Straw returning is an environmentally friendly method to improve soil health and agricultural productivity by reusing organic waste products. However, fields are often also treated with inorganic fertilizers, and the effect of the interaction between phosphate fertilizer application and straw return on crop yield remains unclear. Therefore, a full-factorial, two-year field experiment was conducted on sweet corn (NARC-16 in late 2021 and Kashmeri-19 in early 2022) to explore how crop yield may be optimized by combining straw return with efficient phosphate fertilization. The experiment involved the application of DAP, SSP, and NP (three different types of phosphates) and the application of crop waste byproducts, namely the residual stover left after sorghum and maize harvesting. We compared control fields with no crop waste or phosphate addition (CR0 and PS0) to experimental plots treated with various phosphates and straw return. Growth parameters such as days to emergence, tasseling, silking and maturity, emergence rate (emergence m−2), height of plant, number of leaves, leaf area per plant, and yield were evaluated, and the influence of the treatment on the economic value of crops was estimated. Phosphorus and straw return were applied at rates of 90 kg per hectare and 5 tons per hectare, respectively. The best P-crop straw combination treatment involved DAP (90 kg ha−1) with the incorporation of 5 tons’ ha−1 of maize straw, which resulted in delayed tasseling (50 days), early silking (68 days), taller plants (178 cm), improved thousand-grain weight (233 g), maximum biological yield (11,349 kg ha−1) and grain yield (3760 kg ha−1). The application of DAP with maize straw return resulted in the highest plant height, biological yield, and grain yield of sweet corn during the second year of the experiment, despite the first year’s yield being influenced by a natural disaster. This combined management strategy (using either DAP or crop residuals) was found to have a more a favorable cost–benefit ratio (BCR) efficiency. In conclusion, increasing the use of crop residuals can help reduce the expensive application of synthetic mineral fertilizers like SSP and NP, while significantly increasing sweet corn production and improving profit margins. Considering the importance of environmental friendliness and sustainable agriculture, the combined use of DAP and straw return is considered a viable method.
