Formation of the root system of oilseed radish under long-term green manuring practices

The optimal selection of plant species for green manuring technologies is impossible without assessing the bioproductivity and morphometry of their root systems, which is an additional and significant factor in the effectiveness of both the growth processes of the green manure crop and its projected impact on the soil profile as a whole. Taking this into account for 11-year period, the bioproductivity of the root system of oilseed radish was assessed by morphological and weight parameters in the soil profile for two sowing dates of green manure: spring and summer. A wide range of methods based on Profile Wall, Monolith Method and Root maps of a profile wall were used to obtain the main functional indicators of the formation and spatial development of the root system. It was determined that oilseed radish from the point of view of formation of morphological characteristics of the root system provided the yield of root biomass in dry matter of 1.19–1.77 t ha-1 in active interaction with the soil profile 40–80 cm deep with the formation of the following components of the root system morphotype in the range of long-term average values for sowing dates: average diameter of the root taproot 5.13–5.67 mm at its taper 0.55–0.66, volume 26.92–39.09 cm3, volume of root spreading zone 36.75–66.39×103 cm3, fractal dimension (D) 0.63–0.73, maximum root depth 47.36–64.41 cm, fraction of total root mass to the soil depth (0–30 cm) 0.77–0.79. The dependence of the formation of indicators of bioproductivity of the root system with a direct nature on the amount of precipitation (determination 47.19–50.20%), water reserves in the soil (27.04–65.61%) and an inverse nature on the average daily temperature (21.44–25.70%), Vysotsky-Ivanov humidification coefficient (57.30–65.45), De Martonne Aridity Index (47.75–51.12) and soil hardness (37.21–59.29%) was determined.