Seasonal dynamics of nutrients in leached chernozem under phosphate fertilizer application in sunflower crops in the conditions of the Stavropol Upland

Abstract

Introduction. In the North Caucasus region of Russia, leached chernozem soil is the second most common type after typical Chernozem. This soil is characterized by the absence of carbonates and a higher utilization coefficient of phosphorus from fertilizers compared to their calcareous counterparts. However, the efficiency of various forms of phosphorus fertilizers on these soils, especially when cultivating sunflower, remains insufficiently studied.
Aim. To study the influence of phosphorus-containing fertilizers on the seasonal dynamics of nutrient elements in leached chernozem under sunflower crops.
Materials and methods. The research was conducted at the experimental station of the Stavropol State Agrarian University, located on the Stavropol Upland in southern Russia. Sunflower was cultivated on a medium-thick, low-humus, heavy-loamy leached chernozem on loess-like loam. Phosphorus-containing fertilizers were applied at a rate of 52 kg/ha in terms of active substance (P2O5), using the following physical rates: ammonium phosphate (amophos) – 100 kg/ha; diammonium phosphate (diammophos) - 110 kg/ha; liquid complex fertilizers (LCF) – 140 kg/ha; and monoammonium phosphate (MAP) – 85 kg/ha. Fertilizers were applied using three methods: during primary tillage, at sowing, and in a combined manner (50% of the dose during primary tillage and 50% at sowing). Soil samples were collected from the rhizosphere zone (0–20 cm).
Results. It was found that the application of ammophos, diammophos, LCF, and monoammonium phosphate increased the content of nitrate nitrogen and available phosphorus to a greater extent when fertilizers were applied at sowing. During the seedling stage, this resulted in a transition of the available phosphorus status of soil from medium to high. During the growing season, a decrease or absence of differences between the control and the experimental treatments in the studied parameters was observed by the stages of sunflower seedlings and full maturity. The application of fertilizers did not affect the content of exchangeable potassium and available sulfur.
Conclusion. This study demonstrates that applying phosphorus fertilizers at sowing, notably monoammonium phosphate, effectively increases soil available phosphorus for sunflower production in the North Caucasus region.

To cite: Tskhovrebov V.S., Vovk A.M. Seasonal dynamics of nutrients in leached chernozem under phosphate fertilizer application in sunflower crops in the conditions of the Stavropol Upland. Agrarian Bulletin of the North Caucasus. 2025;15(4):47-56. https://doi.org/10.31279/2949-4796-2025-15-4-47-56