Photosynthetic and Carbon Sequestering Ability of Safflower Leucea and Accumulation of Organic Carbon in Sod-Podzolic Soil

According to the content of photosynthesis pigments, the most active period of photosynthetically active radiation absorption by the leaves of Leucea safflower during the growing season was revealed. From the moment of full regrowth to flowering, the amount of chlorophylls a and b in the leaves was 6.2–8.5 mg/g of dry weight, carotene – 3–4 times less. During photosynthesis, the carbon content in the leaves of Leucea safflower practically did not change and amounted to 39.5–42.5%. The mass fraction of the main product of photosynthesis, sugars, increased from the regrowth phase to seed formation from 4.0 to 11.8%. During the period of active growth, the nitrogen content in the leaves of the leucea was 1.3–1.6, phosphorus – 1.1–1.6, potassium – 4.4–5.1%. After harvesting the safflower leucea of the 14th year of life, a high amount of сrop and root residues (CRR) was determined in the sod-podzolic soil – 13.7–17.3 t/ha. The amount of carbon absorbed during photosynthesis was 6.8–11.5 t C/ha (24.3–41.3 t CO₂/ha), depending on the experiment variant, for natural phytocenosis this indicator was equal to 2.4 t C/ha (or 8.6 t CO₂/ha) during the growing season. The organic carbon content under the safflower leucea of the 14th year of life in the 0–20 cm soil layer increased relative to the initial level by 3.6% in the version without fertilizers, by 15.1% in the N60P60K60 variant, and in the 20–40 cm layer by 8.8–42.6%, respectively. Relative to the virgin analogue, the carbon content in the 0–20 cm layer was 15.2–28.0 higher, in the 20–40 cm layer – 25.0–64.4%, depending on the experiment variant, which indicated the deposition of carbon in the form of humic substances due to its storage in deeper soil layers.