LAUSR

In this work, barley seed coating with urease and phosphatase, free and immobilized in humic acids, was studied as a tool to enhance the use efficiency of N and P by plants. The seeds were encapsulated in gels of Ca-alginate by a method that allows gelation of the polymer, containing enzymes, from the surface of seeds outward. The coating process did not affect seed germination. A pot experiment with the coated seeds was carried out. The seed coating with free enzymes increased soil ammonium-N (NH4 +-N) and inorganic P up to 39 and 54 %, respectively, and up to 62 and 64 %, with the immobilized enzymes, in comparison with control pots. Seed coating improved N (47-137 %) and P (29-61 %) uptake by plants. Moreover, a synergistic response in N and P uptake with both urease and phosphatase was observed. It can be concluded that the seed coating with urease and phosphatase exerted a positive effect enhancing the use of N and P by plants, which could lead to the development of natural fertilizers, minimizing the application of chemical fertilizers.