Evaluating 4R phosphorus stewardship for stress resilient sunflower production

Abstract

The 4R nutrient stewardship framework (right source, right rate, right time, and right place) is a well-established strategy for promoting low-input, stress-resilient, and sustainable crop production. A field experiment was conducted to evaluate sunflower response to 4R-based phosphorus (P) management, using a randomized complete block split-split plot design. The treatments included two P application methods (banding near seed rows and broadcasting), two P sources [monoammonium phosphate (MAP) and diammonium phosphate (DAP)], and five P rates (0, 30, 60, 90, and 120 Kg P₂O₅ ha⁻¹), applied at sowing. Banding was found to be the superior application method, while MAP significantly enhanced plant height, head diameter, 1000-achene weight, and P concentrations in leaves and grains compared to DAP. The highest values for growth, yield, and oil content were recorded at 120 Kg P₂O₅ ha⁻¹. The interaction between P source and method was non-significant; however, significant interactions were observed between application method and P rate for achene yield, stalk and leaf P concentrations, and oil content. Moreover, the interaction between P source and rate significantly influenced these parameters. A three-way interaction (source × method × rate) was significant for stalk P concentration and oil content. Overall, the best performance was achieved with 120 Kg P₂O₅ ha⁻¹ of MAP applied via banding near seed rows at sowing. Nevertheless, banded applications of 30 and 90 Kg P₂O₅ ha⁻¹ were found suitable for low- and high-input economic sunflower production, respectively. These findings align with 4R principles and promote P-efficient, resilient, and profitable sunflower cultivation.