Пространственно-временной анализ влажности почв сельскохозяйственных полей

Abstract

Studies of the spatial-temporal variability of the field soil moisture content of three experimental fields located in the Perm district of the Perm region were carried out. The experimental conditions were pure fallow. The purpose of the work is to perform a spatio-temporal analysis of soil moisture in experimental fields using mathematical-cartographic and remote sensing methods. Field soil moisture was measured by points placed taking into account the heterogeneity of the soil cover and topography conditions. Based on the measurements performed, maps of field soil moisture were created using the “Ordinary Kriging” geostatistical method, using the Geostatistical Analyst module of the ArcGIS 10.1 program. The assessment of the influence of the relief on the moisture was performed using the SRTM global digital elevation model. Indicators calculated were topographic humidity index and closed depressions. Based on the obtained geostatistical layers, the relationship between humidity and Sentinel 2 satellite data was established through the spectral index NDVI. For the initial and final dates of measurements, correlation coefficients 0.8 and 0.9 were obtained. The nature of dependence turned out to be changeable over time. At the beginning of the growing season, the relationship is inverse, which confirms the indicator role of NDVI in moist areas, but starting from the third decade of May, the relationship becomes positive. This is due to the fact that the treatment of soils is not done every day, and seedlings appear earlier in the areas with the greatest moisture. Therefore, during the growing season, the field moisture content through the NDVI is indirectly identified by the value of the plant biomass. For individual measurement dates, a close correlation was established between NDVI raster maps and field humidity (r = 0.86). The resulting dependence can be used to predict soil moisture in similar areas. The results of the research will be used for differentiated sowing of seeds, taking into account different moisture conditions within the experimental fields.