Using of NDVI in digital mapping of phosphorus content in soils and assessment of it's availability by plants

It was developed а method of digital mapping of phosphorus content (total, organic, available) in soils using spatially distributed NDVI values calculated from Landsat 8 (30 m resolution). It was carried out comparative analysis of content of phosphorus of soils differing in soil humus content: with high and medium humus content. In medium-humus soils (agrochernozems, agro-dark-grey) compared to high- humus agrochernozems discovered lower contents of total phosphorus in 1.1 times, and organic phosphorus in 1.5–1.7 times. The reverse trend was found for available phosphorus — in all medium- humus soils its content was more in 2 times as compared with high-humus agrochernozems. The provision of plants with phosphorus was sufficient, since its content in the above-ground phytomass of the oat-pea mixture was in the optimal range of 0.23–0.5% for a completely dry mass. According to the visual diagnostics of external signs of phosphorus deficiency in plants was not revealed. It was not found correlation between the content of phosphorus in plants, the reserves of above-ground phytomass of oat-pea mixture and NDVI.