Using multispectral images to determine the salinity of soils in Ingulets irrigation system in the justification of management measures for chemical reclamation

Abstract

The publication presents the use of data from multispectral space images to substantiate management measures for chemical reclamation of saline soils of the Ukraine irrigation system. The study is to develop a method of using satellite data to remotely determine the salinity of soils to support the management measures on the chemical soil improvement by example some fields of Ingulets irrigation system. Landsat 8 OLI images were used to obtain NDVI, soil salinity assessment indices, namely VSSI, Salinity index and normalized soil salinity index (NDSI). The verification data on the spatial distribution of salinity are taken from the report on soil-salt survey of the Ingulets irrigated massif. Work with satellite images and calculation of indices was performed using ERDAS IMAGINE 2015. Quantitative analysis of pixels, their visualization using the color spectrum was carried out in ArcMap 10.8. Validation for the conditions of Ukraine on the southern chernozems of the salt indices (VSSI, NDSI, SI) showed the best suitability of NDSI. Using the calculated ranges of index that characterize the gradation of salinity, their area percentage has been determined for each experimental field of the pilot object. The salinity areas according to each gradation were obtained on the basis of NDSI. Quantitative values of the management measure, the dose of chemical ameliorants, differentially for each of the fields are obtained using calculation methods using the author’s information technology. The total amount of phosphogypsum for chemical reclamation is recommended. The results of the study show that Landsat 8 OLI images show a high potential for spatio-temporal monitoring of salinity of the upper soil layers. This study will be useful for planning agricultural activities by mapping the salinity of the soil with the calculation of doses of chemical ameliorants to reduce economic losses in climate change. The proposed norms of gypsum application can serve as a guide for the agricultural producer when making a decision on chemical reclamation of agricultural lands. Based on a combination of satellite monitoring data and calculations of chemical reclamation doses according to the author’s online calculator, the farmer will be able to assess the feasibility and economic efficiency of chemical land reclamation measures. An additional practical value of the method of remote determination of boundaries and area of salinity is the ability to plan the selection of soil samples from certain points of the field, optimizing the number of soil samples for their chemical analysis in the laboratory. Our proposed method, which estimates soil salinity using satellite images and suggests doses of chemical ameliorants using information technology, can be potentially useful as a rapid approach to detecting soil salinity in other regions of Ukraine and the world at low cost and high accuracy