Research Article Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes Latifah Omar, 1 Osumanu Haruna Ahmed, 1,2,3 and Nik Muhamad Ab. Majid 3 1 Department of Crop Science, Faculty of Agriculture and Food Sciences, Universiti Putra Malaysia, Bintulu Sarawak Campus, 97008 Bintulu, Sarawak, Malaysia 2 Agriculture and Environment, Borneo Ecosystem Science Research Centre, Faculty of Agriculture and Food Sciences, Universiti Putra Malaysia, Bintulu Sarawak Campus, 97008 Bintulu, Sarawak, Malaysia 3 Institute of Tropical Forestry and Forest Product (INTROP), Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia Correspondence should be addressed to Osumanu Haruna Ahmed; osman60@hotmail.com Received 18 November 2014; Accepted 27 January 2015 Academic Editor: Ayako Oyane Copyright © 2015 Latifah Omar et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Improper use of urea may cause environmental pollution through NH 3 volatilization and NO 3 − leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH 4 + and NO 3 − release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH 4 + and NO 3 − losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH 4 + and NO 3 − release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO 3 − leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH 4 + retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. ese observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH 4 + and NO 3 − release from urea. 1. Introduction Depending on soil pH, moisture, and application methods, urea undergoes chemical transformation to produce either NH 4 + or NO 3 − [1]. Nitrogen from urea is subject to loss from a number of pathways of which leaching of NO 3 − is one of the most important pathways because NO 3 − is extremely mobile. Leaching of NO 3 − from urea leads to increase in NO 3 − concentrations in surface and ground water [2]. Leaching losses of N occur when soils have more incoming water than they can hold. As water moves through the soil, NO 3 − in the soil solution moves along with the water. Because NH 4 + is positively charged, it is held by the negative sites of soils (e.g., clay and humus); therefore, NH 4 + leaches less in mineral soils which are particularly high in clay [3]. In contrast, NH 4 + leaching is significant in coarse-textured sands and some muck soils [4]. us, agricultural systems research leading to management practices that improve N utilization efficiency and decrease N losses is essential [5]. Nitrogen leaching loss in soils is a risk because if NO 3 − is not absorbed by the plant root system, it is leached below the root zone of plants, thus contaminating groundwater [6]. According to Paramasivam et al. [7], optimization of irrigation and avoidance of fertilization during rainy seasons could minimize leaching loss of N. However, this approach can be difficult to achieve because rapidly growing crops Hindawi Publishing Corporation e Scientific World Journal Volume 2015, Article ID 574201, 12 pages http://dx.doi.org/10.1155/2015/574201