Assessment of the spatial and temporal heterogeneity of available phosphorus content in arable soil on the scale of one field (using the example of the Republic of Tatarstan, Russia)

Based on the digital soil mapping approach using Landsat 5/Landsat 8 satellite data and morphometric terrain attributes, the spatiotemporal heterogeneity of available phosphorus content in agricultural soils of the territory of scientifically based agriculture for the period from 1987 to 2021 was assessed. It was found that available phosphorus at very high content has high and close to very high spatial variability (coefficient of variation = 25-32%). It was revealed that over the past 34 years, the content of available phosphorus in arable soils has changed significantly, and the spatial heterogeneity of available phosphorus content has increased over time. It was determined that the maximum average available phosphorus content was recorded in 2011 (494 mg/kg), by 2021 the available phosphorus content is decreasing to the level of 1987 and averages 301 mg/kg. It is analyzed that random forest models describe 64-68% of the spatial heterogeneity of the available phosphorus content depending on the year. It is determined that the predicted values of the available phosphorus content approach the observed values, their confidence intervals overlap It has been established that both remote sensing data and morphometric terrain attributes can contribute to the prediction of spatial heterogeneity of available phosphorus content in different years.