Investigation of physicochemical characteristics of soil in badland areas formation

Introduction
Characteristics of Badlands are the lack of vegetation, steep slopes and dense drainage network which are known as important sources of erosion and sediment production in the world. Heavy rains, scattered vegetation, low soil permeability, erodible materials, and steep slopes and slopes provide the conditions for badland faces. Badland erosion is affected by several soil properties, including surface soil depth, soil organic carbon content, organic matter status, soil texture and structure, available water holding capacity, and water transfer characteristics that determine soil quality. Cited. The extent of the influence of different physical and chemical factors of soil in the formation and spread of pustular erosion varies from point to point.
 
Materials and Methods
This study aimed to identify the most important factors of physical and chemical properties of soil and environmental factors and soil depth in the spread of badland erosion in Zanuzchay watershed. In this research, factors such as percentage of sand, silt and clay, PH, EC, SAR, organic matter, gypsum and soil lime in different altitude classes and the east-west direction and in three depths of 0-5, 5-30 and -30 60 Badland erosion faces were investigated. To investigate the effect of soil properties in different directions, altitudes and depths on the formation and development of badland in the study area, a systematic-random plan in the form of a factorial plan with two land use factors and altitudes, through analysis of variance and mean comparison was done by Duncan method. The normality of the data was assessed by the Kolmogorov-Smirnov normality test. Gypsum and SAR variables that had an abnormal state were normalized using root and logarithm of numbers, respectively, and parametric statistical tests were performed on them. Analysis of variance and Duncan's method were used to determine the effect of soil factors on Badland face formation.
Results and Discussion
The results obtained from unpaired t-test and Leven to compare the mean differences of some physical and chemical properties of Badland soils in comparison with control soils showed that the variables pH, SAR, gypsum, clay percentage, silt percentage, and organic matter they are significant at the level of (0.01). According to the investigation of the relationship between the physical and chemical properties of the soil and the formation of the erosion of badlands, it has been determined that the formation of badlands has a direct relationship with the percentage of clay, pH, EC, organic matter and SAR and has an inverse relationship with the amount of lime and gypsum. The results show that with the increase in salinity, the conditions for the establishment of plants decrease, which plays a significant role in reducing the speed of raindrops and their penetration into the ground. The results showed that the chemical factors of the soil largely determine the erosion and formation of badlands. In such a way that with the increase of pH and EC, the tunnel erosion increases and with the increase of lime and gypsum, the amount of sediment formation decreases. The increase of fine clay particles increases the stickiness of marl soil and with the increase of resistance against water action, surface erosion prevails. The increase in soil salinity and sodium absorption ratio causes the creation of fine granular structures in the soil, which disintegrate as soon as moisture reaches them. High amounts of sodium reduce the water conductivity of the soil through the phenomena of swelling and dispersion of clay minerals. The stability and resistance of grain soil decreases with the increase of sodium absorption ratio and as a result, soil erosion is intensified. Organic matter has a vital role on the chemical, physical and biological properties of soil, the change in the amount of organic matter due to its effect on biological activities, cation exchange, acidity and the amount of nutrients is one of the most important indicators of chemical and biological quality. It shows that organic matter plays an important role in the formation of soil grains and improves soil structure. The results obtained from Duncan's test show the difference between the means in different classes and directions and at depths of (0-5), (5-30), and less than 30 cm in both areas of Badland, and The control is at a significant level of 0.05. The results also showed that the average percentage of clay and sand at different heights have a significant difference at the level of 0.05.
 
Conclusion
Considering the relationship between physical and chemical properties of soil with the formation of Badland erosive faces, many studies show that the formation of Badland has a direct relationship with the percentage of clay, pH, EC, organic matter, and SAR and is inversely related with the amount of lime and gypsum.