Excel, a one-side analysis of variance (ANOVA) was performed on using the SPSS18 software and the comparison of the means was also carried out on the basis of the LSD test at a probability level of 1%.

The results of analysis of variance data showed that changing land use (changing of almond orchards to agricultural land) had significant effect on the indeces examined physical and chemical of at 0.01 level. The Land use change did not change the surface soil texture of the study areas. The soil texture of all three-study system was almost the same (clay loam inclined to sandy clay loam). According to the findings of the mean comparison, when almond orchards were converted to agricultural land, there was a significant reduction in total porosity, mean weighted diameter of soil aggregates (MWD), base infiltration rate, and soil organic carbon by 12%, 56%, 50%, and 54%, respectively. Conversely, there was a notable increase of 10%, 5%, 44%, and 18% in bulk density, pH, electrical conductivity, and soil lime percentage at a significance level of 0.01 (pr<0.01).In this study, substituting improved pasture plants with land grazed pasture significantly augmented the average of soil organic carbon, total porosity, solidity of soil aggregates (MWD) and base infiltration rate by 48%, 14%, 69%, and 40%, respectively, as compared to agricultural land at a significance level of 0.01 (pr<0.01). However, no significant difference was observed at a significance level of 0.01 (pr>0.01) between almond orchard and pasture land concerning the evaluated indicators.

Overall, the parameters analyzed indicate that organic carbon, mean weighted diameter of soil aggregates (MWD), and bulk density are reliable indicators of soil quality in the study area. The average values of these indicators provide an optimal alternative for management and tillage practices in various land uses. Moreover, due to the delicate and vulnerable ecosystems of Saman Plain, it is recommended to avoid converting garden lands (such as almond orchards) into agricultural lands within the study area. This approach will help prevent soil erosion in one of the most sensitive areas of the country.