The concept of controlled-release nitrogen fertilizers( CRN) as a nitrogenmanagement tool is not new.
用控释氮肥（rn）为氮素管理的一项措施已不是新概念。
2
Under the field experiment conditions, effects of site-specific nitrogenmanagement(SSNM)on grain yield and grain quality of rice were studied.
在大田试验条件下，观察了实地氮肥管理对水稻产量和稻米品质的影响。
3
The effect of different rainfall years and different water and nitrogenmanagement ways on winter wheat and summer maize was studied in northern part of north China Plain.