Formulasi dan Pola Kelarutan N Pupuk Urea-Zeolit Lepas Lambat

Abstrak.  Upaya pengendalian pelepasan Urea secara perlahan dapat dilakukan dengan memformulasi pupuk Urea dengan Zeolit dan penyalutan Kitosan sehingga dapat menyediakan hara N secara lambat, dan meningkatkan efisiensi pemupukan , produktivitas tanah dan tanaman . Tujuan penelitian ini adalah memformulasi dan mempelajari kelarutan N dari formula pupuk Urea dan Zeolit yang berukuran submikron dan yang disalut dengan Kitosan. Penelitian dilaksanakan di Laboratorium dengan rancangan percobaan Rancangan Acak Lengkap dengan 3 ulangan. Perlakuan yang dicobakan adalah 1) Kontrol lengkap (tanpa pupuk), 2) Urea prill (pupuk standar), 3) Formula Urea + Zeolit, dan 4) Formula Urea + Zeolit + Kitosan. Pengamatan yang dilakukan yaitu kelarutan N-total, N-NH 4 dan N-NO 3 selama inkubasi 2, 4, 6, 8, 10, dan 12 minggu. Hasil penelitian menunjukkan bahwa formula pupuk Urea + Zeolit dengan perbandingan 3:2 yang disalut Kitosan memberikan kelarutan N-total sebesar 25,43% pada inkubasi 12 minggu dibandingkan Urea prill sebesar 43,43%. Selama inkubasi perlakuan kontrol memberikan kelarutan N-total paling rendah, karena kadar N tanah awal rendah. Formula pupuk Urea + Zeolit yang disalut Kitosan dapat meningkatkan efisiensi pemupukan melalui kelarutan N yang slow release sehingga mampu mengurangi penguapan dan pencucian pupuk Urea. Abstract . The efforts to slow down Urea release can be conducted by formulating of Urea and Zeolit, and followed by chitosan encapsulation. The formulation can release Nitrogen (N), increase the efficiency of fertilization, and increase soil and crop productivity. This research was aimed to formulate and evaluate the solubility of N from Urea and submicron-sized Zeolit followed by coating with chitosan. The experiment was conducted from April to December 2012 at the Laboratory with experimental design of completely randomized design with three replications. The treatments tested were 1) Complete control, 2) Prilled Urea, 3) Formula of Urea + Zeolit, and 4) Formula of Urea + Zeolit + chitosan. Observations included solubilities of total N, NH 4 -N, and NO 3 -N during the incubation of 2, 4, 6, 8, 10, and 12 weeks. The results showed that the formula of Urea + Zeolit fertilizer with the ratio of 3:2, encapsulated with chitosan gave a total N-solubility of 25.43% at 12 weeks incubation, which was significantly lower than that of prilled Urea of 43.43%. During the incubation, the control treatment gave the lowest total N-solubility, because of the low initial N soil content. The formula of Urea + Zeolit coated with chitosan can increase fertilizer efficiency through slow release N solubility so as to reduce volatilization and leaching of Urea fertilizer.