<p>Fertilizers are a class of agrochemicals essential to improve the nutritional soil quality and crop production. One challenge in the fertilizer application is controlling the losses from leaching and aerial dispersion, being an economic and environmental issue. A promisor alternative is the use of fertilizer systems that guarantee adequate packaging and posterior release when in contact with the target desirable. In this sense, biodegradable starch sachets are an interesting system for packaging and fertilizer delivery. The great advantage is the nutritional composition adequation inside the sachets to attend to the demands, not affecting the biopolymer matrix processing. Thus, the present work aimed to develop a multifunctional system based on a starch sachet reinforced with copper-faujasite zeolite (Cu-FAU) for potassium packaging. Besides, the innovation consists in evaluating the availability of the copper and nitrogen (urea) present in the polymeric matrix, as secondary nutrition sources. The starch matrix was plasticized in the presence of urea and citric acid, following the sachet molding applying a pressing. The results indicate that the addition of citric acid 3% (w w⁻¹) increased the water vapor barrier and the tensile strength. Urea and Cu²⁺ ions release occurred partially, once the sachets were preserved in an aqueous medium for 30 days. Concerning chloride potassium (soluble salt), the higher hydrophilicity of sachets favored a quick opening of the packaging, dissolving it when in contact with the external environment. Furthermore, the Cu-FAU showed fungistatic activity against <i>Alternaria alternata</i> fungus. This result indicates that the copper could control the degradability of the sachets until the soil application. Thus, the starch sachets demonstrated an easy way to package the potassium and facilitate the manipulation during the storage, preserving the higher solubility properties for a posterior release.</p>