In common nutrient management in peach orchards in China, a large amount of nitrogen fertilizer is used. However, low nitrogen absorption and utilization rate results in nitrogen loss and greenhouse gas emissions, which is not favorable for cleaner production in peach orchards. In this experiment, nitrogen leaching, ammonia volatilization, greenhouse gas emissions under bag-controlled release fertilizer (BCRF) were evaluated. In addition, the impact of BCRF on soil nutrient status in peach orchards, peach root system growth, nitrogen absorption and utilization rate, fruit quality, and the potential for using BCRF in major peach-producing areas in China to reduce the amount of nitrogen fertilizer application were also investigated. Results showed that BCRF maintained a stable supply of nutrients to soil, decreased nitrogen leaching, ammonia volatilization and greenhouse gas emissions while nitrogen loss was significantly reduced from peach orchard soil. Also, BCRF reduced the combined global warming potential at 20-, 100-, and 500-years. A 5-year study revealed that application of BCRF promoted the formation of a dense root system in peach trees by the development of fine roots and a more concentrated root distribution. This extended the lifespan of the root system and improved fruit quality. 15N tracer experiments showed that BCRF significantly increased the absorption and utilization rate of nitrogen by peach trees. BCRF reduced the amount of nitrogen fertilizers applied by 65e82% compared to common fertilizer application methods without decreasing peach yield, so it has huge potential for reducing the amount of nitrogen fertilizer used as well as fertilizer input costs in peach production. The results showed that BCRF has huge application potential as a new, environmentally friendly, low-cost, and efficient fertilizer for cleaner production in peach orchards.
The amount of nitrogen fertilizer consumed in China accounts for 30% of total global consumption. However, the utilization rate of nitrogen fertilizer is only 30e40% (Zhu, 2000). Globally, it is estimated that the amount of nitrogen fertilizer consumed will increase to 13 ۱۰۹ e15 ۱۰۹ t/y in 2050 (Matson et al., 1998). Low fertilizer utilization rate is a common problem when chemical fertilizers were used. Among chemical fertilizers, nitrogen loss is particularly serious. Nitrogen use efficiency (NUE) has decreased during the past two decades, with much of this excess nitrogen fertilizer being lost to the environment (MOA, 2007; National Bureau of Statistics of China, 2013). This not only results in direct economic losses but also environmental pollution in some cases when fertilizer application is improperly applied. This causes surface water eutrophication, nitrate nitrogen levels in groundwater exceeding standards, and increased N2O emissions (Zhu, 2000). Direct application of urea into soil will result in rapid hydrolysis and a large loss of nitrogen due to surface runoff, leaching, and volatilization and low absorption and utilization rate of nitrogen fertilizers, resulting in serious environmental pollution problems (Salvagiotti et al., 2008; Pereira et al., 2017; Wang et al., 2004). In addition, the emission of greenhouse gases, e.g. N2O, is also an important cause of nitrogen loss following fertilizer application (Pereira et al., 2015), which is not favorable for clean production in peach orchards.