TY - JOUR AU - Hartz, Timothy K. AU - Smith, Richard AU - Schulbach, Kurt F. AU - LeStrange, Michelle TI - On-farm nitrogen tests improve fertilizer efficiency, protect groundwater JF - California Agriculture JO - Calif Agr Y1 - 1994/07/01 VL - 48 IS - 4 SP - 29 EP - 32 PB - University of California Agriculture and Nature Resources SN - 0008-0845 UR - http://dx.doi.org/10.3733/ca.v048n04p29 L3 - 10.3733/ca.v048n04p29 AB - Nitrogen fertility of high-value vegetable crops must be carefuiiy managed to prevent contamination of groundwater while meeting agronomic goals. New on-farm techniques of monitoring nitrogen are simple, quick and fairiy reiiable. Routine field monitoring in conjunction with periodic testing by conventional laboratory anaiysis can save time and money.