6Jenkison D S.Anintroduction to the global nitrogen cycle. Soil Use and Management . 1990
7Carballo S J,Blankenship S M,Sanders D C.Drip fertigationwith the nigentron and potassiumand post harvest susceptibili-ty to bacterial soft rot of bell peppers. Journal of Plant Nu-trition . 1994
8Hardter R.Plant nutrition and fertilization of vegetables for yield and quality. Agro Chemicals Newsin Brief . 1997
9Fink M.Yield and external quality of kohlrabi as affected by soil mineral nitrogen residue at harvest. Journal of Horticultural Science . 2001