ABSTRACT
A r e v i e w o f t h e l i t e r a t u r e w i t h regard t o n i t r o g e n (N) dynamics i n t h e c o n s e r v a t i o n t i l l a g e system r e v e a l s t h a t some processes have been s t u d i e d f a i r l y e x t e n s i v e l y and o t h e r s v e r y l i t t l e . Our approach i n t h i s paper w i l l be t o u t i l i z e what i s known about t h e f a t e o f N i n some processes t o e s t i m a t e t h e q u a n t i t i e s o f N which may be i n v o l v e d i n o t h e r s s t u d i e d less. Crop u t i l i z a t i o n e f f i c i e n c i e s , d e n i t r i f i c a t i o n , i m m o b i l i z a t i o n and losses by r u n o f f a r e examples o f processes on which t h e r e i s s u f f i c i e n t i n f o r m a t i o n t o reach r e l i a b l e conc lus ions about t h e e f f e c t s o f c o n s e r v a t i o n t i l l a g e on n i t rogen . The q u a n t i t y o f N t h a t i s leached o r v o l a t i l i z e d i n a conserva t ion t i l l a g e system i s l e s s w e l l known. Wi th a few n o t a b l e except ions, most researchers have ob ta ined these l a t t e r va lues by d i f f e r e n c e and we w i l l a lso.
