Use efficiency and fate of applied nitrogen in long-term tomato districts of Taiyuan

n order to manage N efficiently in long-term vegetable production districts, field trials were conducted to determine nitrogen use efficiency (NUE) and the fate of N under 2 nitrogen fertilizer application rates farmer application rate (FAR) and recommended application rate (RAR) of ¹⁵N during tomato cultivation. The results indicate that RAR does not significantly influence dry-matter of different parts, yield and nitrogen content of tomato, compared with FAR. Contrary to FAR, RAR results in lower percent of plant nitrogen derived from fertilizer (NDF). The 2 treatments yield similar NUE, which is 8%~9%. This may be due to either relative large nitrogen pool in soils, high manure application or both. 65% of the nitrogen supplied as inorganic fertilizer is lost under two treatments, and 30% under FAR and 26% under RAR of which leaches to depths over 40 cm of soil profile. It is therefore necessary to understand whether leached nitrogen is utilizable by deep-rooted crops.