Effectiveness of Various Forms of Neutralized Phosphogypsum as a Multicomponent Fertilizer for Rice Crops

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The effectiveness of various forms of neutralized phosphogypsum (bulky, granular, multicomponent organomineral fertilizer (MOMF)) was evaluated when used as a multicomponent fertilizer for rice crops. The study was carried out on meadow-chernozem rich low-humus heavy-loamy soil of irrigation rice systems of the Krasnodar Territory. The rate of application of phosphogypsum was equivalent in terms of the content of P₂O₅ entering the soil with mineral fertilizer (N120P60K40). We studied 2 terms of its introduction: in autumn and early spring. There were no significant differences in the phosphorus content in the soil when applying ammophos and phosphogypsum in various physical forms and at different seasons (autumn, spring). When applying phosphogypsum in autumn, the soil contained more mobile sulfur than in the control: in spring before rice sowing – by 76.0–78.0, in the tillering phase – by 72.2–128, earing – by 71.9–131, full ripeness – by 70.0–133%, when applied in spring – by 83.7–87.8, 85.0–113, 88.6–117, 87.1–123%, accordingly. Most of the sulfur entered the soil with bulky phosphogypsum, less with granular. Phosphogypsum affected the intake of nitrogen, phosphorus, potassium and sulfur by rice plants. When applied in autumn, the most favorable conditions for the absorption of these elements by plants were formed when using bulky phosphogypsum, when applied in spring – granular and MOMF. The yield of rice when applying phosphorus with mineral fertilizer (ammophos) and phosphogypsum (bulky, granular, MOMF) did not differ significantly, i.e. neutralized phosphogypsum was equal in efficiency to ammophos.