This work studied the use of polylactic acid added with calcium oxide (CaO) and 3-Iodo-2-propynly butyl carbamate (IPBC) for agricultural applications. CaO content of 30 pph was fixed, while IPBC contents were varied at 0, 2.5, 5.0, 7.5 and 10.0 ppm in the polymer matrix. All ingredients were mixed by the extrusion process for receiving the PLA, PLA/CaO, and PLA/CaO/IPBC granules. The pH value, antifungal activities of Phytophthora parasitica, tomato growth, and disposal degradation were also investigated. The experimental results indicated that the acidic condition of the PLA granules increased with increasing IPBC contents but was compromised by CaO. An IPBC was an effective antifungal agent. It was also promoted and activated by CaO. Growth of P. parasitica can be inhibited by CaO synergized IPBC for the PLA/CaO granules with four different IPBC contents and the PLA/CaO granules with the four different IPBC contents were an effective antifungal agent. A PLA/CaO granule with an IPBC content of 2.5 ppm can be developed to compete with an unused condition. A PLA/CaO granule with an IPBC content of 10 ppm was recommended for agricultural applications. A PLA/CaO/IPBC 10 acted as an effective antifungal agent and compostable for soil bioremediatory before planting. Over the 45-day experimental period, the maximum percentage of weight loss of a PLA/CaO granule with an IPBC content of 10 ppm was influenced by moisture and initial PLA loading. A PLA/CaO granule with an IPBC content of 10 ppm (47.2%) had a faster degradation rate than a PLA/CaO granule (45.3%) and a neat PLA granule (15.0%).