Spatial and In-Depth Distribution of Soil Salinity and Heavy Metals (Pb, Zn, Cd, Ni, Cu) in Arable Irrigated Soils in Southern Kazakhstan

Most irrigated lands in the Republic of Kazakhstan are in its southern part, in the large deltas and ancient alluvial plains in the basins of the rivers Syr Darya and Ili. The combination of climatic features and anthropogenic pressures leads to increased salinity and contamination of cultivated soils in this region, resulting in a qualitative and quantitative decline in crop production. The study’s primary goal was to assess soil secondary salinity and selected heavy metals (Pb, Zn, Cd, Ni and Cu) contamination in irrigated arable soils. To identify the potential source of soil pollution, we compared the concentration of salt and heavy metals (both total and mobile forms) in different soil types in three depths of soil profiles obtained from irrigated cultivated and non-cultivated (abounded) territory in the Shauldara massif in the southern part of Kazakhstan. All studied soils are prone to secondary salinization with either a medium or high content of sum of salts with domination by Na+ among cations and by SO42− among anions. The soil contamination with heavy metals was low, and, in most cases, except for cadmium, it was below the limits developed for arable soils in most countries. Soil contamination with cadmium results from contamination of the water used for irrigation of farmland

Spatial and In-Depth Distribution of Soil Salinity and Heavy Metals (Pb, Zn, Cd, Ni, Cu) in Arable Irrigated Soils in Southern Kazakhstan

Most irrigated lands in the Republic of Kazakhstan are in its southern part, in the large deltas and ancient alluvial plains in the basins of the rivers Syr Darya and Ili. The combination of climatic features and anthropogenic pressures leads to increased salinity and contamination of cultivated soils in this region, resulting in a qualitative and quantitative decline in crop production. The study’s primary goal was to assess soil secondary salinity and selected heavy metals (Pb, Zn, Cd, Ni and Cu) contamination in irrigated arable soils. To identify the potential source of soil pollution, we compared the concentration of salt and heavy metals (both total and mobile forms) in different soil types in three depths of soil profiles obtained from irrigated cultivated and non-cultivated (abounded) territory in the Shauldara massif in the southern part of Kazakhstan. All studied soils are prone to secondary salinization with either a medium or high content of sum of salts with domination by Na+ among cations and by SO42− among anions. The soil contamination with heavy metals was low, and, in most cases, except for cadmium, it was below the limits developed for arable soils in most countries. Soil contamination with cadmium results from contamination of the water used for irrigation of farmland

A Study of the Processes of Desertification at the Modern Delta of the Ili River with the Application of Remote Sensing Data

The water regime is the main factor contributing to the formation of landscapes in the river deltas of arid zones, any fluctuations in which lead to a change in the integral hydromorphic landscape. After the construction of the Kapshagai reservoir, the anthropogenic load on the ecosystem of the Ili River delta increased, as a result of which degradation processes, such as drying out and salinization, intensified. In the short term, this phenomenon may lead to the desertification of about 1 million ha of land in the modern river delta. In this regard, the main goal of this study is to look at the processes of desertification in the modern delta of the Ili River, using remote sensing data, which allows for quick identification of the long-term dynamics of degradation processes. For this, the authors used satellite data from Landsat 1–5 MSSS and Landsat 8OLI satellites for 1979 and 2019 and soil analysis data obtained through the ground (field) surveys. Using regression analysis of space and soil data, predictors for interpreting space images were identified and maps of landscape drying and soil salinization were compiled, reflecting the changes that have occurred over the past 40 years. As a result, it was found that in 2019, compared to 1979, the area of landscapes covered with vegetation had decreased by 12% and there was a transformation of hydromorphic landscapes into salt marshes and solonetzes. Over the past 40 years, the volume of non-saline soils has decreased by 41.3% and the volume of saline soils has increased to varying degrees. That is, at present, on the territory of the modern delta, a difficult land improvement situation has developed associated with the cessation of spring and summer floods due to the intensive water use at the Chinese and Kazakh sides

Mapping of Cornfield Soil Salinity in Arid and Semi-Arid Regions

Soil salinization and their annual increase in volume is not only one of the main problems of arid and subarid regions, but it is becoming global. Studying the problem of salinization and its spatial distribution using operational remote sensing methods is very important for Kazakhstan, where almost half of the agricultural land is exposed to salinization, but it is at the initial stage of development in the use of space technologies of research. The main goal of this study is to conduct a field study of soil salinity in corn fields, one of the most common crops in the arid region of the country, located in the Shaulder irrigated massif, using space-based methods, and to create algorithms for compiling a salinity map based on remote sensing data. For this purpose, firstly, using Sentinel-2 images, the method of separating corn from other dominant crops in the region by creating NDVI dynamics covering all phases of growth of agricultural crops was shown. Then, a regression analysis was performed on soil and vegetation indices calculated using satellite images and data on soil salinity obtained through field studies. As a result of the analysis, the main predictor of deciphering salinized soils was determined. By dividing the predictive image into quartiles, contours of salinized soils were determined and a soil salinity map was created. With the help of the soil salinity map, it was found that, non-saline soils – 2912.2 ha; slightly saline soils – 3288.4 ha, moderately saline soils – 2615.2 ha, and strongly saline soils – 1284.3 ha in the study area