Controlled Release Urea Improved Nitrogen Use Efficiency, Activities of Leaf Enzymes, and Rice Yield

Abstract

The effects of a controlled release urea (CRU) on concentration of N in root zones, activities of N metabolism enzymes in leaves, and N use efficiency of rice (Oryza sativa L.) grown on a silt loam soil in lysimeters were investigated. The entire amount (100–300 kg N ha−1) of the CRU was incorporated into a plug for growing the rice seedlings while the regular urea was split into three applications (the standard practice). Results indicated that the N release of CRU closely matched the N requirements of the rice, and the commingling of the CRU with the rice seeds increased N concentration within the root zone and enhanced the activities of glutamine synthetase (GS), glutamine 2‐oxoglutarate amidotransferase (GOGAT) and nitrate reductase (NR) in leaves. At the same N rate, the apparent N use efficiency of the CRU applied at 300 kg N ha−1 was 27.6 and 22.9% higher than that of conventional urea treatment in 2007 and 2008, respectively. Although the CRU at 200 kg N ha−1 supplied one‐third less N than the urea at 300 kg N ha−1, the CRU produced 3 to 5.9% more grain than the urea. Placing the CRU with rice seeds without additional fertilizer application during the entire growing season significantly increased N availability in soils and improved rice growth and led to use of less N fertilizers for greater rice grain yield.

Nitrogen loss by volatilization of nitrogen fertilizers applied to coffee orchard

“…In the presence of water, the resin membrane becomes permeable by diffusion, and the N release begins inside the granule. The solution formed at the beginning of the dissolution permeates gradually through the coat, contrary to the water flow, and releases N to the soil by diffusion (Du et al, 2006;Du et al, 2008;Trenkel, 2010;Ogle;Sims, 2012;Yang, 2012).…”

“…Therefore, the urea + resin is more advantageous when it is applied in one dose at the beginning of the coffee season than when it used in the three split applications that are usually applied in Brazil. Moreover, these sources contribute to the synchrony between the release and absorption curve (Yang, 2012). However, one limitation is the high cost of their production due to the type of materials that are required to coat the granules.…”

“…These fertilizers are divided into three main groups, according to the covering agent: 1) sulfur; 2) sulfur added to polymers; and 3) polymeric and polyolefin matrices (Trenkel, 2010). The controlled release of nutrients from N fertilizers by these coating agents is considered a promising technology for improving the efficiency of N fertilization (Yang, 2012).…”

“…The use of these innovative N sources has been restricted to certain crops, especially in developing countries, because efforts were devoted to mastering the technology (Shoji, 2005;Zhouw;Shaviv, 2006;Du et al, 2008;Yang, 2012). However, with a Chinese contribution and the installation of fertilizer plants in various countries, the slow-release nutrient sources have become available for the agricultural production, especially those coated with sulfur, sulfur and polymers or polymers alone (Sanders;Mazo;Mazo, 2008;Lupwayi et al, 2010;Ogle;Sims, 2012).…”

“…The high cost of coating the granules has been the limiting factor in extending their use to large-scale agriculture (Trenkel, 2010;Yang, 2012).…”