Efficiency of mineral fertilizers application in winter wheat cultivation under low availability of mobile phosphorus in the soil in the Rostov region

Field experiments were conducted in the Azov district of the Rostov region in 2022–2024. The winter wheat variety Grom was grown. The predecessor was sunflower. Before the field experiments, the soil of the experimental plots was characterized by an extremely low content of mobile phosphorus in the 0–40 cm layer, which corresponds to the Machigin classification (0–10 mg/kg of soil). Complex mineral fertilizers were applied during sowing and by scattering, ammonium nitrate fertilization was carried out on frozen soil and in the spring tillering stage. The following mineral fertilizers were applied in the field experiments: nitroammophoska N:P:K (16:16:16 kg of an active ingredient), ammonium nitrate (34.4% of nitrogen), ammophos N:P (12:52% of an active ingredient), sulfoammophos N:P:S (20:20:14 kg of an active ingredient). The yield in the control variant was, on average, 1.80 t/ha for 2023–2024. The application of ammonium nitrate at a dose of N103.2 contributed to the greatest effect compared to the pre-sowing application of sulfoammophos at a dose of N30P30S21. The increase in yield compared to the control variant was 2.33–2.34 t/ha, i.e. 129.2–130.0%.