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An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3--N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg·hm-2) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg·hm-2), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg·hm-2 of urea N. The combined application of 2:1 controlled-release fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3--N leaching. At harvest, the NO3--N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment. [ABSTRACT FROM AUTHOR]

A field experiment with five treatments, control (CK, no fertilizer), conventional fertilization (U), double-effect inhibitor synergistic urea (DU), coated urea (CU) and slow/controlled release urea mixture (CDU), was conducted to investigate the effects of conventional fertilization (240 kg N·hm -2 ) and one-off application of different slow/controlled release fertilizers (180 kg N·hm -2 ) on the yield and quality of fresh maize, soil inorganic nitrogen (N), and ammonia (NH 3 ) emissions. The results showed that the total amount of ammonia volatilization was the highest in treatment of conventional fertilization (U), with N topdressing being an important source of NH 3 emission. Compared with U treatment, the NH 3 volatilization in the DU, CU, and CDU treatments was reduced by 78%-81%. At harvest stage, the soil layer of 80-100 cm in the U treatment had the highest nitrate concentration (51.6 mg·kg -1 ), resulting in a high risk of N leaching. In contrast, the nitrate concentrations in the same soil layer in the slow/controlled release fertilizer treatments were much lower, reducing the risk of leaching. In comparison with U, three slow/controlled release fertilizer treatments with 25% lower N application did not decrease yield but increased seed Vc, soluble sugar and protein contents. The agronomic efficiency and economic benefit of DU treatment were the highest among three slow/controlled release fertilizers treatments. In conclusion, the application of new type of slow/controlled release fertilizer could improve the yield and quality of fresh maize, and significantly reduce the risk of ammonia loss and N leaching. Considering the higher cost of the polymer coated urea, the double-effect inhibitor urea has lower cost and is more convenient to make. It is therefore a better choice to fresh maize planting.

An open field experiment was conducted to study the effects of applying controlled-release fertilizer blended with rapidly available chemical N fertilizer on Chinese cabbage yield and quality as well as nitrogen losses, including ammonia volatilization and NO3- -N accumulation and leaching in Beijing suburb. The results showed that a combined application of 2:1 controlled-release fertilizer and urea fertilizer (total N rate 150 kg x hm(-2)) did not induce the reduction of Chinese cabbage yield, and decreased the leaf nitrate and organic acid contents significantly, compared with conventional urea N application (300 kg x hm(-2)), and had no significant difference in the cabbage yield and leaf nitrate content, compared with applying 150 kg x hm(-2) of urea N. The combined application of 2:1 controlled-release fertilizer and urea fertilizer improved the N use efficiency of Chinese cabbage, and reduced the ammonia volatilization and NO3- -N leaching. At harvest, the NO3- -N concentrations in 20-40, 60-80 and 80-100 cm soil layers were significantly lower in the combined application treatment than in urea N treatment.