1. J. Alkämper, 1976 .Influence of weed infestation on effect of fertilizer dressings. Pflanzen.Nachr., Bayer, 29 :191 –235 .
2. M. E. Cerrato, and A. M. Blackmer .1991 .Relationships between leaf nitrogen concentrations and the nitrogen status of corn., J. Prod. Agric, 4 :525 –531 .
3. C. M. Craft, and E. B. Nelson .1996 .Microbial properties of composts that suppress damping-off and root rot of creeping bentgrass caused by Pythium graminicola., Appl. Environ. Microbiol, 62 :1550 –1557 .
4. J. M. DiTomaso, 1995 .Approaches for improving crop competitiveness through manipulation of fertilization strategies., Weed Sci, 43 :491 –497 .
5. Soil Microbial Populations and Activities under Conventional and Organic Management